THE BOTANICAL GAZETTE THE BOTANICAL GAZETTE EDITOR JOHN MERLE COULTER VOLUME LII JULY- DECEMBER, ro11 al WITH TEN PLATES AND ONE HUNDRED AND THIRTY FIGURES THE UNIVERSITY OF CHICAGO PRESS CHICAGO, ILLINOIS TABLE OF CONTENTS The vegetation of Cranberry Island (Ohio) and its relations to the substratum, temperature, and evaporation. I (with seven figures) - - Alfred Dachnowski A morphological study of Diospyros virginiana. Contributions from the Hull Botanical Labora- tory 145 (with platesI-III) -_ - - Stella M. Hague Undescribed plants from Guatemala and ‘ie Central American Republics. XXXIV - John Donnell Smith Apparatus for the study of — trans- piration (with five figures) - Edgar N. Transeau The adult cycad trunk. Contributions ‘esa the Hull Botanical Lebo sf bb twenty figures) - - Charles J. Chamberlain A botanical survey of the ‘Hatch ‘aires Valley. VIII. Edaphic conditions in peat bogs of southern Michigan (with eight figures) - George Plumer Burns The vegetation of Cranberry Island (Ohio) and © its relations to the substratum, temperature, and evaporation. II (with one figure) - Alfred Dachnowski A preliminary report on the yearly origin an dissemination of Puccinia graminis (with plate IV) - Frederick J. Pritchard Evaporation and dai succession. Contetnatons from the Hull Botanical camemeas +47 (with six figures) - George Damon Fuller The seeraniiteate. embryo sac of Clintonia ve plate V)- R. Wilson Smith The embryo sac a Pysostgi (with plate VI and VII) - Lester W. Sharp The Brazil nut (with clits VII ed one iguse} - W.J. Young An attempted a of er ape six figures) D. T. MacDougal Contribution Bee the poke Vow Sis. ew plants from Idaho - - Aven Nelson The ie viloinent of the ascocarp of Lachnea scutellata (with plate IX and fifty-one figures) - - - - - - - William H. Brown ve PAGE vi CONTENTS [VOLUME LII Physiological behavior of enzymes and carbo- hydrate transformations in after-ripening of the potato tuber. Contributions from the Hull Botanical Laboratory 148 - - ~~ - Charles O. Appleman Reversible sex-mutants in — dioica (with fifteen figures) - - - - George Harrison Shull Reduction by layering among conifers. Con- tributions from the Hull Botanical Labora- tory 149 (with one figure) - - - - William S. Cooper The endosperm of angiosperms. Contributions from the Hull Botanical Laboratory aed - John M. Coulter Some problems in cecidology- - - - Mel T. Cook An electrical constant temperature ane. Contributions from the Hull Botanical Labora- tory 151 (with four figures) - - W. J. G. Land Light at and sac aurea ‘(with one figu Burton Edward Livingston The ik sac of Epipocis (with ole X) William H. Brown and Lester W. Sharp The oxygen minimum and the germination o Xanthium seeds. Contributions from . Hull Botanical aig seine — icici on figure) - - Charles Albert Shull BRIEFER kigtee f Edward Palmer (with portrait) - W. E. Safford Dehydrating with alcohol (with ae heures) W. A. Wullschleger Is Ophioglossum palmatum anomalous? - - M. A. Chrysler Cryptomeria japonica (with four figures) - Ansel F. Hemenway An imbedding medium for brittle or — tissues - H. M. Benedict Apogamy in Pdllaes ouuehus W. N. Steil A ease oan of ipo (with one gure - W. J. G. Land CURRENT trees - - - - - 6, 155, 233, 316, 402, For titles of book reviews see index under author’s name and reviews Papers noticed in “Notes for Students” are indexed under author’s name and subjects. DATES OF PUBLICATION No. 1, July 17; No. 2, August 18; No. 3, September 15; No. 4, October - 17; No. 5, November 15; No. 6, December 19. PAGE 61 63 151 153 232 400 478 480 Os ro be ERRATA 24, line 3 from bottom, omit Cornus canadensis. 24, line 1 from bottom, for Prunus read Pyrus. 26, line 7 from bottom, omit Alnus incana. 27, line 7 from top, for ovata read canadensis. 210, line 18 from top, for spongioplasm read cytoplasm. 237, footnote 1, for Ernest read Ernst. 264, line 18 from top, for Roripa terristris read Roripa terrestris. 273, line 5 from bottom, for anthers dehiscent read anthers dehiscent to but not through the apex. 330, line 26, for formula read formulae. . 395, fig. 3 legend, for gasket read socket. . Lil Vol * Mares te at Mae a The University of Chicago ” Offers instruction during the Summer Quarter on the same basis as during the other quarters of the academic year. The undergraduate colleges, the graduate schools, aid the pro- fessional schools provide courses in Arts, Literature, Science, Law, edicine, Education, and Divinity. Instruction is given by — the summer by we Sa a of professors and inst other institutions. Be ae =| < Detail announcements. are now ready fai _ be sent dice a ples : Lee M regular members of the University staff, which is suppontes 3 in- - Fs The Botanical Gazette A Montbly Journal Embracing all Departments of Botanical Science Edited by JOHN M. COULTER, with eet hae ie of a members of the botanical staff of the ersity of Chi Issued July 17, 1911 Vol. LII CONTENTS FOR JULY 1913 No. J THE VEGETATION OF CRANBERRY ISLAND (OHIO) AND ITS RELATIONS TO THE SUBSTRATUM,, ene URE, phe EVAPORATI pts I Vereen: 9 SEVEN PPECURES). Alfred Dachnow shi - - A MORPHOLOGICAL STUDY OF DIOSPYROS VIRGINIANA. ee. FROM ‘ 4 HULL BOTANICAL LABORATORY 145 (WITH PLATES I-11). Stella M. Hagu 34 «sgeaae dala PLANTS FROM GUATEMALA AND eerie ces abi ince bs Se LICS. XXXIV. John Donnell Smith - 45 APPARATUS FOR THE eed OF EAA TS sc vesic dela cnet (WITH FIVE £ FIGURES). Edgar N. Transe - - - 54 aaj ee ES RD PALMER (WITH PORTRAIT). W. E. Safford - - . - . - on ar oe WITH ALCOHOL (WITH FOUR FIGURES). W. A. Wullschleger - . tee SS CURRENT LITERATURE MINOR NOTICES - - 5 - . “ - - : A , eu Oe OTES FOR STUDENTS ee ay ei et re 8 The Botanical —- is published monthly. ‘rhe subscription price is $7.00 per year; the price of single copies is 75 cents, [Postage is prepaid by the saan on all orders from the United States, _ Mexico, Cuba, Porto Rico, Panama Canal Zone, Republic of Pan pI es Philippine — Guam, Tutuila (Samoa), Shanghai. Posta i is charged sy as follow r Ca annual nani pal Sapa $7. 35), on single copies, 3 cca (total 78 apes for all other Santee in the Postal Union, 84 cents on ann subscriptions (total $7.84), on single copies, 11 cents (total 86 cents). A esmiltances Seaaid ts e made a to The University of Chica ago Press, cad should be i in Chicago or _ New York exchange, postal or express money order. If local check is used, 10 cents must be added _ for collection owing agents have been appointed and are age oa 2» quote the ea indicated: For the British Empire: Cambridge a Press, Fetter Lane, London, E.C., and William esley & Son, 28 Essex Street, Strand, rierar Yearly abvacsiplions, heleding seater: £1 12s. 6d. Hara bag ne Sonne ge ita. 3s. rage 4 e Cont of Europe: Th. St silles: Dnsvecsiitiaeteause ci ree. hese i Yearly sub- Serigtion. piroraie postage, M. a each; single copies, cecnpapd postage, For Japan and Korea: The Maruzen-Kabushiki-Kaisha, o 16 Niho ak a Toe Rasalan Tokyo, Japan. Yearly s ubscriptions, including postage, Yen I rene rata single copies, including postage, ach. : i issing numbers should be made within the month following the regular month of publi- _ cation,’ 7 publishers expect to supply a: numbers free only when they have been lost in transit. correspondence should be addressed to The University of Chicago Press, Chicago, Ill. Communications for the editor should be eet to him at the University of Chicago, Chicago, Ill. Contributors are requested to write scientific and proper names with particular care, to use the metric system of — and measures, and i in citations to follow the form shown in the pages of the BOTANICAL ETTE. Pa apers i excess of thirty-two printed pages are not viper pi the author is sive Sh to it the cost of the additional pages, in which case the number of pag . ustrations orga without cost to i aes oie suitable originals are e supp lied: ee copy of the i ceeaeitioks® ate the January number, 1907, will be sent on application. It is advisable to confer with the editors as hae illustrations required in any article to be offre ost s printed on an order blank which | Sp esuspanies the e proof; a copy will be sent onr Entered August 21, 1896, at the Post-Office at Chicago, as second-class matter, under Act of eet March 3 1879. * a ITALIAN BOOKS ery description ITALIAN ‘BOOK ae PANY FRANCESCO. TOCCI orks of: Barrili, Butti, Caccianiga, Capra- nica, Capuana, Carducci, Castelnuovo, Cor- delia, D’Annunzio, oe Am is, woe rchi, arina, zaro Negri, Praga, pater Serao, ree oe ating writers, always on hand ; Cabiiane mailed on application. BRANCH 147 MULBERY The Botanical Gazette Edited John M, Coulte Publish Pragacgren with illustrations. Subscription price, ies, 75 cents; foreign postage, & THE UNIVERSITY OF GHICAGO PRESS ————————GHIGAGO, ILLINOIS ted by Thomas C, ee: Sere 9 J | - cancaniceety, with illustratio a Subscrip- rma ion price, 3.00 a pe bh shea le copies, ou cents; foreign postage, 53 ; rg i . THE UNIVERSITY OF cencao PRESS CHICAGO. ILLINOIS Contributions to Medical Science By Howard Taylor Ricketts tees as a Tribute to His Pesto: by His lleagues under the Auspices of the Chie icago Pathological iSpoter R. RICKETTS died of typhus fever i pe the e Mountain spotted fever, give Dr. Ricketts a high and honorable place on the records of medical rese. The present volume contains thirty papers on these and allied topics. It is rich in informa- memorial to a man whose life was s detineeatell laid down in the service of humanity. 508 pp., 8vo cloth; net $5.00, domestic postage 33¢- The en of Chicago Eatice: Chica A Laboratory Guide in Bacteriology By PAUL G. HEINEMANN Second Edition, Enlarged and Revised The Guide is confidently offered in the than did the first edition, to elementary students in medical bacteriology, the bacteriol water and milk, soil a and in ” dents of domestic science and for those who in the various branches of bacteriology. 216 PAGES, 12MO, CLOTH FUSIFAID + “= «< S159 The University of Chicago Press Chicago, Illinois SECOND EDITION, ILLUSTRATED on INDISPENSABLE BOOK R STUDENTS OF BOTANY Methods in Plant Histology By CHARLES J. CHAMBERLAIN, Pu.D. of the Department of i in the Univers ee of Ch HIS BOOK contains directions for collecting and prepare plant material for mi resceret investigation. It 7 upon a course i tanical micro-technique and is Tr aise t ¢ manual to be published on this subject. at te requirements, not only o tudent io assistance of an instructor in a fully equippe “4 limited also of the student who must work by himself and wit il ap Freehand sectioning, the para d a in methoc glyceri ethod are treated in consi tind detail. In later chapters specific directions are given == ee such preparations as are needed by those who wish to stuey =~ t tab —_ hog ray ni he = ay ore plants. sgh et Sabooes tg i a new edition includes a description of Klebs’s met na ce hae suring es ctive phases tn, the a'gae and fungi, ao te ers on the Venetian “ tine method, sicrochemica free-hand sections, special methods, and t of the micro. scope. The volume is thus enlarged from 1 272 pages- $2.25 netz $2.39 car THE UNIVERSITY OF CHICAGO PRESS CHICAGO. IT LINOTS CHE BoA SICAL. CGAZETTE JULY ort THE VEGETATION OF CRANBERRY ISLAND (OHIO) AND ITS RELATIONS TO THE SUBSTRATUM,-TEMPERA- TURE, AND EVAPORATION." I ALFRED DACHNOWSKI (WITH SEVEN FIGURES) The object of the present paper is to give, as briefly as is con- sistent with a limited presentation, the major conditions of some of the factors which have been found limiting the activity of plants in bogs. The striking discontinuity of bogs in distribution, the absence of genetic relationship between bog plants and the surrounding flora of states in the latitude of Ohio, and the floristic agreement of these plants with the vegetation of the distant north has invited the attention of many students of ecology. As early as 1872 a solution of this interesting problem had been formulated by Gray (14) in his glacial relict theory. A similar explanation has been advanced by numerous recent writers, and the broader relations which involve comparative studies have been well established (31). However, the reciprocal relations of these plants and their habitat, the demands which the plants make on their environment, the means which they employ, and the functional réle which the particular species perform; in short, an investigation of factors by which the present associations are determined and which would account for the existence and the peculiarities, structural and functional, of these ‘‘boreal” plants * Contribution from the Botanical Laboratory, Ohio State University, no. 61. I 2 BOTANICAL GAZETTE [JULY on the basis of their relation to the present ecological conditions of their habitat, this has been a far more difficult matter and has not met with unanimity of opinion. A knowledge of the flora of a region and the floristic status of successive periods of time is indispensable, if for no other reason than to indicate the various conditions frequented by species or groups of plants. But the statistical method must be supplemented by an adequate study of experimental tests. The varying activity of plants as individ- uals and communities is of greatest importance scientifically and must be determined in the field under measured conditions. Various theories have been put forward from time to time as to the environmental relations of plants in bogs, but none of them can be said to have brought nearer a solution of this phase of the problem. The historical aspect of the question need not be dealt with here in detail. The more important theories are those advanced by the following writers: Kra~MaNn (19) regards low temperature and strong drying winds as the prominent factors in high northern latitudes; ScarmpeR (29) emphasizes humus acids in the soil, abundance of soluble salts and alkalies, and regards bog habitats as being ‘‘physiologically dry’’; LivinGsTON (22) suggests the presence of chemical substances not in direct relation to acidity of the soil as acting on the vegetation; WARM- ING (32) is inclined to look upon the presence of free humus acids as the weightiest cause; Frita and ScHRrOTER (13) correlate the conditions with low temperature and lack of aeration in the soil; while SCHWENDENER (30) and CLEMENTS (5) hold that the structural peculiarities are not at all related to present habitat conditions but are primitive peculiarities, which now remain unal- tered but were originally developed under different xerophytic conditions. Another explanation, that of the toxicity of the habitat, and its consequent physiological aridity and selective operation upon forms striving for occupancy, has been offered by the writer of this paper. This view has come from a more detailed investigation of the physical and chemical characteristics of bog soils and their physiological property (7, 8). It emphasizes the active participation of specific microorganisms and fungi, a view which correlates also very well with the unproductiveness of differ- 1911] DACHNOWSKI—CRANBERRY ISLAND 3 ent peat soils under cultivation examined by the writer, and lays stress not alone upon structural characteristics in plants but also upon limiting habitat conditions as conducive to the development of place-functions. That various factors enter into the problem, and possibly many others not yet discovered have a part directly or indirectly, is clearly recognized. Further field work on the bog plant societies has been carried out especially with a view to test the reference made by several writers to the part played by low substratum temperature and by the evaporating power of the air. In addition, studies on the physical, chemical, and biological problems of the substratum were continued. It is obvious that the physical conditions, whether temperature or evaporation, if sufficiently great in their differences, must have an important bearing on the question of distribution and of xero- phytism in bog plants. The larger part of the body of bog plants is imbedded in the peat at various depths. The various functions take place only within lower and upper critical conditioning fac- tors. For instance, the germination of seeds, the activity of roots and rhizomes, the permeability of protoplasmic membranes, the rate of absorption and chemical action during growth in under- ground organs, must be greatly affected by the actual extreme temperatures encountered, as well as by the rapidity with which changes in temperature occur. The diurnal and seasonal temper- ature changes in the peat soil, and the differences in temperature between the aerial and underground portions of plants cannot fail to be of equally great importance in the physical and chemical Processes, in the activity of the soil organisms on those biological changes which modify soil productiveness, and in the reciprocal Physiological influences upon which absorption, transpiration, and transport of solutions from one part of the plant to another depend. The task of securing.a coordination between these functions must be indeed a complicated one, varying greatly in different species according to their capacity of endurance. It is therefore clear that conditions as regards efficient temperature determine greatly the phy siognomy of the individual plant and of the whole of the vegetation in habit of growth and distribution. But the rdle 4 BOTANICAL GAZETTE [JULY which temperature plays quantitatively and qualitatively in the distribution of bog plant societies is in the main not known. So far as the writer is aware, no quantitative measurements between temperature as a probable causative or limiting factor and the resulting function and form in bog plants has been previously conducted, such as would afford any definite record of the actual physical conditions obtaining at different substratum levels in a bog vegetation. What has been said for temperature holds true also for evaporation. The influence of this and other factors is among the pressing problems of physiological ecology. From this point of view the data presented below have been collected in the field during the past three years. The physical factors which modify and more or less control the community of plants on Cranberry Island have been formu- lated for the most part quantitatively. Yet it must be frankly admitted that, at the present time, interpretation of the data thus far gained is still only in-part possible. Though the data have been gained laboriously through many months, and to the writer seem convincing, to attempt to correlate these accurately may be ill-advised. Only by the multiplication of such data will it be possible to express the results with quantitative exactness. The very necessity, however, of recording and accumulating an extended series of comparative observations is the justification of publishing now the data at hand. The conclusions here expressed, therefore, are still tentative, and true for the local investigation only. Frequently the writer’s students have assisted in this work, and acknowledgment is due to Messrs. L. W. SHERMAN, E. Wricat, E. Linn, L. Kine, and M. G. Dickey for efficient aid. The warmest thanks of the writer are expressed here also to Professor J. R. CHAMBERLAIN, who surveyed the island, to Pro- fessors N. W. Lorp, W. E. HENDERSON, and C. W. Foutk for cooperation in the chemical analyses, and to Miss F. DETMERS for identification of plants and the care with which the floristic — study has been generally furthered. The expense of the field work has been covered in large part by a special grant from the Emerson McMillin Research fund. 1911] DACHNOWSKI—CRANBERRY ISLAND 5 The habitat The field work which forms the basis of the present paper was carried on at Buckeye Lake, Ohio. The geological record of the region is for interest second to few places in Ohio. The strata furnish an almost unbroken narrative from the Silurian up to the Tertiary. It is a rare thing to find peat bogs in Ohio south of latitude 40°, and this circumstance makes the locality as the southernmost limit of existing peat formations still more interest- rae 7 net = oe ue a #9? we if fe a= TICKING CO) Ot pe j ; i “FAIRFIELD CO, en ES} 4 av | (aur LADD Fic. 1.—Topographic map of Buckeye Lake and vicinity; U.S. Geological Survey, 1907; Contour interval 20 feet (6 m.); scale, 1 inch=1 mile (2.5 cm.=1.6 km.). Fae t VU G eed NSC S29 89 be Tel Broan); ing. And to complete the panorama of the great past, the remains of the moundbuilders found near Newark, Jacksonville, and other Places in the vicinity continue the record down to the historical period. Buckeye Lake is situated in Licking, Fairfield, and Perry counties, about 26 miles (41 km.) east of Columbus, and is at an - elevation of 1 50 feet (45 m.) above that of the University campus. The area and location are shown on the Thornville sheet of the US. Geological Survey (fig. 1). The lake, like many others, is one characteristic of the highlands of watersheds throughout Ohio and adjoining states. The heath bogs in Wyandot County, the extensive bogs in Huron County, possibly among the largest 6 BOTANICAL GAZETTE ; [yuty peat deposits in the United States, the Pymatuning tamarack swamp in Ashtabula County are similar members of this inter- esting chain of water basins marking the less perfectly drained sum- mit of divides. The depressions on such summits receive water which creates no surplus and hence has almost no eroding powers. Buckeye Lake is now an extensive body of water, about 10 miles (16 km.) long, and one mile (1.6 km.) wide, but was originally a pond in the glacial drift, containing approximately 595 acres (238 hectars). Its chief water supply today is the south branch of the Licking River. The lake basin lies near the binthioustenn margin of the terminal moraine. The main western member of the morainic system is about 3-5 miles (5-8 km.) in width. It presents marked differ- ences in topography, the closely aggregated knolls and ridges rendering the belt readily distinguishable from the bordering plain. The knolls are generally conical in form with gentle slopes, ordi- narily about 25-100 feet (7.5-30 m.) in height. These knolls were apparently formed at the time the gravel plain was being built up. They are thought to indicate that the head of the gravel plain was built up as a submarginal deposit to about its present height before the ice sheet had withdrawn from over it (20). The lake basin under discussion resulted from the comparatively slow retreat of glaciers and the consequent greater deposition of gla- cial material about the edge of a body of ice in an old glacial drain- age channel. The “kettle” is characterized by comparatively steep slopes. Up to 1832 the lake was surrounded by about 3000 acres (1200 hectars) of swamp land covered with large trees (fig. 2). The report of Captain CHITTENDEN, as quoted by Gray (15), gives the area of the lake at that time as 3300 acres (1320 hectars), which agrees very closely with its area as deter- mined by later surveys. The present lake was formed in 1828 and completed in 1832, to serve as a reservoir for the Ohio and Erie Canal. The surface water was raised about 8 feet (2.4 m.) by forming a dike around the west end and a part of the north side of the swamp. It was hoped to supply the Ohio Canal with water from Newark to Little Walnut Creek, south of Lockville, a distance of 31 miles (5 km.), and the deficiency between Little DACHNOWSKI—CRANBERRY ISLAND tort] ‘OIyO ‘snquinjor 7e asoqJO s,1oyIpNy 971g 94) Ur sdeur AdAans dy} Jo sButovsy wosy {6061 puv 6641 ul aye] aAayongG—‘z ‘ory ‘6067 40 Agrsng ~---~— 66L/ 40° haaing SU/IDYD O% =,,/ 2/029 Wy 5 / us ~ Stra 8 BOTANICAL GAZETTE (JULY Walnut Creek and Lockbourne. The reservoir soon proved inade- quate for the canal, and in 1834 about 700 acres (280 hectars) were added, forming its present area. Its watershed embraces about go square miles (2331 hectars), which cannot be greatly enlarged. The lake then known as Licking Reservoir has, however, never stored a sufficient water supply and is not used for transpor- tation purposes now. A large number of trees then standing soon died and fell into the water, where they remained beneath the surface. The majority of the trees were gradually cut away with Fic. 3.—Cranberry Island; the view is from a hill northwest of the island near Buckeye Lake Station; to the left the woodlot; in the distance members of the ter- minal moraine; photographed August roto. their stumps exposed during low water. Only recently (the winter of 1908) the greater part of these stumps has been removed. Near the northern bank of the lake, about one-half mile (0.16 km.) southeast of Buckeye Lake station, is the bog island, approxi- mately one-tenth the dimensions of the lake (fig. 3). In position it is more or less sheltered by hills and a woodlot. The peat mass rises and falls with the changing water level of the lake, and supports a vigorous growth of trees, low bushes, sphagnum mosses, and cranberrries. Borings were made at various points on the island with a sampling tool devised by Davis (2), to determine the depth and the character of the peat. About 50 soundings were made, which indicate an average depth of peat of 30~35 feet (9-10 m.) along the southern shore of the bog island, and 11 feet 1911] DACHNOWSKI—CRANBERRY ISLAND — 9 (3 m.) of peat along its northern shore. Borings made to the depth of 40 feet (12 m.) at the southernmost points of the island, and in the lake south of it, failed to reach bottom. The following table (I) gives some of the borings and related observations. The borings were made at a time when, for purpose of repair, the water surface of the lake was lowered 5 feet (1.5 m.) below the normal niveau. TABLE I ANALYSIS OF PEAT SPECIMENS FROM CRANBERRY ISLAND, BUCKEYE LaKE, OnIo = sis Station io Description of peat samples 5.....|/Central zone; 5 1.5 | Brown, fibrous peat; mostly cranberry, sphag- sphagnum- num, and sedges cranberry 7 ene 14 4.2 | Brown, non-fibrous, plastic peat with diatoms and shell m _ eee 25 7-5 | Dark brown 1 decayed, finely granular peat; algae Oy and filling from marginal bor OQ... 40 12.0 | Nearly ‘ack: non-fibrous, clayey peat. it EL Maple-alder 6 1.8 | Dark brown, slightly fibered peat, coarser zone fibered below eae to §=6©3.0 | Brown and fibrous pd rates 18 5.4 | Dark brown, wel eae, finely granular peat with shell marl. 2 eae eae 31 9.3 | Fine sand with clay underneath. age. Northeast eee —— — ae nat cranberry, sphag- station 26 75 $54 Granular peat ; ae sandy above, marly eat. 27-+... 28 8.4 Seems marl; blue of penetie. ae Southeast ee ee rown, coarse fibrou station 29..... 1673.0 po wade: mage fibrous; a lighter colored fibrous peat —— rneath. gO. -... 20 6.0 | Bro a Brows, fe ontaining roots and rhizome fra 3I..... 40 12.0 ae ee plastic, en peat; bottom not 32.....| Southwest 5 Light faves coarse fibrous peat. station Sees 20 6.0 | Plastic, was st ee dark brown peat contain- ing shell i Ee 40 12.0 ges. plastic, non-fibrous peat; bottom not fe ene Northwest 5 ee Light | Gece: fibrous peat, = of sphag- station m and other bog plants 42..... 20 6.0 | Fine fibered, dark b peat. po ee 8 8.4 | Sandy gra ravel underlain i. blue oy Fh anes Lake station 6 1.8 | Dark brown, slightly fibrous peat AQ... 40 12.0 iam plastic, non-fibrous peat; bottom not ses d. ite) BOTANICAL GAZETTE [JULY It will be seen that the accumulation of vegetable matter has been sufficient to cause the lake basin to be filled with a layer of peat of considerable depth. The deeper strata have been reduced by humification, largely to the form of a black humus, a semi- liquid muck. The fineness of grain and the peculiarly soft con- sistency of it suggest that it is in part made up of the remains of algae, and in part a filling from the border of the lake, spread over the bottom. The upper strata are lighter in color, and very fibrous, loosely felted in structure, and have a matted appearance. As the island is sounded through from top to bottom, the samples brought up show a progressive change in color from light to darker shades, and in texture from coarse and loose to fine and more compact peat always saturated with water. In some places this sequence is repeated, that is, below the peat muck occurs a second fibrous brown layer followed by muck or clay. The escape of gases is very noticeable during the test borings, and also the stain- ing of the brass peat sampler to a bluish-purple bronze, indicating the presence of a gas like hydrogen bisulphide. Only a small de- posit of shell marl has thus far been found underlying the peat substratum in places. The Characeae and Cyanophyceae con- cerned with this process (10) are not abundant enough to be con- sidered as agents in the aggradation of the basin. The lake bottom is of clay and in places somewhat sandy. The thickness of the deposit of peat in this morainal depression indicates, therefore, that the vegetation must have obtained an early foothold. The chemical analysis of the substratum The drainage of the bog island is merely that due to seepage through the porous peat. Ordinarily very little water passes either into or out of the bog island, except at such times when the water level of the lake fluctuates with extremes in precipitation or from interference in drainage. Even then the seepage is not rapid. The amount of salts dissolved in the lake water which is retained by absorption in the humus soils along the margin of the bog island is relatively small. The analyses show a total mineral content of 4 and 9 parts per hundred for the central and marginal zones respectively. Average samples of the air-dried peat taken 1911] DACHNOWSKI—CRANBERRY ISLAND II at a depth of one foot (30 cm.) from the surface layer give the following chemical composition (table II). For purposes of com- parison analyses have been added of peat soils from a tamarack bog near Edgerton, Ohio (station VII), from a bog near Orrville, Ohio, now under cultivation in celery, onions, etc. (station VIII), and from a peat bog under cultivation, the soil of which is reported as unproductive (station IX). TABLE II CHEMICAL ANALYSES OF PEAT SAMPLES Sph - ‘ ‘ Cnstiinends cranberry Maple-olier saree — — Volatile matter......... 60.90 68.91 60.50 52.47 52.56 pee Carbon. 65. os k 22.19 19.60 26.84 23.98 19.35 BM eek ee 7.68 3.56 3-30 14.70 19.42 MR Git ae 0.12 ©.00 ©.20 0.39 2.21 Nitrogen (equivalent to J eae 0.80 2:55 ey | 2.58 2.38 Pota er hopes 0.12 0.12 0.15 0.31 0.64 Phosphoric acid (P20,).. 0.03 0.03 0.29 0.34 0.37 eebes ee 0,00 ° 0.15 0.07 0.15 AeGabL CNS os Sema ch 0.03 0,03 O.14 0.27 0.22 It appears, therefore, that where peat varies from a highly fibrous condition, light brown in color, as in the sphagnum-cran- berry zone, to a structureless condition, i.e., well decomposed, only slightly fibrous, and dark brown in color, as in the maple-alder zone, not only the physical constitution but also the chemical composition is highly variable. The determinations, which were made in the same way as fertilizer analyses, show conclusively that from the standpoint of available plant food constituents, the peat of the maple-alder zone is superior to that of the central sphagnum-cranberry zone. The analyses of peat ashes indicate only a small fraction of a per cent of potash and of phosphoric acid, but a fairly large amount of the valuable nitrogen ingredient. Preliminary work indicates also that the relative availability of the peat nitrogen seems at the most 8 to 12 per cent; but that this relative availability of peat nitrogen is considerably increased when the peat is composted with the bacterial life from stable manure, the peat from the central sphagnum-cranberry zone dis- 12 BOTANICAL GAZETTE [JULY integrating, however, less readily than that from the maple-alder zone. The reducing action of peat soil It is a well known fact that fresh samples of bog soil upon expo- sure to the air extract oxygen from the air with great rapidity. Soil-sampling tests show that this power is strong in the cranberry- sphagnum peat, reaches a maximum in areas where the peat sub- stratum is compact and less coarsely fibrous, and decreases as the border zone along the margin of the lake is reached. Judged by the quickness with which the soil becomes colored, and the inten- sity of the color, reducing processes increase on Cranberry Island from any marginal point to the central zone, and decrease as the opposite shore is approached. Reduction action becomes greater with the depth of the deposit. The reducing power of the soils is shown clearly by the addi- tion of a starch iodide solution. The observable action is variable, as already mentioned; the blue color disappears rapidly in soils from the cranberry-sphagnum area; the solution is greatly light- ened with soils nearer the margin of the lake; no action is detected with soils along the margin. Various dyes such as lacmus and methylene blue and other coal tar colors decolorize similarly. Possibly the absence of sulphur in the analysis of maple-alder peat (table IT) is due to the complete conversion of sulphur to hydro- gen sulphide. This gas is the product of a reduction and has been detected by means of lead acetate paper. Whether the reduction power in peat soils is produced by micro- organisms, is due to enzymes, or caused by external chemical or bacterial metabolic products, these tests fail to show. Nothing absolutely certain is known regarding the composition and the nature of reducing substances. They have not at present been very fully studied by ecological workers. Apart from their destruction by aeration, tillage, and heat, and their adsorption by insoluble substances such as quartz, kaolin, carborundum, lamp black, and others, uncertainty exists as to whether the redu- cing bodies in bogs are unsaturated compounds comparable in properties to unsaturated fatty acids, to substances which possess the characteristics of certain organic reducing ferments, or to rorr] DACHNOWSKI—CRANBERRY ISLAND 13 residual by-products of an incomplete disintegration of peat. They unquestionably reduce oxygen-containing compounds in contact with them; their action is most marked where micro- organisms play a part in decomposing organic matter; the amount reaches, it seems, a maximum in early autumn. It should be stated further that toxicity and the reducing action of peat soil and that of the decomposing organic matter which retards oxida- tion in the soil are not necessarily the same phenomena. An increase in the amount of oxygen does not always decrease toxicity or the reducing power of the soil, and hence the amount of oxygen absorbed cannot be taken as the measure of the total action of these conditions. Reduction processes are predominant in the early stages of peat formation, but are less manifest as the concomitant plant societies are succeeded by others, and especially when deciduous forests prevail. The same factors which decrease the toxicity of the habitat and the accompanying reducing processes favor an increase in the rate of oxidation and influence thus the character and nature of the succession. The greater oxidation, therefore, in the known productive peat soils would seem to be due to the activity of a different set of microorganisms, which by enzymotic action or otherwise hasten the formation of compounds of an assimilable nature. The excessive oxygen avidity of peat soils in the early formation stages must undoubtedly be injurious to plants, unless the plants, indigenous or invaders, are likewise able to exhibit oxidizing or reducing powers. The reducing processes in a soil very likely activate oxidative powers in plants. The various reactions of fungi, micorhiza, alder tubercules, bacteria, and the roots of higher plants growing in peat and humus soils should on that account be made the subject of considerably greater and more detailed study. The consideration of the relation between plant societies, relative physiological aridity, and micro- Organisms, with their reductive and oxidation processes in soil has scarcely passed beyond the theoretic field of speculation. And yet it is this relation which makes soil problems especially interesting and in need of experimental work of considerable scope (28). 14 BOTANICAL GAZETTE [JULY The bog water is relatively clear, the suspended particles imparting to it a slight tinge of olive green to brown. The analy- sis of samples of bog water and lake water give the following results (table III). TABLE III CHEMICAL ANALYSIS OF BOG WATER AND LAKE WATER FROM CRANBERRY ISLAND Constituents i " B cynic per = . Bog water, central zone (May 30, Igto) (cranberry-sphagnum) Lake water Nitrogen as albuminoid ammonia........ 10.34 4.50 Nitrogen as free ammonia. ...........:.. 5-19 2.95 eererogent WS TEER. cc es es 0.0005 ©.0000 Ni Se WS NIALES oe i eS 0.20 °.10 ete eee ee Oa 0.30 1.00 PeQUIEGd OLY GER. oe ee ee 71.80 3.490 Alkalinity, rob CaCO.) ee ee a 30.00 75.00 In ieiparcid ae) es 74.00 76.00 Aetab BOUCSSe e eoy ye h s 140.00 200.00 Loss on naeenhey Sore eo ek ey aay us Gee 100.00 4.00 Examining these results, shown in table III, we find that the lake water contains organic matter in a state of advanced decomposition. This is indicated by the relatively high free ammonia, and the small amount of oxygen consumed. The reverse holds true for bog water from the sphagnum-cranberry zone. In other points lake water agrees well with bog water. The osmotic pressure and the acidity have been found to be the same for both stations. As compared with the freezing point of pure distilled water, the average lowering in the various deter- minations is o°007 and o°009 for the central station and the maple-alder and lake station respectively. Acidity varies from less than 0.00075 to 0.0038 normal acid when titrated with a n/o.o5 NaOH solution. The soil is alkaline at depths near the marly subsoil. The stress laid by various authors upon the re- lation of these two factors to plant societies in bogs, in so far at least as this region is concerned, will not hold. They are not factors in the selection or distribution of species for bog habitats. Physiological properties of bog water The physical and chemical sides are found unsatisfactory to explain the functional variations and the pathological changes 1911] DACHNOWSKI—CRANBERRY ISLAND T5 in structure which agricultural plants undergo when growing in peat and bog water. Elsewhere it was shown by means of tran- spiration data of cultivated plants, and with a biometric study on the annual wood-increment in the red maple found on the island and in woodlots near the shore, that (1) a difference exists between different species in their power of resistance to the toxic action of the substratum; (2) the contrasts in the relative growth of plants vary with the substrata of the several bog plant formations; (3) the toxic principles whether enzymes or other bodies are not found in bog water when attempts are made to extract them with insoluble adsorbing bodies; they do not pass readily through fil- ters and only slightly through filter paper; (4) different physiologi- cal phases result from the progressive addition of an adsorbing substance; (5) agricultural soils used as filters decrease con- siderably the normal physiological activity of plants growing in them; (6) the reduced absorptive capacity of the plants is not a consequence of the absence of root hairs, or of a smaller absorbing surface. The bacterial flora of the peat substratum Present writers seem to hold the view that among the simplest of fungi, the Schizomycetes, few are present in peat bogs, and that only a small number of species, included in perhaps only one family, are at all injurious to higher plants. Examination has shown that peat soils contain unsuspected groups of bacteria, which in number and efficiency vary during the seasons and with the several plant zones on the island. As a means of differentia- tion between the bacterial flora of the plant formations, studies were made on the action of the bacteria in 0.5 cc. bog water upon various culture media in fermentation tubes. Soil water solutions were collected in sterilized glass-stoppered bottles from each of the following stations: station I, lake water; station II, marginal zone (Decodon-Typha-Hibiscus); station III, cranberry-sphag- num zone, 1-3 feet; station IV, same, 3-5 feet below surface vegetation; station V, maple-alder zone, 1-3 feet; station VI, same, 3-5 feet below surface vegetation; station VII, tamarack soil from Edgerton, Ohio; station VIII, peat soil under cultiva- 16 BOTANICAL GAZETTE [JULY tion from Orrville, Ohio; station IX, peat soil under cultivation, reported as unproductive and ‘“‘sterile,” from Lodi, Ohio; sta- tion X, humus soil from the university woodlot (beech-oak-maple- elm). The culture media employed for this work were a 1 per cent starch peptone water solution; 1 per cent solutions of cane sugar, dextrose, and lactose in beef broth; plain bouillon; plain and litmus milk; 0.2 per cent nitrate peptone water; Dunham’s peptone solution for the indol test; nutrient gelatin and agar. Only the generally well known determinations, as of the breaking up of carbon and nitrogen compounds and the proportion of the various gases evolved, have been made. The chemical analysis of the soil samples of stations I to IX is given in tables II and III. The culture studies gave the following characteristic results after an incubation period of 5 days at 38° C. The action of the bacteria on starch shows in several stations the production of an inverting ferment by the cultures. The starch is changed into a sugar which reacts with the Fehling’s test. In stations III and IX there is no action; in stations II and X the conversion is carried on a little way and then stops, there being always a red or purple reaction with iodine; in station I the starch conversion is almost complete; while in stations IV, V, VI, and VII certain putrid by-products inhibit in various degrees further conversion. Upon the addition of a few drops of potassium iodide, the blue color disappears rapidly in stations III, IV, and VI; the hydrated iodine is deposited as metallic iodine upon the walls of the test tube above the solution. Reduction action is less active in sta- tions V, VII, and IX. No decolorization occurs in stations I, II, and X. The accumulation of iodine is very strong in the test tube of station X and is very likely an indication of the presence of oxidizing ferments. With methylene blue the reduction action is the same in degree, respectively, in all cases running parallel with the iodine action. In all stations, with the exception of station I, the action of the bacteria on saccharose shows both the conversion of the carbo- hydrate into glucose by the inverting ferment, and the production of gas and acid. The reaction is strongest in stations VIII and X; relatively small in stations V and IX; very little gas is evolved 1gtt] DACHNOWSKI—CRANBERRY ISLAND 17 in station II. The gas is largely hydrogen gas and CO,; the latter, with the exception of stations V and VIII, is present usually in small quantities and was distinguished from other gases by its absorption in sodium hydroxide. Fermentation action is shown better on dextrose and lactose. There is little growth and gas formation in station I; no acid is produced in stations VII and IX; and very little hydrogen gas is formed in station VIII. In all cases the growth of the organisms produces a marked and varied pigmentation in the solutions. In plain milk, rapid coagulation precedes further bacterial action in all cases except station IX, in which coagulation occurs very slowly. Milk is slowly peptonized anaerobically in stations IV, V, and VI; surface digestion takes place in stations III, VIII, IX, and X; it is rapid in stations I, III, and VI; and gas is pro- duced in moderate quantities in all stations except station VIII. Litmus milk is coagulated in all stations; the medium gradually decolorizes and the cultures become acid in various degrees; the color does not return upon steaming the test tubes. With a majority, gas is produced in various amounts during digestion, except in station [X, in which the bacterial reaction is faint though strongly odorous. On bouillon bacterial growth is slow; it is never very turbid or heavily clouded, and only in one case, station IX, gives a whitish precipitate. The power of indol production is greatest with the organisms in stations III, V, and IX; the action is relatively small in stations II, IV, VI, and VII; and present to a feeble extent only in stations I, VIII, and X when tested with 0.02 per cent solution of potas- sium nitrite and sulphuric acid. The ability to form nitrites from nitrates in nitrate broth is common to the organisms in all stations. The amount of nitrites formed is high in stations IV, VI, IX, and X, and very small in stations I, 7, VII, and VIII. The power to reduce nitrates to nitrites is not present in the same degree as noted above for the reduction action in starch media. It is certain that the micro- organisms are capable of reducing nitrates, but to some extent metabolic products, apparently, modify the action. The test 18 BOTANICAL GAZETTE [JULY was made with equal parts of sulphanilic acid and napthylamine solution. The presence of ammonia was tested with Nessler’s reagent. The reaction is stronger in stations VII and X than in any other station. A faint test is obtained in station IX. Nitrogen gas is produced from nitrates in stations VII and VIII.” Before summarizing the facts brought out in the culture studies, there is need of mentioning another matter. A knowledge of the morphology of the simple form of organisms does not suffice to differentiate the numberless more or less similar species. It is difficult and almost impossible to identify a distinct and constant type for each species, or recognize form-differences suitable for classification. Nor does it seem that culture methods have made possible systematic grouping, or the variety of tests needed for accurate and trustworthy comparisons. No necessity exists for doubting the value of cultural characters; it is merely maintained here that additional and new methods must be tried, and tests should be scrutinized from every standpoint. Though widely different in their behavior in culture media and in their relation to air, yet the pathogenic properties of the bacterial flora from the different plant formations and societies should be ascertained within the limits of their natural habitat, and should be deter- mined also with reference especially to the degree of functional inhibition on higher plants. It is not until a study is made of the special reaction of bacterial transformation products in sterilized bog water upon the growth of agricultural plants that the lack of salient features between habitat relations and physico-chemical reactions in artificial media becomes noticeable. Considerable difficulty was experienced in the isolation of organisms with the conventional media. In the majority of cases very little growth was obtained on beef broth gelatin or agar. Gelatin and agar media made with peat and bog plant juices proved more satis- factory for isolation purposes. Moreover, bacteria of rapid growth and early appearance of colonies on the artificial media 2 Since the observations herein recorded, the writer saa through the courtesy of Professor HARSHBERGER a paper published by Dr. D. Rivas on “Bacteria and other fungi in relation to the soil” (Univ. Penn. Publ. 3:243- ee 1910). It is cited here as bearing directly on the problem in hand. rgt1] DACHNOWSKI—CRANBERRY ISLAND ite) caused less retardation on the growth and transpiration of wheat plants when inoculated into sterilized bog water than bacteria of slow growth. In some cases the isolated pure cultures made little headway on beef broth or peat agar media after a period of 3-5 months, but gave strong inhibition in the growth of wheat plants within 3 weeks after inoculation into sterilized bog water from their respective plant zones. It is reasonable to assume, therefore, that the lack of uniformity in results implies both obligative symbiosis and the need of a physiologically balanced culture medium. The fact that the organisms are obligate sapro- phytes, capable of growing only on substrata similar in composi- tion to the character of the surface vegetation, is indicative of a close interdependence; their rapid growth in a medium in which cellulose and lignin compounds predominate suggests a specific cytohydrolytic action. Certain microorganisms in station III have been found to possess the ability to dissolve filter paper, but their isolation has not been successful. It is needless here to repeat the physiological tests which were made with a number of isolated pure cultures inoculated in ster- ilized bog water. Transpiration figures of wheat plants growing in these solutions and various other data have been published in an earlier paper (/.c. 9) to show the active participation of the organisms in the formation of bog toxins, and their ability to inhibit during the processes of denitrification and dehydration the growth of plants alien to the habitat. With these suggestions in mind, the results on the bacterial reactions in culture media submitted above may now be summarized as follows: Peat soils are very rich in bacteria inducing diastatic, inverting, proteolytic, cytohydrolytic, and reducing action. The organisms vary in kind and number with the nature of the substratum. The majority of the forms are found to thrive as saprophytes, digesting the débris in the upper layer of the peat substratum and aiding in a partial disintegration of the accumulating deposit. Many forms thriving as saprophytes among the indigenous flora give little aid in the elaboration of food eran to invading or introduced plants. 20 BOTANICAL GAZETTE {JULY The organisms show a marked interdependence between them- selves; one set of bacteria prepares a medium for another out of an unfavorable substratum, and this paves the way for others to continue the destruction. Signs are not lacking, however, of relative indifference and even antagonism among the organisms, resulting in products which retard and inhibit further bacterial growth and disintegration processes. A certain proportion of bacteria in these soils has the special ability to produce substances, perhaps unassimilable, certainly injurious to all but indigenous plants. In a peat substratum the percentage of bacteria aiding in the production of deleterious substances such as reducing bodies, gases, indol, and other fermentation products varies with the season of the year, but especially with the advance of the vegetation toward the closed deciduous forest formation. These bodies constitute the unsanitary conditions in soils, the negative factor which limits the rate at which the splitting up of organic compounds into ammonia and other assimilable substances proceeds. They are the character- istic symptoms of a diseased, sterile soil. The greater oxidation in the productive peat soil is due to the activity of a different set of bacterial organisms. The rédle which microorganisms play in the soil points, therefore, to the fact that among other things a considerable relation exists between the processes of disintegra- tion of organic material and the succession of plant formations in bogs and marshes, and in peat soil under cultivation. Each plant formation has its own bacterial flora maintaining a physiologically balanced condition in the soil. The substratum of each plant formation is an ever varying medium, the seat of physical, chemical, and vital activities which directly and indirectly influence its relative fertility and the character of the surface flora. Varying with the power of multiplication and metabolic activity is the quantity of the products of decomposition consti- tuting a toxic, physiologically arid habitat at one phase, and an available supply of nutrients to plants at another stage of the process. Acidity, toxicity, and reduction action represent merely a stage in the decomposition of organic matter. In the natural successions which ensue, each plant association augments the rgtt] DACHNOWSKI—CRANBERRY ISLAND oF efficiency of the soil as a habitat. The soil processes involved are an efficient natural process for the maintenance of relative productivity. Differences in the mineral components are — compared with the biological processes. The sum total of the reactions in any stage of the process exercises a physiologically selective function upon invading plants, furthering the growth of such plants whose roots are not merely absorbing organs, and excluding and eliminating all others in which the power to make extracellular changes in the soil is ineffi- cient. The significance of the data calls, however, for still further experimentation to be of sufficient evidence to assume a specific metabolism in bog plants, or to disclose the chemical nature of bog toxins. Origin of the habitat Initially the bog island was formed as are all bogs occurring in glacial moraines, or in depressions which form frequently in the gravel plains along the lines of drainage from the front of the glacial ice. Extensive acquaintance with peat bogs or a com- parative study of the lists of plants from different regions will convince any careful observer that bogs are very different in char- acter, and that not all of them have been formed in the same way. There may be a number of possible ways by which such accumu- lations of vegetable matter came about. Various such points of view and methods of classification have been suggested in a com- prehensive study by Davis (11). As the process of bog develop- ment here seems similar to that of the peat deposits which the writer has observed at Michigan, the following brief account is given. During the glacial period, most species common to bogs skirted the border of the ice sheet. Whatever plant or animal life existed “was confined to the highlands east of the Scioto Valley, south of the Ohio River, ‘and in the southern portion of this continent. At the margin of the ice sheet the conditions must have been quite circumpolar in character, similar to those of the barren grounds of the far north, that is, there prevailed short summers and long winters with frequent winds and storms. Whatever the causes 22 BOTANICAL GAZETTE [JULY that resulted in such climatic conditions (4) with their change and with the progressive northeastward movement of the ice, an increasing land area became exposed, the topography of which is even now largely the inheritance of that time. While yet the entire surface of northern Ohio and the land north of it was buried under the ice sheet, the region about Columbus and Buckeye Lake was among the first to be laid bare by the retreating ice and water. The receding of the ice sheet was paralleled by the north- eastward movement of more favorable weather conditions which initiated a migration northward of plants and animals along the glacial drainage channels, the earliest highways for the dispersal of many forms of life (1). As the ice and water continued to recede and the processes of erosion brought about better drainage and lower water levels, the flora and fauna followed down the slopes and began to encroach upon the ponds and lakes. The bog plants and their associates slowly had passed northward close to the base of the retreating ice, and hence were among the first to take possession of the new territory. As has been stated, the test borings make it evident that the bog vegetation grew out from the shores, forming a floating mat; that sphagnum and cranberry appeared after the sedges and rushes had built up the surface mat; that filling in of débris from the sides continued slowly until the water had become shallow enough in places to enable shrubs and trees to occupy the area. The later phases of mature bog forests the writer has met very frequently in Ohio, and several interesting localities have been studied in connection with an inquiry on the peat deposits made for the Ohio Geological Survey. ile it is not clear how the preservation of the local bog island has come about, the present investigation has led to the conclusion that a well marked relationship existed between the type of peat soil considered with regard to its degree of disinte- gration, and the succession of plant associations covering it. As elsewhere in Ohio today, the firmer and well decomposed peat strata were covered sooner with forests, and were built up rapidly by an attendant sinking and shrinkage of the mat under the added weight of the growth and fall of trees and the vegetation of suc- rgtt] DACHNOWSKI—CRANBERRY ISLAND 23 cessive seasons. On the other hand, the absence of logs and fallen timber in the peat of the sphagnum-cranberry zone points clearly to a relatively slow encroachment upon the open water by the plants. When inundation took place, only the coarsely fibrous and incoherent cranberry-sphagnum mat rose with the water level, and its vegetation survived. As late as 1830 the bog was an extension from the mainland. After the formation of the dike, and the consequent rise of the water level, most of the mainland became inundated, leaving the bog completely an island. With its surface vegetation of mostly northern forms, the island is virtually a water culture on a large scale. None of the plants are dependent for any important part of their food on the mineral soil below the peat. Cranberry Island is, therefore, not to be considered merely as a case of the conversion of a forest into a marsh under the influence of an increased water content in the soil. The analysis of peat samples shows that the vegetation now growing upon the peat substratum represents quite fully a continuation of the former boreal flora. It presents today a somewhat disjointed distribution, but this has come about chiefly through recent repeated disturbances in the water level of the lake, through a settling and shrinkage of the peat soil, through the slow encroachment of the invading southern vegetation, and through the formation in places of a better and firmer soil. The flora For convenience three well marked plant zones may be pointed : out, each of which is characterized by communities and groups of plants easily differentiated from the others. No attempt has been made to give full lists of plants, or to correlate the associa- tions and successions mentioned with similar conditions elsewhere. Essentially the same order of succession and of arrangement of plants as has been described for northern bogs is not, of course, to be expected. The species are not always the same in the corre- sponding formations, but they are systematically related and closely similar in ecological structure. A fuller floristic treatment is now in preparation, in which many of the features are described in detail. 24 BOTANICAL GAZETTE [yuLy THE BORDER ZONE The outermost growth which immediately borders the open water and forms a more or less broken fringe around the island is for the most part hydrophytic. Along the southern shore it is dominated by the swamp loosestrife (Decodon verticillatus) and in places by cat-tails (Typha latifolia and T. angustifolia). This facies has for its principal and secondary species Hibiscus Mos- cheutos, Sagittaria latifolia, Polygonum hydropiperoides, Ranun- culus pennsylvanicus, Scutellaria galericulata, Lathyrus myrtifolius, Bidens cernua, Potentilla palustris, Campanula aparinoides, Galium triflorum, Cicuta bulbifera, Peltandra virginica, and others. They are generally abundant, with Decodon and Typha forming a dense growth, which attains a height of 2-6 feet (0.6 to 1.8 m.) above the substratum. The vertical zonation is that of the differences in habit of growth of the individual species. The members differ widely from one another both in external features and in their demands upon the environment. In these regards the vegetative shoots adapt themselves little to the prevailing exposed conditions. Growing upon a peat substratum whose depth and physical char- acteristics are in every way like that of the other plant zones to be described below, the xerophytic type and quality are least marked in this vegetation. The well decomposed peat soil of the border zone permits here a luxuriant growth. The plants are able to secure all of their raw food materials from the water and air, and build their own substratum. The high water capacity of peat, the absence of a mineral soil, the smaller percentage of oxygen in the water, and the incoherency of the substratum afiord no precarious conditions for growth. Here the toxicity of the sub- stratum and the consequent physiological aridity are least marked. It is evident that dilution and the capacity of absorption of soluble salts by the humus soil along ue margin (8, p. 403; 9) corrects any harmful effect. The Decodon-Typha association has a transition appearance, for a considerable admixture of plants such as Rosa carolina, Cephalanthus occidentalis, Cornus canadensis, C. paniculata, C. stolonifera, Salix discolor, S. nigra, S. pedicellaris, Alnus incana(?), A. rugosa, Ilex verticillata, Prunus melanocarpa, Rhus Vernix, rort] DACHNOWSKI—CRANBERRY ISLAND 25 and various secondary dependent associates, occupy the firmer parts of the marginal zone and form an almost continuous fringe, the Alnus-Rhus association. In places it extends diagonally across the bog island as scattered dense thickets (fig. 4). This community of plants presents on the whole very little zonation within itself. It constitutes a zone of varying width, 5-30 feet (t.5-9 m.) and more, and attains a height of 8-12 feet (2.5-3.5 m.). Only in a few places along the southern shore this type of bog shrub formation is absent altogether and is replaced, as has been Fic. 4.—Map of Cranberry Island; surveyed February 1910; the divisions into plant societies as indicated by the map and the text are based on general characters of the vegetation; A, Decodon; T, Typha; the ponds on the island are shaded. stated, by Decodon and Typha. The edaphic conditions of this part of the habitat seem to approximate those of the undrained swamps as described by Cowtes (6). Nearer the lake there is a tendency toward the segregation of Decodon verticillatus and Hibiscus Moscheutos. Of the two, the former is more vigorous and occupies the deeper water. Rosa carolina prefers the outer border also, but clings quite closely to Alnus incana and Cornus stolonifera. Contemporaneous with the thicket-formers, various species of lianas invade the association. The mature thickets are often covered with an impenetrable growth of tangled vines of Apios tuberosa, Solanum Dulcamara, Convoloulus Sepium, Ipomoea sp., and Cuscuta Gronovii. Cephalanthus occidentalis does not 26 BOTANICAL GAZETTE [JULY constitute a large part of the shrub formation. Together with Decodon, it is found frequently indiscriminately mixed with facies in the central zone. In fact, the differences in the formation are to be seen largely in the ratios between the numbers of indi- viduals present, and not in their entire absence from either. THE MAPLE-ALDER ZONE With the maturity of the facies, a gradual change in the envi- ronmental conditions for the plants takes place. The annual leaf- fall covers the substratum with a visibly thicker layer of vegetable material rich in organic matter, and is followed by the growth of fungi and bacterial organisms favorable to succeeding plants through the formation of available nitrogen. Like snow and ice, the covering of fallen foliage reduces the extremes of soil temperature, suppresses the growth of Sphagnum, Oxycoccus, and similar plants from the adjoining central zone, and improves the production of a kind of humus of great significance to the animal life as well. Moles, earthworms, snails, and insects are not uncommon in this zone. The shade of the trees during summer and autumn checks extremes in evaporation, and thus reduces the transpiration from the herbs and shrubs beneath the trees. Through the combined action of these and various other agents, there is a corresponding rearrangement of some species and the disappearance of others. In places along the margin, the peat substratum is firmer, fairly well above the level of the lake, and comparatively better drained. These conditions are sufficiently established at the southeast side of the island to be characterized as the maple-alder zone. The bog tree formation is quite promi- nent, and though not extensive, it is still a strongly marked zone. The most conspicuous plants are large-sized maples (Acer rubrum), alders (Alnus incana, A. rugosa, Ilex verticillata), the chokeberry (Prunus melanocarpa), black cherry (Prunus serotina), and poison sumach (Rhus Vernix). Oaks (Quercus palustris, Q. imbricaria), ashes (Fraxinus nigra), and the silver maple (Acer saccharinum) are still relatively rare. The trees are surface-rooted. The roots do not penetrate to a depth of more than one foot (30 cm.). They spread out in all directions from the trunk, and are of sufficient 1911] DACHNOWSKI—CRANBERRY ISLAND 27 size and length to withstand the mechanical strains due to the action of air currents. The association is still an open commu- nity of plants and has four distinct vertical layers. The trees cast a relatively dense shade, in which grow seedlings and young trees of oak and maple, and a variety of shrubs and herbs. Most abundant are Sambucus canadensis, Impatiens biflora, I. pallida, Rubus sp., Dianthera ovata, Viola blanda, Aspidium spinulosum, Osmunda regalis, Carex scirpoides, Aspidium cristatum, Habenaria clavellata. There is protection from strong air currents, and in the changed light, heat, and moisture conditions the plants offer a striking con- trast to the vegetation next to be described. Many of the herba- ceous and shrubby species occur only sparingly, and are really constitutents of the other societies of the border zone. In the numerous maple and oak seedlings the evidences are seen that the Rhus-alder consocies will not continue to occupy the habitat. The lowering of the water table due to the continued addition of débris and leaf-humus will hasten the advent of better soil, drainage, and shade conditions. Almus and Rhus and their asso- ciates will find the new conditions unsuitable; they will disappear, leaving the zone more typically an oak-maple-ash formation. It is not probable that this coming society represents a climax forest for filled lake basins in this locality. There are limited portions on Cranberry Island which in the course of years are bound to revert to the central zone bog type, and that perhaps intermittently, for a settling and shrinkage of the numerous water pockets in the peat substratum will continue until all of the lower strata have become firm and compact. With continued accumu- lation of forest litter, the soil conditions will finally become drained and more xerophytic, to an extent that will constitute an ecologi- cal habitat considerably different from that existing in the neigh- borhood. Should the water level remain constant, the amount of upbuilding will be limited to the distance to which the water will rise through the accumulation of peat, and supply the growing plants at the surface with the necessary physiological water. It must not be assumed, therefore, that the development of a mesophytic forest could continue in the same direction indefinitely. 28 BOTANICAL GAZETTE [JULY It is the lack of moisture, and not low temperature that will arrest the growth and reproduction of the plants concerned, and the disintegrating action of fungi and bacteria. This factor in plant growth, not previously important to the plants of the sedge, shrub, and thicket growth, then becomes operative selectively, leading to the establishment of a xerophytic plant association. At present, however, there is little indication of the appearance of an association of that kind; the climatic trend favors broad- leaved forests, and the supposed physiographic characteristics leading to a xerophilous climax association assume nowhere on the island any considerable importance. There are conditions, however, which would indicate a rever- sion to a hydrophytic association. Adjoining the maple-alder zone on the southeast side are several extensive areas which do not respond quickly to changes in the water level; fig. 7 illus- trates a part of such an area. Through the accumulation of vegetable débris, the replacement of air and other gases held in the mat by water, but especially through the increased load upon the surface of the mat after the heavier tree association became established, a settling and shrinkage of the peat occurred, which ultimately resulted in the sinking of the mat several feet below the water level. The cutting of the timber reestablished equilib- rium and rejuvenation. The species now tenanting the mat in- dicate a tendency toward the development of a hydrophytic vege- tation approaching the type of the border zone described. The marked difference between the vegetation of the central zone and the one establishing itself is worthy of special note. Except such portions of the fibrous mat as were long ago broken off from time to time by the action of wind and waves and drifted about as floating islands, the rejuvenated “sunken” mats, and such areas as annually rise in the early summer and disappear again beneath the water in late autumn concomitant with the “‘over- turn”’ of the lake, show nowhere members of the cranberry-sphag- num zone. They illustrate most forcibly the fact that under these conditions a very different set of plants spring up and become dominant, although the true bog plants are near at hand. rgt1] DACHNOWSKI—CRANBERRY ISLAND 29 THE CENTRAL ZONE This zone is situated centrally on the island. It occupies the larger part of the area of the island, and in its floral structure is very distinct. The plants consist principally of Vaccinium (Oxycoccus) macrocarpon and several species of Sphagnum, with Rhynchospora alba, Eleocharis obtusa, Aspidium Thelypteris, Duli- chium arundinaceum, Carex comosa, Scheuchzeria palustris, Juncus canadensis, Eriophorum virginicum, Osmunda cinnamomea, Drosera rotundifolia, Menyanthes trifoliata, several orchids, and other light-demanding forms variously grouped. The surface is char- acterized by hollows and elevations. The latter are due, in the opinion of the writer, to various causes; in part to the upward growth of sphagnum competing with cranberry, in other places because of a mutual protection which is afforded by the massing of forms of a similar height against excessive loss of water. In still other places, cranberry and sphagnum are growing beneath shade-producing forms, notably around ferns and invading maples and sumachs. Here they possess the ability to grow up in a manner giving rise to a thick soft mass, raised to a considerable height, more at the center than at the periphery. The maximum height to which cushions of sphagnum can grow is limited by the vertical saturation gradient of the water content in the air. The vertical level of this vegetation is otherwise fairly uniform, and varies only between 6 inches (15 cm.) and 1.5 feet (45 cm.) above the peat substratum, forming a low, dense, compact growth. The taller growth of grasses and sedges and the occasional bushes of Gaylussacia baccata, Prunus melanocarpa, and P. arbutifolia occur chiefly scattered and as open facies. They do not dominate the general vegetation enough to interfere with the transpiring organs of the plants at the lower level. A more detailed study of the distribution of the species in the lower stratum shows habits of growth giving rise to vertical layers sufficiently defined to recognize vertical zonation; especially the differences of growth in height in the sphagnums, Gaylussacia, and Vaccinium in areas of varying physiological aridity show that the plants are adapted to a given average supply of water. But 30 BOTANICAL GAZETTE [JULY in the zone under consideration, the differences in habit of form shade into each other, and in consequence are less distinct than those in the adjoining border zones. The prevailing grasslike growth-form, the general reduction in size of leaves assumed by the different species, is in harmony with the environment. It expresses itself not only in external features but also in the ana- tomical structure. As an ecological unit, the community of plants, identical in type, but different in floristic composition, exhibits well within itself the impress of its conditions of life. Frc. 5.—A pond in the cranberry-sphagnum association; Decodon is the most important mat former making the advance upon the water. Differences in aerial functions would be therefore largely species characteristics as well as environmental. That the plants are adapted to a given average supply of avail- able water, but with great specific differences among themselves, is further seen in the frail growth of Cephalanthus and Decodon, in the small trees of Acer rubrum and Rhus Vernix, and in the stunted forms of various other invaders from the neighboring plant societies which occur scattered throughout this zone. For the past few years thousands of maple, sumach, and alder seedlings have been observed to sprout, and yet failed to succeed beyond the first year’s growth. Of those which succeeded, the stunted growth, the numerous dead branches, the ragged crown of foliage, tg1t] DACHNOWSKI—CRANBERRY ISLAND i are a clear instance of the fact that the resistance offered by the invaders to the toxic conditions of this habitat is, indeed, but slightly effective. There are several small ponds in the cranberry-sphagnum zone in which the dominance of Decodon and Typha as important members of the border vegetation is especially to be noted (fig. 5). Decodon is particularly well adapted in making an advance out- Fic. 6.—The last stage of a larger water area, now occupied by the advancing cranberry-sphagnum association. ward upon the water by the manner in which the slender mature stems, that bend toward the water, curve at the tips. From the submerged part roots arise in considerable numbers, buds form, and new plants develop. The young plants remain moored to the parent plant for a year or two. As soon as the stools are built, they become the habitat of a number of plants such as Bidens cernua, Polygonum hydropiperoides, Cyperus strigosus, Impatiens biflora, Peltandra virginica, and others. These with Decodon and Typha seem, however, unable to persist, for dead stems of Typha and remains of stools of Decodon may be seen in 32 BOTANICAL GAZETTE [JULY the cranberry-sphagnum association immediately behind this border vegetation. The last stage of a former large water area now occupied by the advancing cranberry-sphagnum association is shown in fig. 6. Cranberry and sphagnum build a mat and tufts of great compactness and gradually overcome and eliminate the swamp loosestrife (Decodon), cat-tail (Typha), Peltandra, and others. The advance of the mat out over the surface, even of open water, can be demonstrated by a series of such stages and Fic. 7.—A sunken mat in the process of rejuvenation; the increased load upon the ile of the mat, especially after the heavier tree association became estab- lished, caused the sinking of the mat; the cutting of the timber reestablished equilib- rium. “last vestiges’? indicating the existence of concentric zones of Decodon and Typha in quaking mats where formerly water occu- pied the area (fig. 4). The mats are floating, for test borings through them end abruptly in water which is quite free from fibrous material. The space of open water between the upper mat and the rest of the deposit below has frequently a depth of 4-5 feet (1.2-1.5 m.). In several places the peat below such mats is fine grained and well decomposed, not at all of a character that would indicate a transition structure from the coarsely fibrous to the well disintegrated, slightly fibrous deposit resting on the coarser mat below. Igri] DACHNOWSKI—CRANBERRY ISLAND 33 The sphagnum-cranberry formation is not to be regarded as an intercalation (18). The organic matter deposited by past generations of plants shows that sphagnums, cranberry, and their associates occupied this surface long before the maple-alder zone was formed. It is therefore an earlier and normal stage of suc- cession, under conditions of development and a combination of factors which favored persistence and succession in that direction, and which are not suitable even today for the ecesis of a shrub- formation or for germination and growth of the seeds blown over in great quantities from the woodlots and fields surrounding the lake. The vegetation in the central zone agrees very largely with plant societies in bogs and swamps of more northern regions. Many other ‘‘boreal”’ plants which were no doubt concerned in the early developmental stages of the local bog are now extinct. This is especially true of the pitcher plant (Sarracenia purpurea), the creeping snowberry (Chiogenes hispidula), wild rosemary (Andromeda polifolia), leather leaf (Chamaedaphne calyculata), labrador tea (Ledum groenlandicum), pale laurel (Kalmia polifolia), and larix (Larix laricina). The plants are still found in Ohio bogs north of here. A number of them have been recently transplanted and are now on the island in good condition. Ouro STATE UNIVERSITY CoLumBuS, OHTO A MORPHOLOGICAL STUDY OF DIOSPYROS VIRGINIANA CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 145 STELLA M. HAGUE (WITH PLATES I-III) Diospyros virginiana, the northernmost representative of the tropical family Ebenaceae, grows abundantly in the southern states and as far north as the southern part of Illinois and Indiana. Cultivated trees are found also in the extreme northern part of those states. No report of any morphological work upon this family has been found, except a brief paper on “The seedless per- simmon”’ in the report of the Proceedings of the Indiana Academy of Science for 1908. The material for this investigation was col- lected in 1906 and 1908 from cultivated trees at Decatur (Illinois), and from native trees near Springfield (Missouri), Topeka (Kan- sas), and Memphis (Tennessee). Floral development The winter buds are composed of numerous tough hairy scales enveloping a very rudimentary shoot. The flower buds develop upon this shoot during its rapid growth in the spring. At Decatur, in 1906, the buds began to swell and to become green the latter part of April. Young shoots gathered the first week in May bore flower buds in the early stages of development. On May 30 the shoots were 20 cm. or more long and the flowers were beginning to open. _ So far as the trees from which material was collected were observed, they were dioecious and bore only imperfect flowers. One possible exception has been found recently. Near Auburn (Indiana) there is a cluster of staminate trees, originating appar- ently from one tree, that are reported to have borne fruit occa- sionally. The flowers were carefully examined in the spring of 1gto, and no variations from the regular staminate type were found. Unless a pistillate tree has been cut away, it seems prob- Botanical Gazette, vol. 52] (34 tgtt] HAGU E—DIOSPY ROS 35 able that perfect flowers are borne some seasons, as has been re- ported from Kansas." The staminate flowers are smaller than the pistillate and in clusters (fig. 1), 16 fertile stamens surrounding the sterile pistil. The pistillate flowers are solitary, and usually contain 8 sterile stamens, but very often the number is greater. The early stages of the development of the two flowers are the same. The floral cycles are generally preceded by a pair of bracts, though often there is only one (fig. 2). The calyx next appears (fig. 3) and becomes a massive enveloping cup before the other cycles can be seen, which appear in centripetal sequence (fig. 4). The corolla can be distinguished before the stamens, but they develop together in the typical sympetalous fashion. Occasionally the calyx or corolla has more than four parts; this is illustrated in fig. 6, in which the calyx has five divisions. The stamens of the staminate flower fork (fig. 5), thus doubling the pistillate number (fig. 6); in the pistillate flower it is a common occurrence to find the number increased by the branching of one or more of the stamens. The fertile pistil contains eight ovules. The style is single, but the stigma is four-parted. Not many sterile pistils were examined; those that were had no ovules and a short imperfect style. Megasporangium and megaspores The ovule is anatropous and has two integuments (fig. 7), this last character being unusual among the Sympetalae. The mother cell can be distinguished by its size and conspicuous nucleus about the time the inner integument is first visible (fig. 8). Judging by the repeated appearance of this stage in the material, it is espe- cially persistent. Only one mother cell occurs in a sporangium, and is always next to the outer layer of nucellar cells, no parietal cell being cut off. One complete figure of the first division of the mother cell was found in the spindle stage (fig. 9). Compared with the preceding conspicuous nucleus of the mother cell, the spindle is small and has very small and numerous chromosomes. * The Industrialist, Kansas State Agricultural College, March 1904. 36 BOTANICAL GAZETTE [JULY A portion of another figure showing the formation of the wall between the daughter cells was seen. Four megaspores are formed in a linear row (figs. ro, 11), but it is not always complete, three cells not being uncommon. One exception to the usual arrangement was discovered, in which the outer daughter cell is divided by a vertical wall (fig. 12). As usual, the chalazal megaspore becomes the embryo sac (fig. 13). Early stages of the embryo sac The two and four-celled stages of the embryo sac were not found. At the eight-celled stage the sac is small, much longer than wide, and somewhat pointed at the micropylar end. When the sac is seen enveloped by the single nucellar layer, it appears decidedly cone-shaped, and is supported upon a stalklike portion of the nucellus as upon a pedestal (fig. 15). The growth of the sac does not obliterate this nucellar tissue until a comparatively late stage of the ovule. In the sac of fig. 14, which is the eight- celled stage in which the polars are differentiated, only seven nuclei are shown, and it seems quite probable that that is the full number for that particular sac, because there is much evidence that the usual number of nuclei is not always present. This con- clusion is reached because of the conspicuous absence of antipo- dals. Three antipodals were found in one sac, but only after a long search. Extremely early disintegration would also account for the absence of these cells, but no evidence was found for this explanation. The egg apparatus in the eight-celled stage shows nothing unusual. The three cells are in the ordinary position, and there is the customary differentiation of the cells in size. In striking contrast to these two groups, the antipodals and egg apparatus, are the polars, which are large and conspicuous (figs. 21a, 216), and are found either approaching or fusing in material gathered during the flowering time. During the development of the sac the integuments become massive, and the innermost layer of cells of the inner integument becomes large and full of protoplasm, forming a tapetal layer com- ro1t] HAGUE—DIOSPY ROS 37 pletely enveloping the sac and extending around the stalklike nucellus and far up the micropyle (fig. 16). The study of the sac is made difficult by the dense outer integu- ment, through which killing fluids penetrate with difficulty, and also by the presence of chemicals which interfere with the stains. This last difficulty is especially true of the micropylar end of the sac, which when mature becomes a beaklike accumulation of a mucilaginous substance. Pollination and fertilization These studies have so far revealed only doubtful evidence of pollination and none at all of fertilization. Careful search has failed to show pollen tubes in the tissue of the style. The most positive evidence has been a few cases in which the mucilaginous substance has been divided in such a manner as to suggest a pollen tube penetrating the sac, and a few others in which there is the appearance of a swollen tip of a pollen tube within the sac. This evidence is discredited because the mucilaginous substance has been seen similarly divided too early for pollination, and the resemblance to the swollen tip of a pollen tube may be due to an incomplete or imperfect section of the stage shown in figs. 17a and 176. Other slight evidence may be found in the presence of the spindle and chromosome-like bodies of figs. 19 and 20b. These may possibly have entered the sac by way of the pollen tubes or may have originated from the nuclei of the tube. The fusing polars which are so conspicuous have been carefully examined for a third nucleus but none has been seen. The doubtful character of this evidence has naturally raised the question, whether pollination is essential to fruit and seed produc- tion. The field observations relating to pollination are limited and not very exact, but they suggest the possibility of an interesting problem. A tree in Decatur, from which material was collected in 1906, bears seeded fruit abundantly, though no staminate tree is known to be nearer than two miles. In order to see if the pollen was carried that distance or was essential, a branch was covered in the spring of 1909 during flowering time so as to prevent the 38 BOTANICAL GAZETTE [JULY access of the bees. No fruit was borne on this branch, but was developed upon the neighboring ones. The details of this experi- ment cannot be vouched for, but until more careful ones are tried it is affirmative evidence for pollination. On a fruit farm beyond the city limits of Decatur is a cluster of 6 or 8 trees, the largest of which is the parent of the smaller ones. The gardener reports that seedless fruit occurs on all these trees, but not in the same proportion. The fruit of the largest tree is usually many-seeded and only rarely seedless, but some of the smaller trees bear few-seeded and seedless fruit abundantly. No differences were noted among the flowers of these trees, or any when the prepared material was compared with that from native trees. The later stages are yet to be examined, for no collections have been made from the cluster after the flowering time. The nearest staminate tree is not known. One was reported within a quarter of a mile, but two careful examinations of the region have failed to locate it. Since persimmon trees in bloom always swatm with bees, they are doubtless the pollinating agent. It does not seem probable that the bees avoid certain trees, but it is possible that the supply of pollen which they carry is limited, and is deposited most freely on those trees which from their posi- tion they visit first. The trees of the cluster which bear the larger proportion of abnormal fruit are the least exposed trees. That the distance of the staminate trees does make a difference in the fruit is reported in the 1907 Yearbook of the Department of Agriculture, in which one variety is mentioned as characteris- tically few-seeded, and the observation made that this and other varieties have fewer seeds when grown at a distance from staminate trees. In r910 the Decatur trees were again visited. A severe frost in May killed the first buds, consequently the conditions that season were not normal. The city trees bore no fruit at all, and the cluster only a small proportion of its normal amount. The fruit on all the trees was smaller than usual, inclined to early decay, and almost wholly seedless. One lot of 33 contained only one seeded-fruit; another of 12, two. The embryos were normal. This state of affairs suggests an indifference to fertilization, even 1911] _HAGUE—DIOSPY ROS 39 to pollination, as the stimulating cause of the development of the ovary into the characteristic persimmon fruit. In the paper previously referred to on “The seedless persimmon,” the seedless fruit is reported to occur most abundantly on the lowest branches of the trees. No differences were found in the flowers; all had a fertile pistil and sterile stamens. The examina- tion of the embryo sacs brought out no evidence of pollination or fertilization. In one case cited, if pollen is transferred from the staminate trees, the bees must carry it three or four miles; this was not determined. Perfect flowers are suggested as a possible source of the pollen. Any attempt to explain or to suggest the problems of pollination involved is impossible until further obser- vations are made. Late stages of embryo sac; endosperm and embryo The absence of evidence of pollination and fertilization has made impossible at present a connected account of the series of events in a normal seed-producing sac following the eight-celled stage, nor can these stages be surely identified, because the ovules of the seeded fruit frequently fail to develop into seeds, and since the normal course has not been determined, it is uncertain where the two diverge and what the differences are. The entire ovule increases very rapidly in size after the corolla falls off, but no sign of an embryo was found for a number of weeks afterward. Material sent from Memphis is past blooming the latter part of May, but not until the last of June or the first of July can embryos be found easily in the fresh material. Long before this the sac has become densely filled with endosperm. Judging from the size of the sac, the first division of the primary endosperm nucleus follows closely on the fusion of the polars, and the other divisions follow rapidly after this (figs. 22, 23a, 236). The antipodal nuclei disappear after the eight-celled stage, but the micropylar nuclei undergo interesting changes. In fig. 17@ there are three protoplasmic masses very distinctly differen- tiated. The middle one contains numerous, rather large, spheri- cal, densely staining bodies. Because of its size, position, and 40 BOTANICAL GAZETTE [JULY persistence in older sacs, this mass is surely the egg and the two other masses the synergids. Fig. 17) is another view of the same sac and shows the synergids more distinctly. Fig. 16 undoubtedly shows the two synergids, but no division of the sur- rounding protoplasm. In fig, 18 the egg appears with the spheri- cal bodies regularly arranged; the small nucleus is a synergid. Fig. 19 is the micropylar end of a sac in which figures of dividing endosperm nuclei were seen. The large cell is the egg, near which are the spindle-shaped figures mentioned before. From their position it is possible that they are the remains of the disintegrat- ing synergids. The large cell of fig. 24 is the egg at a later stage than the other figures show, because it is almost completely envel- oped by the endosperm; numerous illustrations of this stage were found. No more distinct segmentation of the egg was seen than appears in fig. 25, in which the protoplasm is divided, but only one nucleus could be found, which makes it a doubtful case. Even after the egg is completely surrounded by endosperm, the deeply staining globules remain, but they and the whole egg seem to lose the prominence shown in fig. 24. However, this is partly relative owing to the increased size of the whole ovule. Figs. 20a and 206 show the curious chromosome-like bodies in the micropylar end of the sac; they are rodlike and twisted, resembling chromosomes, but not those of Diospyros, which are very small. The investiga- tion of these phases of the life history of the persimmon will be continued in the hope that the complete sequence of events in the embryo formation will be found. The youngest unmistakable embryo that has been seen consists of three cells (fig. 26). This embryo was in the extreme micro- pylar end of the sac, imbedded in endosperm. Its position agreed very nearly with that of the egg when surrounded by endosperm, but no proof could be found that it originated from that cell. Fig. 27 represents the embryo at a much later stage, but does not yet show differentiation into stem tip and cotyledons. Fig. 28 is a variation from the common type, and fig. 29 is the appear- ance of the embryo about the time it can be distinguished without a lens. One case of polyembryony was found (fig. 30), and one lot of material contained freak embryos, one of which is shown in r9t1] HAGU E—DIOSPY ROS 4I fig. 31, in which a second pair of cotyledons has developed upon one of the original pair. Microsporangium and pollen The studies of the stamens and pollen were made from material collected in 1906 from a single tree near Decatur. This tree bloomed a few days later than the pistillate trees from which collections were being made at the same time. The pollen forma- tion was easily traced. The only difficulty encountered was in the late stages when the protoplasm is dense and evidently con- tains the same chemicals that interfere with the stains in Pus embryo sac. Each stamen produces four sporangia, whose early stages were not traced because the earliest collections were made May 28, about a week before the flowers opened. At that date the spo- rangia contained large pollen mother cells surrounded by a single tapetal layer (fig. 33). The division into tetrads is shown in figs. 34 and 35. The figures are small and the chromosomes numerous, 30 at least. In the mature pollen grain more than one nucleus could be rarely distinguished, and that one not nearly so conspicu- ous as the nucleus of the tetrad (figs. 36, 37). It is very possible that the dense protoplasm frequently obscures the second small nucleus. A considerable difference in the size of the pollen grains was noted; this and the frequent presence of a single nucleus, together with the lack of proof of pollination, raise the question of the fertility of the pollen. This remains to be determined along with the other problems of pollination. Summary 1. The flowers are developed on shoots of the same season’s growth. The floral cycles appear in the following order: a pair of bracts, the calyx, the corolla and stamens, and lastly the pistil. 2. The ovule is anatropous and has two integuments. A single mother cell is formed beneath the outermost layer of the nucellus, from which four megaspores develop, the chalazal one becoming the embryo sac. 42 BOTANICAL GAZETTE [JULY 3. The embryo sac at the eight-celled stage is small, somewhat pointed at the micropylar end, and rests upon a stalklike portion of the nucellus. A tapetal layer of cells from the inner integument completely surrounds it. The egg apparatus in this stage is not conspicuous; the polars are large and striking in appearance; the antipodals are found with so much difficulty that it. is probable that one or more of the cells is often lacking. 4. The studies of pollination and fertilization are not complete. Little evidence of pollination has been found and none of fertili- zation. The production of seedless fruit is probably involved in the problem of pollination. 5. After the flowers fall, the whole ovule increases rapidly in size. The egg enlarges and becomes filled with densely staining globules. The primary endosperm nucleus divides early and the endosperm fills the sac, and then crowds the inner integument quite up to the dense outer one. 6. The embryo is late in appearing. The earliest stage identi- fied was a three-celled one in the extreme micropylar region. The tendency to variation seen in many of the stages is shown here in the two types found, the freak embryos and the case of poly- embryony. 7. Pollen mother cells were found on a tree a week before the older flowers opened. The mother cells are large and the whole mass is surrounded by a single tapetal layer. The spindle in the tetrad formation is small, the chromosomes being 30 or more. The pollen grains show some difference in size, and frequently only one nucleus could be distinguished. I am very much indebted to Professors Joun M. Courter and CHARLES J. CHAMBERLAIN for assistance in the preparation of this paper, and also to the many friends who have so generously supplied me with material. AUBURN, Inp. tort] HAGUE—DIOSPY ROS 43 EXPLANATION OF PLATES I-III Fic. 1.—Diagram of a cluster of staminate buds. Fic. 2.—A pistillate bud, showing enveloping bracts (6). Fic. 3.—A pistillate bud, showing a single bract (>) and the beginning of the calyx. Ic. 4.—A pistillate bud, showing calyx (k), corolla (c), stamens (s), and pistil (f). Fic. 5.—A staminate flower, showing calyx (k), corolla (c), the two stamens (s), and pistil (). Fic. 6.—A cross-section of a pistillate flower, showing the unusual division of the calyx into five parts, the union of the corolla, and the four parts of the pistil; diagram Fie. 7. hi ovule with the two integuments. Fic. 8.—The nucellus containing the mother cell, and sowie the begin- ning of the inner integument (7). Fic. 9.—First division of the megaspore mother cell. Fic. 10.—The two daughter cells. Fic. 11.—The four megaspores Fic. 12.—The four ibis the outer daughter cell divided by a vertical wall. Fic. 13.—The functioning megaspore; the others disintegrating. Fic. 14.—Embryo sac; polars differentiated. Fic. 15.—Diagram of an ovule showing the relative size of the parts, the shape of the sac (e), the stalklike nucellus (), and the massive integuments (7). Fic. 16.—The micropylar end of the embryo sac, showing the synergids and the enveloping tapetal layer. 1G. 17a.—Micropylar end of sac; synergids and egg. Fic. 176.—Same sac as 17a, showing fusing polars. Fic. 18.—Micropylar end of sac; one synergid and the egg. Fic. 19.—Micropylar end of sac; egg and spindle-shaped bodies. Fic. 20a,—A detail of the micropylar end of a sac, showing the chromosome- like bodies and the egg filled with the densely staining globules. Fic. 20b.—Same as 20a; chromosome-like bodies more clearly shown. Fic. 21¢,—F using polars. Fic. 21b.—Fusing polars. Fic. 22.—First division of the primary endosperm nucleus. Fic. 23a.—Division of endosperm nucleus. — Fic. 23b.—Division of endosperm nucleus. Fic. 24.—Egg almost surrounded by endosperm. Fic. 25.—Egg; segmentation suggested. Fic. 26.—Young nee Fic. 27,—Young emb: Fic. 28.—Variation of ae of embryo. 44 BOTANICAL GAZETTE [JULY Fic. 29.—Shape of embryo at the time it can be seen without a lens; diagram. Fic. 30—Polyembryony; dia Fic. 31.—A freak embryo; a ond embryo (c?) developing on one of the first pair of cotyledons (c*); dia; Fic, 32.—Diagram of a scab ectina of an wather, showing the four spo- rangia. Fic. 33.—Pollen mother cells. Fic. 34.—Formation of tetrads. Fic. 35.—Tetrads Fic. 36.—Pollen grain; one nucleus. Fic. 37.—Pollen grain; two nuclei. PLATE I _ BOTANICAL GAZETTE, LII HAGUE on DIOSPYROS — PLATE II Tete, HAGUE on DIOSPYROS CAL GAZETTE, LIT r + z STS ae ee EP Lee he RE So ere a ee a ee eer STCAL GAZETTE, LIT HAGUE on DIOSPYROS UNDESCRIBED PLANTS FROM GUATEMALA AND OTHER CENTRAL AMERICAN REPUBLICS. XXXIV" Joun DonneEtt’ SmitH Thouinia brachybotrya Donn. Sm.—Folia petiolo parum longiora trifoliolata, foliolis ovato- vel obovato-ellipticis utrinque acutis crenulatis supra puberulis subtus velutinis. Racemi axillares singuli simplices tenues breves densiflori. Samara subsemicircularis, alae latere interiore axin centralem 3-plo super- ante, exteriore loculum eee Arbor 5-metralis, li li i til Foliorum juvenilium tantum visorum petiolus 1-2.5 cm. longus, foliola 4-5 cm. longa 16-20 mm. lata pellucido-reticulata, nervis lateralibus utrinsecus 10-12 furcatis marginem attingentibus, petiolulis 1 mm. longis. Racemorum pedunculus 3—6 mm. longus, rhachis 15-22 mm. longa vix 1 mm. crassa, pedi- celli e nodulo piloso squama transversim elliptica intus glabra cincto orti 3-4 mm. longi rubiginosi. Sepala 1.5 mm. longa intus glabra. Stamina 1.5 mm. longa, filamentis inferne pilosiusculis, antheris glabris. Ovarii cano-velutini lobi subrhomboidei 2.5 mm. longi apice obtusi axin centralem subaequantes stylum trifidum inferne cano-velutinum paulo superantes. Samara abortione saepe solitaria 20 mm. longa to mm. lata velutina tota flabellinervata, alae latere interiore recta, exteriore arcuata, axe centrali incana 5 mm. longa, loculo 6 mm. longo, semine ovali 4.5 mm. longo, testa ferruginea. Petala in exemplis suppetentibus deficientia. d ripas fluminis Rio Grande dicti, Depart. Zacapa, Guatemala, alt. 230 m., Jun. 1909, Charles C. Deam, n. 6343. Calopogonium phaeophlebium Donn. Sm.—Foliola elliptico- oblonga utrinque obtusa vel obtusiuscula supra pilis appressis conspersa subtus praeter nervos primarios fulvescentes cano- sericea. Racemi pedunculati foliis longiores remote nodiferi, floribus 1-s-nis subsessilibus minimis.. Calycis segmenta tubo paulo longiora. Vexillum calyce parum longius. Legumen fulvo- strigillosum gracillimum polyspermum. Herba volubilis, caulibus petiolis racemis retrorsum fulvo-pilosis. Foliola membranacea discoloria 5.5-8.5 cm. longa 2-3 cm. lata mucronulata, lateralia * Continued from Bor. GAZETTE 497458. 1910. 45] [Botanical Gazette, vol. 52 46 : BOTANICAL GAZETTE [yoLy paulo minora inaequilatera subsessilia, nervis lateralibus serve 7-8 rectis — marginem attingentibus subtus conspicuis, iolo communi 25 m. longo, petiolulo terminali mm. longo, sa ee SEB minute aie Racemi pedunculo 2-5 cm. longo computato cm. c longi, pedicellis vix 1 mm. longis, bracteolis minute sctaces, oe 7 mm. q ongum alis carinisque — lamina fere orbiculari 3 mm. lata exauriculata. Stamen vexillare omnino liberum. arium sericeum, stylo ad medium sensim incrassato. Legumen (in exemplis suppetentibus nondum satis maturum) deflexum lineare 5 cm. lon; mm. latum rectum apice falcatum, seminibus onn, Sept. 1893, Heyde et Lux, n. 6096 ex Pl. Guat. quas ed. Donn. Sm.—Secanquim, Depart. Alta Verapaz, Guatemala, alt. 570 m., Jan. 1905, George P. Goll, n. 226.—Rfo Torres, San Francisco de Guadalupe, Prov. San José, Costa Rica, alt. 1170 m., Nov. 1894, Adolfo Tonduz, n. 8968. Exemplum Gollianum in herbario Musei Nationalis sub numero proprio 860576 servatur. Hauya (§ SESSILIFLORAE) microcerata Donn. Sm. et Rose.— Folia longiuscule peticlata obovata vel oblongo-obovata supra glabrescentia subtus cinereo-tomentosa. Flores inter maximos. Calycis laciniae tubo bis et ultra superatae pro rata brevissime appendiculatae. Capsula dorso ecarinata. Arhueciula aechadala ‘T' 1-1 12 WW Peet Pe ‘4 co canoque pubescentibus. Folia primum ovallk supra premieres demum igi cm. longa 4-6 cm. lata abrupte breviterque cuspidata basi acuta venulis longae, appen 3-4 mm. longa cano-velutina. Petala ovalia 33 mm longa 23mm. lata. Antherae 18 mm. longae filamentis aequilongae. Ovarium patule cano-velutinum 1r mm. longum, stigmate elliptico 5 mm. longo supra la vix exserto. Capsula 5 cm. longa, seminibus deficientibus. Santa Rosa, Depart. Baja Verapaz, Guatemala, alt. 1500 m., Sept. 1888, H. von Tuerckheim, n. 1423 ex Pl. Guat. etc. quas ed. Donn. Sm. (Typus).— Cuesta di Quililh4 prope Purul4, Depart. Baji Verapaz, Guatemala, alt. 1400 m., Apr. 1905, H. Pittier, n. 155.—Canjob, Prov. Chiapas, Mexico, alt. 135° m., Maj. 1904, E. A. Goldman, n. 923. Exempla nn. 155 et 923 in herb. Musei Nationalis servantur. ror] SMITH—PLANTS FROM CENTRAL AMERICA 47 Hauya (§ SESSILIFLORAE) quercetorum Donn. Sm. et Rose.— Folia ex orbiculari-ovali ovata cuspidata vel saltem acuta basi rotundata vel emarginata supra glabra, costa nervisque subtus ciliatis vel glabrescentibus. Calycis laciniae tubo subdimidio breviores longe appendiculatae. Ovarium pubescens. Capsula inter minores. E schedula repertorum arbor. Ramuli glabrescentes foliorum cicatricibus arcte notati, partibus novellis cano-hirsutis. Folia subtus plerumque glauca cm. longa 5-6.5 cm. lata, nervis lateralibus utrinque 8-9, petiolis pilosis ca Bipinde I.5-2.5 cm. longis, stipulis aristuliformibus vix 1 mm, longis puberulis. Calycis oeltatoacl vel glabri tubus 7-9 cm. longus, laciniae 3-5-5 cm. longae, appendicula 10-13 mm. longa pubescente vel glabra. Petala 3 cm. longa. Filamenta 24 mm. longa antheris dimidio longiora. Ovarium 10-11 mm. longum, stigmate ellipsoideo 5 mm. longo paulo exserto. Capsula 3.5 cm, longa, valvis dorso planis, seminibus lanceolatis 15 mm. longis 5 mm. latis acutis, ala basi involuta incrassata latere altero producta Guatemala, alt. 1850 m., Mart. 1893, Heyde et Lux, n. 4479 ex Pl. Guat. etc. quas ed. Donn. Sm. (Typus); Dec. 1892, Heyde et Lux, n. 4336 ex Pl. Guat. etc. quas ed. Donn. Sm. Hauya (§ SESSILIFLORAE) ruacophila Donn. Sm. et Rose.— Folia orbiculari-cordata vel basi rotundata ovalia cuspidata supra glabra subtus costa nervisque dense cano-ciliata ceterum pilis deciduis conspersa. Calycis laciniae tubo subdimidio breviores appendicula elongata cano-ciliatae. Ovarium velutinum. Cap- sula inter majores. Arb diocri li llis velutinis. Folia 5-7 cm. longa 3-6 cm. lata, nervis lateralibus late patulis arcuatis utrinsecus 7-8 et costa subtus conspicuis, petiolis 12-25 mm. longis hirsutis vel velutinis, stipulis aristiformibus 2 mm. _ longis pubescentibus. Calycis pubescentis tubus 9.5-10 cm. longus, laciniae 5-5.5 cm. longae appendicula 1o-12 mm. longa instructae. Petala elliptica 4.5 cm. longa 2.5 cm. lata. Filamenta 25 mm. longa antheris subaequilonga. Ovarium 13-15 mm. longum, stigmate globoso 8 mm.-diametrali vix exserto. Capsula 6 cm. longa, valvis dorso planis, seminibus oblongis 13 mm. longis 4 mm. latis obtusis, ala basi involuta incrassata latere altero producta. In silvis ad montem Volcén Acatenango dictum, Depart. Zacatepéquez, Guatemala, alt. 1700 m., Mart. 1892, John Donnell Smith, n. 2528 ex Pl. Guat. etc. quas ed. Donn. Sm. (Typus).—Alotenango in declivitatibus praeruptis montis Volcén di Fuego dicti, Depart. Zacatepéquez, Guatemala, alt. 1300 m., Mart. 1892, John Donnell Smith, n. 2527 ex Pl. Guat. etc. quas ed. Donn. Sm. 48 BOTANICAL GAZETTE [JULY Hauya (§ SESSILIFLORAE) lemnophila Donn. Sm. et Rose.— Folia oblongo-ovata vel -elliptica vel -obovata cuspidata vel saltem acuta basi rotundata vel obtusa supra glabrescentia subtus hirsuta. Calycis laciniae tubo subtriente breviores, appendicula pro rata longissima. Filamenta antheris dimidio longiora. Ovarium hir- sutum. Capsula maxima. E schedula repertorum arbor. Ramuli foliorum subtus nervi petioli uti ovarium patule cinereo-hirsuti. Folia maxima subcoriacea circumscriptione summe Vv: oeuatans a Limghenios oblongo-elliptica g-15 cm. longa 4.5-7.5 cm. la nervis lateralibus subrectis utrinse- S 7-9, eae iolis : 2.S-4 cm. nail stipulis aristiformibus 2 mm. longis pubes- pone ad Flores e schedula albi. Calycis tubus 7.5-9 cm. longus, laciniae m longis. Ovarium 13-14 mm. longum, stigmate vix exserto. Capsula.lineari- oblonga 7.5—-8 cm. longa, valvis dorso planis, seminibus deficientibus d ripas lacus Carrizal dicti, Depart. Santa Rosa, Guatemala, ait 1360 m., Maj. 1892, Heyde et Lux, n. 2936 ex Pl. Guat. etc. quas ed. Donn. Sm. Hauya (§ PEDUNCULATAE) lucida Donn. Sm. et Rose.—Praeter foliorum nervos subtus glabrescentes omnibus in partibus glaber- rima. Folia nitida obovata vel elliptica cuspidata basi acuta. Pedunculus ovario brevior, flore inter minores. Calycis laciniae tubo triente breviores, appendicula brevi. Arbor 8-10-metralis, coma globosa aut dilatata. Folia juniora nervis subtus puberula, aetate provectiore glabra punctulato-pellucida 8-13 cm longa 4.5-6 cm. lata, nervis lateralibus utrinsecus 8-9, petiolis 1. 5—2.5 cm. longis, stipulis aristuliformibus aegre 1 mm. longis glabris. Pedunculus 4-7 mm. longus. Calycis tubus 4-6 cm. longus, laciniae 3-4 cm. longae, appen- dicula 3-4 mm. longa. Petala 3 cm. longa. Filamenta 17-19 mm. longa, antheris 20-23 mm. longis. Ovarium 9-12 mm. longum, stigmate supra petala paulo exserto. Capsula 3-4.5 cm. longa, valvis dorso planis, seminibus : oblongis 11 mm. longis 3 mm. latis obtusis, testa 4 mm. longa, ala basi involuta incrassata latere altero producta. Costa Rica, Prov. San José: Rio Torres, San Francisco de Guadalupe, alt. 1170 m., Jun. 1893, Ad. Tonduz, n. 8005 (Typus); Apr. 1894, John Donnell Smith, n. 4801 ex Pl. Guat. etc. quas ed. Donn. Sm.; Oct. 1898, Ad. Tonduz, n. 7445 ex Pl. Guat. etc. quas ed. Donn. Sm.: Rio Tiliri, Alajuelita, alt. 1000 m., ae 1894, Ad. Tonduz, n. 8915: Rio Virilla, San Juan, alt. 1000 m., Aug Sigh A d. Tonduz, n. 7285 ex Pl. Guat. etc. quas ed. Donn. Sm.: San tok Nov. 1898, H. Pittier (numero deficiente). 1gtt] SMITH—PLANTS FROM CENTRAL AMERICA 49 Hauyae ad dignoscendas facilius species liceat omnium hucusque cognitarum conspectum proponere. Sect. I. SEssrtrFLorAE Donn. Sm. et Rose.—Flos arcte sessilis. A. Calycis laciniae inappendiculatae. H. elegans Moc. et Sessé B. Calycis laciniae appendiculatae. 1. Appendiculae 3-4 mm. longae. a. Capsularum valvae dorso carinatae. § H. cornuta Hemsl. b. Capsularum valvae dorso planae. H. microcerata Donn. Sm. et Rose 2. Appendiculae 10-15 mm. longae. a. Calycis laciniae tubo fere aequilongae. H. Rodriguezii Donn. Sm. b. Calycis laciniae tubo multo breviores. 7 Capsula 3.5 cm. longa. H. quercetorum Donn. Sm. et Rose Tt} Capsula 7-8 cm. longa. * Folia ex eepeen ovalia. uacophila Me Sm. et Rose ** Folia ex PUN thes bee aelek H. lemnophila ei Sm. et Rose Sect. Il. PepuncuLataE Donn. Sm. et Rose.—Flos distincte pedunculatus. _A. Pedunculus ovario multo longior. H. Heydeana Donn. Sm. "B. Pedunculus ovario brevior vel ei subaequilongus. . Calycis laciniae inappendiculatae. H. Bércenae Hemsl. . Calycis laciniae appendiculatae. H. Jucida Donn. Sm. et Rose Sicydium (§ Eusicyptum Cogn.) Tuerckheimii Donn. Sm.— Folia maxima oblongo-ovata sensim acuminata supra scabridius- cula subtus pubescentia. Flores masculi in paniculam amplis- simam diffuse ramosissimam foliis reductis bracteatam digesti glabri minimi. Laciniae calycinae cum corollinis bis longioribus lanceolato-ovatae. Filamenta antheris aequilonga. Suffruticosum, caulibus cirrhis paniculis sulcatis et petiolis glandulari- pubescentibus fuscis. Folia coriacea integra pedato-7-nervia transversim venosa 12-16.5 cm. longa 7.5~-10.5 cm. lata, sinu basilari subrectangulari I.5-2.5 cm. lato 1-1. 5 cm. profundo, petiolis 2-3 cm. Fue Cirrhi 8-14 cm. longi apice bifidi. Paniculae, saltem eae florum masculorum, 3-4 dm. longae, ramis divaricatis bractea foliacea 1-3 cm. longa sustentis, tabedioetbias I-1.5 dm. longis, bracteolis lanceolatis petiolatis 1o-14 mm. longis, vel linearibus 2-5 mm. longis, pedicellis plerumque confertis capillaribus 1-2. 5 mm. longis supra medium articulatis, floribus 3 mm.-diametralibus. Calycis tubus incrassatus patelliformis in sicco nigricans. Corollae laciniae 1 mm. longae reticulatae in 50 BOTANICAL GAZETTE [JULY sicco flavicantes. Stamina o.5 mm. longa. Flores feminini fructusque deficiunt. In fruticetis, Cubilquitz, Depart. Alta Verapaz, Guatemala, alt. 350 m., Jul. 1907, H. von Tuerckheim (n. II. 1914). Geophila pleuropoda Donn. Sm.—Tota pilosa. Folia petiolis bis longiora orbiculari-cordata obtusissima. Pedunculi pseudo- axillares folia aequantes vel bis fere superantes, floribus in capitulo subsessilibus quam bracteae involucrantes foliaceae longioribus. Calycis tubus segmentis triente brevior. Corolla calyce altero tanto vel ultra longior. Antherae brevissimae. Caules petioli pedunculi bracteae flores pilis patentibus bulbosis articulatis .5 cm. lon, lateralibus utrinque 5-6, petiolis 1-1. 5 cm. longis, stipulis caducis. ean primum terminales deinde caule producto axillares singuli 3.5-5 cm. lo ngi, capitulo hemisphaerico absque corolla 6-7 mm. alto 5-8-floro, Seaiteis 2 oblongo-ovatis vel o oblongo- lanceolatis in petiolum decurrentibus 6-7 mm longis cito. caducis, pedicellis vix 1 mm. longis, floribus 4—5-meris incite lineari 3 mm. longa sustensis. Calycis tubus 2 mm. longus discum vix superans, segmenta CaN ae 3 mm. longa erecto-patentia, alterna sae minora. Corolla 10-12 mm. longa triente lobata, tubo toto infundibuliformi intus glabro, lobis Seats Sitenas obtusis erecto-patentibus. Filamenta 2mm. longa, antheris oblongo-ellipticis 1 mm. longis semiexsertis. Stylus filiformis, ramis 2 mm. longis inclusis totis ee Drupa ignota. Secus semitam inter Secanquim Sepacuite, Depart. Alta Verapaz, Guatemala, alt. 1220 m., Febr. 1905, se P. Goll Ac al deficiente).— Typus in herbario Musei Nationalis sub numero proprio 860647 servatur. Tabernaemontana (§ EUTABERNAEMONTANA K. Schum.) Deamii Donn. Sm.—Folia elliptico- vel obovato-lanceolata apice contracto- acuminata deorsum attenuata. Thyrsi laterales folia subae- quantes. Calyx inter minimos fere partitus. Corollae tubus cylindraceus gracilis rectus calyce sexies longior lobos proprios subaequans. Antherae sessiles totae fere exsertae. Discus nullus. ‘Stylus elongatus. Folliculi obovoidei cuspidato-acuminati basi acuti. Frutex 3-metralis omnino glaber. Folia pergamentacea nitida 9-12 cm. longa 2.5-4 cm. lata apice ipso obtusiuscula in eodem jugo saepius inaequl- magna, nervis lateralibus utrinque 16-19 sub neha arcuatis et venis te lucem inspectis pellucidis, petiolis 7-12 mm. longi yrsi 10-12 longi, cymulis dichotomis, pedicellis 1o-13 mm. oc Sasi bracteatis. ‘ban 2.5 mm. longus, segmentis paene sejunctis obtuse ovatis basi 4—s-glandulosis. a tort] SMITH—PLANTS FROM CENTRAL AMERICA 51 Corollae in sicco albae tubus 15-16 mm. longus 2 mm.-diametralis faucibus pubescens ore tuberculis 10 munitus, lobi dol oR apice rotundati. Antherae coeruleae 3 mm. longae ultra medium bi tylus 10-12 mm. longus, stigmate 5-apiculato inferne membrana hates Folliculi cuspide 1 cm. longa addita 6.5 cm. longi cartilaginei nitidi pallescentes 4-costati, seminibus ellipsoideis 5—7 mm. longis striatis ad hilum sulcatis, funiculis pul- posis.—Secundum methodum Schumannianam gregi AaaII3** adscribenda. Secus fluvium Montagua prope Gualin, Depart. Zacapa, Guatemala, alt. 190 m., Jun. 1909, Charles C. Deam, n. 6282. Lisianthus quichensis Donn. Sm.—Folia lanceolato-oblonga utrinque subsensim acuteque angustata sessilia amplexicaulia. Cymae longe pedunculatae laxe longeque ramosae. Calycis elongati segmenta ecarinata. Corolla calyce 4-plo fere longior, tubo a basi circiter ad trientem altitudinis sensim angustato et ibidem staminifero subinde infundibuliformi, lobis brevibus erectis. Genitalia exserta. Suffrutex bimetralis glaber, ramis ramulis inflorescentiae axibus teretibus pallido-stramineis, internodiis foli paulo excedentibus, n membrana lineari interpetiolari marginatis. Folia pergamentacea 10-13.5 cm. longa 2.5-3 cm. lata, nervis lateralibus utrinque binis parum manifestis. Cymae pedunculis 5-8 cm. longis computatis 9-17 cm. longae ter quaterve trichotomae, pedicellis 4-7 mm. longis. Calyx ro mm. longus usque ad # partitus, segmentis eeu eater as filiforme attenuatis hyalino-marginatis. Corolla in sicco flavicans 36-38 mm. longa, tubo tertia parte inferiore crebre nervato, lobis dinridise ovate 5 mm. longis. Stamina ad 11-12 mm. supra basin corollae inserta, filamentis inaequilongis 22-26 mm. longis, antheris exsertis oblongis erectis muticis. Discus nullus. Ovarium oblongo-ovoideum 6 mm. longum, stylo stamina 4 breviora aequante, stigmate capitato obscure bilobo. Capsula ignota.—A. L. acuminato Perk. proximo differt praesertim foliis angustioribus, calyce elongato, genitalibus exsertis Rio ; iché, Gusteiadit alt. r100 m., Apr. 1892, Heyde et Lux, n. 2921 ex Pl. Guat. etc. quas ed. Donn. Sm. (Sub Leiantho brevidentato Hemsl. olim distributus.) Lisianthus meianthus Donn. Sm.—Folia oblongo-ovata superne tenuiter deorsum contractius acuminata sessilia amplexicaulia 5-plinervia. Cymae corymbiformes. laxiflorae, floribus minimis. Calycis segmenta leviter carinata. Corollae hypocraterimorphae tubus ultra ovarium tenuis faucibus staminiferis vix dilatatus . calyce atque lobis propriis bis circiter longior. Genitalia exserta. Suffruticosus dense ramosus. Rami teretes cum ramulis et inflorescentiae axibus subquadrangularibus pubverulentes et fusci, internodiis elongatis, nodis linea elevata interpetiolari marginatis. Folia pergamentacea 6-10 cm. lo 52 BOTANICAL GAZETTE [JULY 2.5-3.5 cm. lata, nervis subtus conspicuis longe ascendentibus. Cymae obdeltoideae 7-11 cm. longae repetitus trichotomae, pedicellis vix 1 mm. longis. Calyx 4-5 mm. longus paulo ultra medium fissus, segmentis lanceo- latis hyalino-marginatis. Corollae in sicco luteae tubus 10 mm. longus dimidio superiore tenuiter cylindraceus fibroso-nervatus, lobi oblongo-elliptici 4-5 mm. longi sub anthesi expansi. Stamina ad 2 mm. infra os corollae inserta, fila- mentis aequalibus 3.5 mm. longis, antheris nec recurvis nec apiculatis. Discus nullus. Ovarium calycem subaequans, stylo staminibus aequilongo, stigmate peltato. Capsula oblonga 7 mm. longa reliquiis fibrosis tubi corollae marcidae Sacolal. Depart. Alta Verapaz, Guatemala, alt. 915 m., Jan. 1889, H. von T: ei cininn, n. 1436 ex Pl. Guat. etc. quas ed. Donn. Sm. (Sub Leiantho sapo- narioide Griseb. olim distributus.) Solanum (§ MicrAcANTHA Dun.) purulense Donn. Sm.—Folia bina ternaque integra nitida pilis sparsis stellatis scabriuscula, altero uti alterum paulo minus lanceolato utrinque praesertim superne acute attenuato, tertio 2—-4-plo minore elliptico utrinque acuminato. Racemi laterales stellato-tomentosi, rhachi parce acule- ata, pedicellis flore dimidio brevioribus. — inermis. ami sarmentosi super frutices reclinati lignos retes 5 mm.-crassl aculeati glabri purpurascentes apice cum foliis ee dine stellato-fulvoque- tomentosi, aculeis stramineis e basi compressa 2.5 mm. longa uncinatis 2 mm. longis. Folia dua majora 11-18 cm. longa medio 3.5-6 cm. lata, pilis utrin- 6-8 subtus parce aculeatis, petiolis 1-2 cm. longis dense aculeatis, folio tertio 3-6 cm. longo 1. 5-3 cm. lato breviter petiolato. Racemi 5-6 cm. longi secundi- flori, pedicellis 8-10 mm. longis cernuis. Calyx stellato-tomentosus hemi- i ll 0 mm, rt mm. longa, antheris ie 12-13 mm. longis apice biporosis. Bacca ignota.—Ad SS. lanceaefolium Jacq. accedens. In fruticetis ad Purula, Depart. Baja Verapaz, Guatemala, alt. 1600 m., Apr. 1907, H. von Tuerckheim, n. Il. 1751 Alloplectus metamorphophyllus Donn. Sm.—Folia quam max- ime disparia, altero magno elliptico utrinque acuminato perlonge petiolato, altero nano stipulaeformi lanceolato-lineari coccineo prophylla dua aflora sibi ipso omnino similia fulciente. Corymbus in. axilla folii majoris subsessilis umbelliformis dense congesti- florus, bracteis bracteolis calycis segmentis supra medium subulato- laciniatis coccineis praeter lineam dorsalem glabris. Suffrutex in truncis putridis epiphytalis nodis radicantibus longe repens, caule striato glabrescente erubrescente. Folium in pare majus nascens rgtt] SMITH—PLANTS FROM CENTRAL AMERICA oe. 3 utrinque densissime stramineo-holosericeum, adultum praesertim subtus glabrescens membranaceum mucro-denticulatum 17 22 cm. longum 8-10 cm. latum, petiolo gracili 7-10 cm. longo glabrescente. Folium nanum cum prophyllis paulo altits sitis lateralibus sessile erectum filiforme productum 3-4 cm. longum 6-8 mm. latum membranaceum praeter lineam dorsalem glabrum. Corymbus subglobosus 2. 5-4 cm.-diametralis, pedunculo 6-8 mm. longo et axibus pubescentibus, pedicellis 3-10 mm. longis, bracteis ovalibus vel oblongo- ellipticis 14-16 mm. longis, bracteolis Hany teenie 15-18 mm. longis subulato-productis. Calycis segmenta fere sejuncta aequalia lanceolato- linearia longe subulato-producta 12-16 mm. longa, laciniis 3-5 mm. longis. Corolla nondum satis evoluta pilosa calyce brevior leviter ventricosa basi vix gibbosa ore obliqua, lobis rotundis brevibus. Antherae liberae breves, loculis parallelis distinctis. Disci glandula solitaria cee ovata 2 mm. longa. Ovarium pilosum acuminato-ovoideim 3 mm. longum, stylo 5 mm. longo, stigmate bilobo. Fructus coriaceus glaber Gres wleboed: : mm. longus inde- hiscens, beens funiculo capillari affixis. Flores evoluti ignoti. —Species anormali La me Prov. San José, Costa Rica, alt. 1500-1600 m.: Adolfo Tonduz, Sept. 1896, n. 10884; Aug. 1898, n. 12469: William R. Maxon, Maj. 1906, n. 364. Besleria (§ PARABESLERIA Hanst.) pycnosuzygia Donn. Sm.— Internodia brevissima, Folium alterum altero subduplo majus coriaceum discolor integrum supra glabrum subtus puberulum oblique lanceolatum utrinque acutum, nervis lateralibus validis utrinsecus 5—6 sub angulo angusto longe ascendentibus. Pedicelli aggregati internodio petiolo flore paulo breviores. Corolla calyce subtriplo longior! Ovarium pilosum. Suffrutex, caule simplice tetragono nodis incrassato, internodiis 1. 5-2. 5 cm. longis, partibus novellis canescentibus. Folium in pare majus 10-14 cm. longum 3.5-4.5 cm. latum inaequilaterale, nervis lateralibus subtus — nentibus supra impressis, petiolis -2 cm. longis. Pendunculus nullus, scariosa, postico minore declinato. Corolla coccinea sericea 21-24 mm. longa, tubo recto superne leviter ampliato vix ventricosa basi defracto postice gibbo, lobis rotundatis subaequalibus. Stamina ad 4 mm. supra corollae basin inserta, antheris cohaerentibus transversim ellipticis, loculis orbicularibus. Discus subaequalis 2 mm. altus antice interruptus. Ovarium ovoideum 3 mm. longum, stylo 1.5 cm. longo. Fructus ignotus. In silvis ad La Palma, Prov. San José, Costa Rica, alt. 1459 m., Sept. 1898, Adolfo Tonduz, n. 12545. BALTIMORE, MARYLAND APPARATUS FOR THE STUDY OF COMPARATIVE TRANSPIRATION EDGAR N. TRANSEAU (WITH FIVE FIGURES) The quantitative study of the ecological factors of the habitat naturally leads to a similar investigation of the responses of the “‘growth-forms” to these elements of the habitat. Thus the in- vestigation of the comparative evaporation of various local habitats has led to a complementary study of the comparative rates of transpiration of the plants occurring in them. In this latter work an effort has been made to obtain graphs of the hourly transpira- tion rates under a great variety of conditions of temperature, light, and humidity. For comparative purposes these data are being collected (1) by the synchronous exposure of several plants, and (2) by determining the ratios between the transpiration rate and the rate of evaporation from a standard vaporimeter. It is evident that for conducting a study of this kind, in which data regarding the effects of stimuli and latent periods are essential, the determination of the water losses by the method of weighing at intervals of several hours is, to say the least, unsatisfactory. A very perfect apparatus for the automatic weighing and recording of evaporation rates has been described by GANonc in this journal.” For comparative purposes, however, several of these instruments are required, making the cost beyond the means of at least some laboratories. The following apparatus is essentially a modification of the Ganong transpirograph, developed for the special purpose of comparative work. Its efficiency, combined with its compara- tively small cost, has made it seem worth describing in advance of the discussion of the data which are being obtained by its use. The complete outfit, as shown in fig. 1, consists of a hygro- thermograph, a chronograph, chemical balances, weight droppers, * New precision appliances for use in plant physiology. Bor. GazETTE 39:145. 1905. Botanical Gazette, vol. 52] [54 rg1r] TRANSEAU—APPARATUS FOR TRANSPIRATION 55 and irrigators. Of these the chronograph, the weight droppers, and the irrigators are new forms of well-known devices. THE CHRONOGRAPH.—Where synchronous records are desired, it seemed that a chronograph having several pens to mark on the same sheet of paper would be more desirable than several separate instruments, not only on account of the decreased cost, but also Fic. 1.—Complete apparatus for recording comparative transpiration data: 1, combined hygrograph and thermograph; 2, weight dropper; 6, irrigator; 7, chrono- graph. because the errors of the clocks would be eliminated. The chrono- graph shown in fig. 1 has an eight-day movement attached to a horizontal cylinder 15 cm. long and 15 cm. indiameter. The record is made by pens which mark a continuous line except when drawn aside by an electro-magnet. At present the instrument bears four pens, but it is so constructed that four more may be added on the same side, thus increasing its capacity to eight synchronous records. By lengthening and shortening the hairspring the space traversed by the pen in one hour may be varied from 2 to 5 mm. In the 56 BOTANICAL GAZETTE [yuLy latter case the cylinder makes a complete revolution in about four days. A strip of ordinary millimeter cross-section paper is used for the record sheet. In class experimentation this recording clock has a variety of possible uses aside from this particular experiment. Fic. 2.—Weight dropper and circuit-closing device THE WEIGHT DROPPERS.—As in the Ganong transpirograph, the recording of the water losses depends upon an electrically actuated mechanism which drops a definite weight in the form of a one- fourth-inch ball upon the scale pan whenever the pan reaches a certain height. As shown in fig. 2, the circuit-closing device consists of two platinum points just beneath the delivery tube 1911] TRANSEAU—APPARATUS FOR TRANSPIRATION —_—57 which dip into a small cup of mercury on the scale pan whenever a balance is established. The one gram weights are too heavy to obtain satisfactory records from many of the extreme xerophytes. For these plants I am using hollow brass balls standardized to 0.4 gm. These are not as light as could be desired, but they are better than the gram weights. To be very satisfactory for comparative purposes, the interval between records should not exceed two hours. Where great differences exist between day and night rates, I have used the fractional weights at night and the gram weights during the day. THE IRRIGATORS.—Two points which became evident in the early experiments are that the water content of the soil of the plants to be compared must be essentially the same, and that the water content must be essentially the same throughout the experi- ment. The ordinary method of watering at 24-hour intervals did not give satisfactory results in some instances. In one experi- ment the ratio between two plants Hrs. ¢—-Eietails of the livigator, on successive days was reversed showing on account of differences in soi] nd connections. water content. To avoid errors of this kind the principle of irrigating plants by porous cups suggested by LivincstTon? was brought into use, and the apparatus shown in fig. 3 was constructed. It consists of a slender porous cup similar to those used in my vaporimeters.’ Thisis readily introduced into the soil of a 3-, 4-, or 5-inch pot by removing a core of soil with 2 A method of controlling plant moisture. Plant World 11:39. 1908. 3 A simple vaporimeter. Bot. GAZETTE 49:459. I910. porous cup, water reservoir, 58 BOTANICAL GAZETTE [JULY a cork borer slightly smaller than the porous cup. The cup is connected by glass and rubber tubing to a horizontal reservoir made of a flat-sided “‘specimen bottle.” The reservoir is supported at the side of the scale pan by a light wire bracket, attached to a flat cork upon which the 7890nNMI123456789ONRI1 294 56TE a ee Light aluminum shell containing eo By the plant rests. The second 10 oye ad Se tube at the upper end of the ae = porous cup affords an easy Saturation deficit method of filling the cup. After the water has been — 7 drawn up, this tube is is ehseaae a iA sealed with cement. The i\ air needed to replace the by a capillary tube. By extending this capillary water in the reservoir | tube beneath the water \\ level, the rate at which Vaporimeter 25 enters through the stopper the water is removed may be approximated by the rate at which air bubbles enter. This may yield in- teresting results concerning the relative time of the absorption and _ transpira- » tion maxima. It is 0 Fic. oo for part of the record of Course open to the same experiment 8 objections as the Reinke method of determining the relative rate of photosynthesis in submerged plants. The aluminum shells devised by GANONG! are very satisfactory for inclosing the pots. The 15 cm. shell seems to be the most satis- factory to use, regardless of the size of the pot, because of the larger volume of air inclosed. I have no quantitative data to prove Myriophy llum ro Pelargonium 4 Bot. GAZETTE 41:212. 1906. Jee ee a a ie ate a een te sheer las aaa area) aa re abe ed | SNE eae eh et a en 1g11] TRANSEAU—APPARATUS FOR TRANSPIRATION 59 this, but the plants appear to withstand the experimental conditions perfectly in this largest shell and not so perfectly in the more closely fitting ones. When the irrigators are used, it is convenient to have a 1 cm. hole in the side of the shell closed by a cork through which the air may be changed at intervals by means of a small bellows. This avoids the necessity of removing the roof from the shell during 30 eu Average Ratio 1.08 | See Ratio 137 \ ae | Soto Oe ‘ epee Ee SRE 35 3 a Ne "Average Ratio 133 5 1G. 5. Saeco from the average ratio between two synchronous records cilculated to 2-hour periods: A, two vaporimeters; B, two irrigated pelargoniums; C, two pelargoniums Sead at 24-hour intervals; average ele calculated from the total water losses. the experiment. The smaller pots are brought to the upper level of the shell by being placed on a strip of aluminum bent in the form ofaW. This raising of the pot above the level of the water reser- voir is necessary to prevent flooding of the soil. In constructing the graphs from the actual records and in cal- culating the ratios, an engineer’s slide rule has been found to be a great time saver. Fig. 4 shows the complete record for a portion of experiment 8. To determine to what extent two records may be expected to 60 BOTANICAL GAZETTE [JULY coincide by this method of recording, six experiments of two to five days’ duration have been performed. The graphs shown in fig. 5 exhibit the actual ratios for 2-hour intervals in comparison with the average ratio for the entire experiment, for synchronous records of two vaporimeters (A), two irrigated pelargoniums (B), and two pelargoniums watered at 24-hour intervals (C). These partial records are sufficient to show that variations in the ratios between records must be greater than o.3 in order to be significant. It will be readily seen that the variations in the actual records sufficient to produce this variation in the ratios are very small fractions of a gram in most instances. There are various explana- tions for these minor irregularities: the impossibility of estimating the hourly loss accurately when the gram-interval extends over several hours; shadows made by the framework of the green- house; differences in exposure to light; differences in irritability, etc. Whatever their causes, they must not be overlooked in com- paring plants of different species and different habitats. EASTERN ILLinors STATE NORMAL SCHOOL CHARLESTON, ILL. BRIEFER ARTICLES EDWARD PALMER (WITH PORTRAIT) Dr. EpDwArp PALMER died at his home in Washington, D.C., April 10, 1911, after an illness of a few days. He was an exceptional explorer and collector, who in the field of botany alone is distinguished as the discoverer of 1,162 new species of flowering plants, with many more of his last collecting still remaining to be described. At least 200 plants discovered by him bear his name, and will continue as witnesses to his wonderful activity. He was the son of a pro- fessional florist and_horticul- turist, of Hockwold cum Wilton, in the county of Norfolk, England, where he was born January 12, 1831. Coming to this country at the age of 18 he settled at Cleveland, Ohio, where he formed the acquaintance of Dr, JARED KirTLAND, one of the most eminent scien- tists of his day, and one of the earliest members of the American Academy of Science. From him he learned the art of collecting and preserving objects of natural history, thus laying the foundation of his future career, and through Krrtianp’s influence he was in 1853 appointed naturalist of the “Water Witch,” on her celebrated expedition to Paraguay, which led to our war with that country. After his return to the United States, he was appointed collector in the Geological Survey of California, paying especial attention to the marine invertebrates of the California coast. In 1862, when President Lincoln called for extra troops, he offered his services to his country, and 61] [Botanical Gazette, vol. 52 62 BOTANICAL GAZETTE [JULY after a time was appointed acting assistant surgeon at various posts in the West and Southwest, continuing to serve after the close of the war on frontier stations in the Indian country in Arizona and the Indian Terri- tory. In connection with his work of attending the sick, he familiarized himself with the properties and uses of the medicinal herbs growing in the vicinity of his station, and he occupied his moments of leisure in making collections of animals and plants for the Smithsonian and other institutions. In March 1869 he was sent by the Commissioner of Agriculture on a mission to New Mexico and Arizona, to report on the agricultural resources, commercial products, climate, and fertility of the soil, and the general habitable features of the Southwest. He afterward carried on archaeological investigations in southwestern Utah, and made extensive botanical and zoological investigations in that region, assisted in his work by a circular letter given him by Brigham Younc. The Commissioner of Agriculture, Horace Capron, in his report for 1870, called special attention to the value of his work, and he was congratulated upon his success by such eminent botanists as Professor ASA Gray, Dr. TORREY, and Dr. ENGELMANN, all of whom considered themselves fortunate in having valuable material collected by him. From a scientific point of view, the most important exploration made by him was that of Guadalupe Island, never before visited by a natural- ist. The bearing upon evolution of the remarkable fauna and flora of this island in the Pacific Ocean, off the coast of Lower California, is almost as important as that of the animals and plants of the Galapagos Archi- pelago, as demonstrated by Darwin. Every bird in his collection from Guadalupe, except a single sea bird, proved to be new to science; and. among the plants collected at this time there were 21 new species, the greater part of which have never since been found elsewhere. Other important collections were made by him in southern California and across the border in Lower California. Here, in a great canyon of the Cantillas Mountains, he discovered a plant which proved to be the type of a new genus, named in his honor Palmerella by Professor Gray, who stated that he did so in acknowledgment of Dr. PALMER'S “indefatigable and fruitful explorations of the botany of the south- western frontiers of the United States, from Arizona to the islands of Lower California, in which region he has accomplished more than all his predecessors.” he latter part of Dr. Patmer’s life has been devoted chiefly to exploration in Mexico, and the results have been published chiefly in tort] BRIEFER ARTICLES 63 the Proceedings of the American Academy of Arts and Sciences, and in the publications of the United States National Museum. His collec- tions, both botanical and ethnological, have been remarkable, not for the prettiness of the various objects, but for the completeness of the material and the care shown in his notes. He continued his chosen work to the very end. His last exploration was in rg1o, in the vicinity of Tampico, on the gulf coast of Mexico. After his return he occupied himself in assorting and distributing his _ material. On the occasion of the eightieth anniversary of his birth, the Botanical Society of Washington held a special meeting in his honor, at which a paper on his life and work by the author of the present sketch was read, together with letters written by various eminent men of science not residing in Washington. During the meeting of the society Dr. PALMER was seated in the place of honor, and at the close of the exercises he was presented with an appropriate birthday gift as a token of the appreciation of the members of the society of his important life- work. The venerable traveler received the congratulations of those present with tears streaming down his cheeks, doubtless realizing that this must be his valedictory—W. E. Sarrorp, Department of Agri- culture, Washington, D.C. DEHYDRATING WITH ALCOHOL (WITH FOUR FIGURES) The difficulty which undergraduate students who take courses in histology find in giving regular attention to dehydration, led me to a search for an automatic method. Osmotic means were rejected because they are uncontrollable and give no indication of the stage of the process. Work on the principle of slowly adding alcohol of increasing strength to the tissue developed the simple apparatus shown in fig. 1. During the past two years this apparatus has been used for dehydrating all kinds of plant tissue for histology and embryology. It has also been used instead of glycerin in preparing algae to be mounted in Venetian turpentine. The alcohol from the supply bottle drops from the lower end of the “capillary”? » into the thistle tube, which conveys it to the bottom of the mixing tube B. The alcohol diffuses with the water in B, and the increase in volume is carried to the dehydrating tube C through the connecting tube x. Naturally, as more alcohol is added to B, the strength of the liquid passing into C increases, but as that in B is always 64 BOTANICAL GAZETTE [yuLy only slightly stronger than that in C, the tissues which are placed in C are not injured. In cases where extraordinary care is needed, it may be desirable to keep the tissues some distance from the opening through which the alcohol enters C. The siphon y removes the excess of Fics. 1-3.—Fig. 1, A, supply bottle; B, mixing tube; C dehydrating tube; », waste tube; ¢, ¢, capillary tubes (air vents); u, supply tube; 2, “capillary”; x, overflow; y, siphon; z, tube for starting siphon; fig. 2, “Capillary” on a larger scale: n, large tube; m, smaller tube, aioe to capillary (f) and sealed into Fic. 3 lower end of ; fig. 3, washing jar with gauze neck. dilute alcohol from C. The bent end of the siphon in the waste tube D prevents the automatic emptying of the siphon. When the appara- tus is to be used, tissues and water are placed in C, and an equal volume of water is placed in B. The overflow x and the siphon y, which is filled by withdrawing the air from D through the tube z, are set to keep these volumes constant. The flow of alcohol is started by remov- rg1r] BRIEFER ARTICLES 65 ing the “capillary” and supply tube from the thistle tube and letting them hang downward from the supply bottle for a minute to expel all the air from them. Fic. 4.—Photograph showing supports: to the stem of the double burette clamp, which holds the mixing and dehydrating tubes, is attached a single clamp which holds the waste tube. Mathematical calculations, as well as numerous picnometer tests, show that the percentage of alcohol in C increases very steadily to about 75 per cent. Calling the contents of C one volume, the picnometer tests show that two volumes of 95 per cent alcohol will raise the strength of that in C to 70 per cent, three volumes to 85 per cent, and four to 92 66 BOTANICAL GAZETTE [JULY per cent. However, most tissues may be taken from 85 per cent alco- hol and covered with that remaining in B, and then transferred from that to either 95 per cent or absolute alcohol. The flow of alcohol is insured against varying vapor pressures by the short capillary tubes in the stoppers which close the upper ends of the larger tubes, or if suitable capillary tubing cannot be obtained ordinary glass tubes nearly sealed at both ends will do quite as well. In either case the slightest amount of water in them renders them worthless. The “capillary” is shown at v, and enlarged in fig. 2. It is made by sealing within a larger glass tube a small one first drawn out to a very fine capillary. With a head of 4o or 50 cm. it should allow several drops of alcohol to flow per minute. If the flow is too slow, the small end of the fine capillary may be broken off with a pair of forceps. Otherwise the flow is regulated by raising either the supply bottle or the remainder of the apparatus, which is clamped on the ring stand. As a drop of alcohol from v per minute means r cc. per hour, and most material may be dehydrated in 4o hours or less, it is easy to adjust the flow, and the apparatus needs no further attention until its part of the process is complete. B and C may each conveniently be ordinary glass tubing 15 cm. long and 2.5 cm. in diameter. D is of similar material twice this diameter and 5 cm. longer. It is very convenient to have all three of these tubes graduated. The supply tube should be at least 6 mm. inside diameter, so that, when starting, the alcohol will readily replace the air in it; but, as the contents of the other connections are added to the waste alcohol and dehydration is delayed by the contents of *%, these should not be over 1. 5-2 mm. inside diameter. It seems that only the best antimony rubber tubing will withstand alcohol. Ordinary physicians’ catheters, one large and two small, will furnish all of this tubing that is needed. In practice it is convenient, after killing is complete, to tie the tissue with a label number in a square of fine silk gauze (chiffon). Knots are unnecessary; after the corners of the gauze are brought together a half dozen turns of very fine cotton thread will hold very well. A number of samples may then be washed very effectively under a small tap, in a jar the neck of which is provided with a cylinder of wire gauze as shown in fig. 3. After washing, the samples are transferred to the dehydrator and may afterward be kept in one or at least very few dishes until infiltrated with paraffin. The silk gauze also protects the samples trom the air while they are being transferred to the imbedding dish, where it may be cut and the pieces of tissue and label properly arranged.— W. A. WuLtscniecER, Nebraska Wesleyan University, Lincoln. CURRENT LITERATURE: MINOR NOTICES Die Pflanzenstoffe.—WEHMER' has made readily available the known facts about the plant products (chemicals, drugs, enzymes, etc.) of the phanerogams. The plant families are arranged in the natural order, and under each the genera and species of which we have any chemical knowledge, along with the facts known and citations of literature establishing the facts. On the purely bo- tanical side many facts of distribution are recorded. The work will prove of great value to plant chemists, pharmacists, and plat physiologists. A full index of the chemicals mentioned and a second one of the raw materials and plants greatly enhance the value of the book.—WiL1aAM CROCKER. Micrography of Javanese woods.—The third part of JANSsONIuS’ microg- raphy of the woods of Java has appeared,? and apparently completes this very laborious work, as it contains a general index to the two volumes. e plan of the work was described in the notice of the first part,’ and a notice of the second part indicated the further extension of the work. The present part, beginning in the midst of Meliaceae and closing with Moringeae, con- tains 100 species, the total for the two volumes being 329. Detailed descrip- tions of the vascular elements of so many species, including lists of reagents, sections, and material in each case, and also references to literature under each species, represent an amount and kind of work that few would care to under- ake.— Prodrome de la Flore Corse.s5—Notwithstanding the long series of valuable contributions to systematic botany, both floristic and monographic, by w RIQUET has enriched scientific literature, it is probable that he is chiefly * Weumer, C.. Die Pflanzenstoffe botanisch-systematisch bearbeitet chemische Bestandteile und Zusammensetzung der sR onan Pflanzenarten Rohstoffe und Produkte Phanerogamen. 8vo. pp. xvi+937. : Gustav Fischer. 1911 35 2 Janssonius, H. H., Mikrographie des PMs der auf Java vorkommenden Baumarten; im ‘Aulvoae des genes Ministeriums unter Leitung von Dr. J. W. Mott bearbeitet im Anschluss an “‘Additamenta ad cognitionem florae arboreae javanicae auctoribus S. H. pesos et TH. Uiesta” Dritte Lieferung. 8vo. Vol. II, pp. 161-540. figs. 49. Leiden: E. J. Brill. ro1x. M6. 3 Bor. GAZETTE 43:345. 1907. 4 Ibid. 4°7:416. 1900. S$ BRIQUET, JoHN, Prodrome de la Flore Corse, comprenant les résultats bota- niques de six voyages exécutés en Corse sous les auspices de M. Emite Burnat. Vol. I. Geneva: Georg & Co. 1910. | 67 68 BOTANICAL GAZETTE [JULY known, in America at least, by the devoted attention he has given to the cause of a better international agreement on the controversial subject of nomen- with great self-sacrifice, he brought to bear upon an exceedingly intricate, se coumrinie ng, and unremunerative task. It has been generally known that Briquet for the last ten years or more has been engaged, notwithstanding the serious interruptions to which we have alluded, in an intensive study of the Corsican flora. In order to gain ample oastees and a first-hand familiarity with the floristic conditions, no less than ix expeditions to Corsica were made by him and his associates. Not only were the more accessible parts of the island repeatedly visited, but the wilder portions of the interior, including primitive woodlands, still infested by brig- ands, were traversed and examined. The publication now at hand is the first volume of what has been modestly styled a Prodrome. It is an imperial octavo of something over 650 pages, and contains, besides prefatory matter and bibliography, a critical catalogue of the vascular plants of Corsica from the Hymenophyllaceae to the Lauraceae, including 722 species and many varieties. Under each, the citation of litera- ture, synonymy, and exsiccatae is exhaustive. ere notes and comments on ctive ae racters, distribution, environment, etc., abound, and at points keys are introduced to elucidate distinctions beeen plants of the Cor- sican flora and their nearest relatives found elsewher Without the slightest depreciation of its other oa more scientific merits, national rules of nomenclature by one cated trained in all their shades of meaning and intricate details —B. L. RoBINSON MOTES FOR STUDENTS Genetic studies in Oenothera——The important deductions made by DeVries, from the results of a twenty-years’ study of Oenothera Lamarckiana and its derivatives, have created an unusual interest in this species and its relatives. Numerous investigations have been made by many students, without any apparent exhaustion of the wealth of interesting phenomena presented. The oenotheras seem destined to yield results of great value for a long time to come, for the interest in the group grows greater rather than less with further study. The validity of some of DEVRtiEs’s conclusions rests upon the correctness of the assumption that O. Lamarckiana is a native species. Many diligent searches have been made in the effort to discover it in a natural habitat in America, but so far without success. rg1t] CURRENT LITERATURE 69 Davis® believes that O. Lamarckiana does not occur as a native species, but that it is a hybrid, probably between forms of O. grandiflora and O. biennis, and that it originated in European gardens, or that it may have occurred as a wild hybrid. To test this hypothesis he is making numerous crosses between different forms of these two species, and selecting those types among the hybrid progenies which most closely resemble O. Lamarckiana. He reports that all of the hybrid forms thus far produced by him differ from O. Lamarckiana in several important points, but that the resemblances of some of them to that species are such that the taxonomist would at least place these hybrids next to O. Lamarckiana. Davis is not convinced, by the evidence at hand, that the plants figured in certain old plates or described in various horticultural maga- zines of a century or more ago are to be safely referred to O. Lamarckiana, as they have been by several writers. The effort to synthesize O. Lamarckiana is being continued by the use of other biotypes of the two chosen species, and it is expected that some of these will offer a still closer approach to the desired result. Reports on these further studies will be awaited with the greatest interest, and especially regarding the capacity of any of the new forms to yield a series of true-breeding segregates, such as the forms derived from O. Lamarck- zana which are now generally recognized as mutants. All students of genetics who have handled the oenotheras in hybridization experiments appreciate the fact that they are quite anomalous in their heredi- tary behavior, and that they do not clearly follow the simple procedure usually observed in the hybrids of other plants and of animals. Under the circum- stances, no far-reaching generalizations should be drawn from studies in the oenotheras except on the basis of extensive cultures and the most careful analysis of results. Gates’? has made some features of O. rubrinervis and o a derivative from it, which he calls O. rubricalyx, the basis of generalizations regarding the nature of unit-characters, which appear to the reviewer not to observe this desired caution. O. rubricalyx differs from O. rubrinervis not only in amount of anthocyan in leaves and buds, but also to some extent in its distribution, the latter form having a red hypanthium, red midribs of the sepals, and red on the ventral surface of rosette-leaves and especially of their petioles, in which positions O. rubrinervis has a green or yellowish color. Nine cultures from self-fertilized O. rubricalyx gave in each case not only O. rubri- calyx, but also O. rubrinervis offspring, though the ratios were not satisfactorily determined. The conclusion is reached that therefore O. rubricalyx is inca- pable of breeding true. The number of families is too small, however, to war- rant this conclusion, for Mendelian expectation would allow six of the nine 6 Davis, B. M., Genetic studies on Oenothera. II. Some hybrids of Oenothera biennis ae o grandiflora that resemble O. Lamarckiana. Amer. Nat. 45:193-233- jigs. 18. 7 pe R. R., Studies on the variability and heritability ee eyo in Oenothera. Zeit. f. ad Abstam. Vererb. 4:337-372. pl. 1. figs. 5. 70 BOTANICAL GAZETTE (JULY parents to be heterozygous, and it puts no strain on the “errors of random wired to account Aust the Sopnusauecd three as a purely chance result. Re- s bet O. Lamarckiana seem to have resulted in each case in a progeny of iabeccabes and Lamarckiana, though the deter- minations were defective. The appearance of these two types in the first in the F, and breed true in later generations. This new use of the expression will result in confusion if it is adopted by others, ince all Mendelian inheritance is “alternative,” as the expression is now ists. GATES is of the opinion that O. rubricalyx represents a progressive muta- tion from O. sedanlaet and that it is not to be explained on the basis of the presence and abse ypothesis. For the a le and direct, though some- what formal and — terminology generally used in describing Mendelian behavior, GATES would substitute “ a quantitative readjustment of the rela- tion between the substances which by their chemical interactions produce anthocyan, and those which decompose : as soon as formed, or which, by their presence, divert the metabolic processes and bring about chemical reactions of a different sort.” ile the extent of the anthocyan in O. rubricalyx proved to be strictly uu r riES® has continued his studies on hybridization in the oenotheras, and announces results of unusual theoretical interest, which together with the discovery of “twin hybrids,” earlier reported? by the same author, the reviewer 8 DeVries, H., Ueber doppeltreziproke Bastarde von Oenothera biennis L. und O. muricata L. Biol. Centralbl. 31:97-104. 1911 , On twin hybrids. Bot, GazETTE 44:401-407. 1907. tgtt] CURRENT LITERATURE 7i believes will go far toward solving the anomalous hereditary behavior of the oenotheras. As reported in Die Mutationstheorie (2:471), reciprocal hybrids among the oenotheras are Peer unlike, being usually similar to the type of the pollen parent. To over the significance of this phenomenon the author crossed together the anal hybrids, thus (AX B)F;X(BXA)F,:. The results of such a cross he calls “double reciprocal hybrids.” For the study of these double reciprocal hybrids he has used chiefly O. biennis and O. muricata. It will be seen that there are two possible combinations of the same reciprocal hybrids, e.g. (biennisX muricata) X (muricata X biennis) and (muricataX biennis) X (biennisX muricata). In the first case the cea occupies the middle place in the formula and biennis the extremes, while in second case the position of the two parent species is reversed. The sheers and unexpected result of these crosses is the complete disappearance of the characters of the species occupying the middle position in these formulae. only of biennis, while the alternative arrangement of the parents results in a progeny of pure O. muricata, the biennis having completely disappeared. This remarkable result does not belong only to the biennis-muricata cross, but six other combinations in which O. biennis entered as one of the parental types followed always the same law. These six combinations involved a small- flowering ‘‘O. biennis’’ from Chicago, cruciata, strigosa, Hookeri, Lamarckiana laeta, and Lamarckiana velutina. The same principle holds when one of these F, hybrids is crossed with one of the parental types, e.g. (AX B)F:XA, the result being the same as if the middle parent had not entered into the breeding (in the example the offspring are all pure A). The progeny of such a cross the author calls ‘‘sesquireciprocal hybrids.” From these results it is obvious that the eggs and sperms carry different morphological potentialities. The cross AXB results in an AB heterozygote which produces A eggs and B sperms. The reciprocal cross produces only B eggs and A sperms. DeVries offers the explanation that both A and B eggs and A and B sperms are produced, but that the B eggs and A sperms fail, an assumption which is in accord with the observation that about half the ovules and half the pollen grains are abortive. DeVries has gone further and discovered just what — are carried by each sex. In both pure-bred O. biennis and in its crosses w muricata, the pollen-borne type is epistatic to the seed-borne type, so ace the latter is never seen; but in a series of crosses of O. biennis with “ biennis Chi- cago,” cruciata, Fisclen. strigosa, and Lamarckiana, the seed-borne type of O. biennis is epistatic to the pollen-borne type of the other species, thus allow- ing it to become visible. The F, offspring between biennis S and all these other species resemble O. biennis, which therefore represents the pollen-borne type. The F, between diennis 2 and all of the species mentioned gives a new form unlike biennis and unlike any of the pollen parents, but essentially identical in all the crosses. This new form is the seed-borne type of O. biennis. 72 BOTANICAL GAZETTE [JULY The author calls it the “conica-type,”’ because of its characteristic thick conical buds. It has been Soenibed already as “‘velutina’’ in the same author’s papers on “twin hybrids.’”” While O. muricata was incapable of such com- plete analysis as was given to biennis, owing to the fact that many of its hybrids are weak or sterile, several crosses in which muricata was used as the seed parent show that in this species also there is a morphological type determined by the egg cell different from that carried by the pollen cell. The seed-borne type of O. muricata is called by DEVRiEs the “‘frigida-type.”’ It comes to light in crosses of O. muricata as seed-parent with “ biennis Chicago,” Hookert, and strigosa pollen parents. It has tall, ates nearly glabrous stems, but little branched, with flowers resembling O. bien ese results are of unusual theoretical Gas and the study of double reciprocal hybrids will no doubt lead to the — of other instances in which different potentialities are borne by eggs and sp HonInc” has made a statistical study of the “twin hybrids” of O. Lamarck- iana and O, rubrinervis in the attempt to identify the velutina with rubrinervis and Jaeta with Lamarckiana. He finds in nearly all the morphological char- acteristics which differentiate the twin hybrids a fairly close parallel with the convinced by these facts that O. Lamarckiana and O. rubrinervis are both of hybrid nature, each possessing in the latent state the characters of the other. He offers no suggestion, however, as to how it happens that this hybrid nature fails to ca itself when O. Lamarckiana and O. rubrinervis are self-fertilized. ZEIJLSTRA™ has discovered that the most common form of O. nanella is er , a Micrococcus which forms zoogloea-like masses in the cavities of the cells. The diseased plants have a characteristic appearance which em easily detected even in their early stages. Normal (that is, undiseased) O. nanella has also been discovered, but much more rarely, and the latter has never fruited. It is suggested that the true normal O. nanella may have been frequently overlooked, owing to its resemblance to O. Lamarckiana. How it happens that all the offspring of the diseased O. nanella are of the parental t needs investigation. The author points out two alternative explanations: namely, that this diseased strain of O. nanella inherits a suscepti- ility to the attack of the Micrococcus, or that the germ cells are themselves infected by the parasite. In the latter case a microscopic study of the germ cells should perhaps detect the presence of the Micrococcus.—Gro. H. SHULL. 10 HONING, J. A., Die 2 amen der Oenothera Lamarckiana. Zeit. f. Ind. Abstam. Vauk 4: ‘ik Sigs. 10. 1911 ZEIJLSTRA, H. H., Oenothera nanella DeVries, eine krankhafte Pflanzenart. Biol. Centralbl. 31:129-138. figs. 5. 1911. Toit] CURRENT LITERATURE 73 The determination of sex.—In a recent paper on the determination of sex, STRASBURGER” adds to his already extensive contributions to this difficult subject. As in previous papers, he maintains that the problem is phylogenetic, and that there is a striking parallelism between the animal and plant kingdoms in the evolution of sex. In both kingdoms the original differentiation appears only in the haploid generation, but with the differentiation of sex in this genera- tion came fertilization and the formation of a diploid generation, which, in both animals and plants, became the dominant one. The point at which the separation of sexes takes place | in various plant groups is noted briefly; the statements, in most cases, depending upon facts already known, rather than upon cytological or other evidence in connection with this particular paper. In monoecious Chlorophyceae the thallus is bisexual and the sexes are separated at the formation of oogonia and antheridia; at fertilization the two sexes are united; the reduction of chromosomes takes place during the first two divisions of the zygote, but is not accompanied by any separation of sexes, the product of the zygote being bisexual. In dioecious Chlorophyceae the separation of sexes occurs at the reduction division, so that the products of | the zygote are unisexual. Thus the separation of sex tendencies appeared first in connection with the reduction divisions. In monoecious bryophytes there is no separation of sexes at the reduction divisions, the separation occurring later, at the formation of antheridia and archegonia; but in dioecious forms the separation occurs at the reduction division. That the separation of sex tendencies as well as their union at ferti- lization is decisive, is shown by the fact that protonema from vegetative cells of a sporophyte of a dioecious moss produces leafy plants bearing both anther- idia and archegoni In hcmngiiaaae pteridophytes there is no separation of sexes at the reduc- tion divisions, the spores being bisexual and the sex tendencies being separated later in the gametophytes arising from the spores. The division which many homosporous pteridophytes show in their gametophytes is due merely to external factors, the gametophytes being really monoecious. In heterosporous forms the separation of sexes does not occur at the reduction divisions, but much earlier, during the divisions leading to the formation of spore mother cells, so that the spore mother cells are already all male or all female, all the spores of a microsporangium producing male prothallia and all those of a megaspo- rangium producing female prothallia. The two sex tendencies are united in the sporophyte, which can then produce both microsporangia and megasporangia. Through the heterospory of the sporophyte the dioecism of the gametophyte became firmly established. In seed plants the sexes are recognized by the external ‘‘sex organs” of ™ STRASBURGER, EDUARD, Ueber geschlechtbestimmende Ursachen. Jahrb. Wiss. Bot. 48:427-520. pls. 9, 10. 1910 74 _ BOTANICAL GAZETTE [JULY the diploid sporophyte. In heterosporous plants there is no sex differentia- tion except that which leads to the formation of microspores and megaspores, for from a microspore mother cell come four spores which produce only male products, and from a megaspore mother cell come four spores which produce only female products. If all sporophytes were bisexual, the problem would be comparatively simple, but there are sporophytes which produce only micro- sporangia or only megasporangia, and these dioecious seed plants, although their number is comparatively small, have been used extensively in the study of sex problems. A large amount of experimental work is recorded, the principal forms used being Mercurialis annua, Melandrium rubrum, and Elodea canadensis. In Mercurialis annua ovulate plants sometimes bear occasional staminate flowers, and similarly, Seshices plants sometimes bear occasional ovulate flowers. STRASBURGER had already found that the flowers of an ovulate S flowers on a staminate plant, when pollinated from the same plant, bear seeds which produce only staminate plants. Some plants have ovulate flowers with staminate flowers growing up through them in a sort of proliferation. Pol- lination of such ovulate flowers with pollen of the proliferating flowers gives rise to seeds which produce both ovulate and staminate plants. The con- clusion is that in the scattered staminate flowers the male tendency has become weakened, and that in the scattered ovulate flowers, the female tendency has become weakene In the Rinectons Melandrium rubrum, pollination was effected by pollinat- ing with thin transverse sections of still unopened anthers. It was hoped that grains with the stronger and with the weaker male tendencies. In all, 1475 seeds were secured, and from these there were obtained 1124 seedlings, 1035 of which reached the flowering stage. Of these 376 were staminate and 659 ovulate, the ovulate being strongly dominant. * The work on Elodea canadensis is interesting, but is still in an unfinished condition. Although ovulate plants have long been abundant in Europe, staminate plants are not available. Staminate plants and seeds were secured from Wolf Lake, near Chicago, and hundreds of stigmas were pollinated, each with a single pollen tetrad. Fertilization has taken place, but seeds are not yet ripe. If each ovary should produce four seeds, two of which should pro- duce staminate plants and two ovulate plants, there would be some definite dat The general conclusion from the data, only a small part of which has been indicated here, is that all eggs are female and all pollen male, but that some pollen has a strong and some a weak male tendency. Pollen with a strong male tendency overcomes the female tendency of the egg, while pollen with the weak male tendency is overcome by the stronger female tendency of the egg. The Se tort] CURRENT LITERATURE 75 fact that eggs of apogamous forms may produce staminate as well as ovulate plants does not affect the problem, since such eggs are diploid, and the sex tendencies have not yet been separated. The case is similar to that of budding. A cytological study was made in Melandrium rubrum, Cannabis sativa, and Mercurialis annua, but at present no cytological features have been recognized which seem to have any bearing upon the problem of the separation of the sexes. In Melandrium rubrum one chromosome is constantly larger than the others, as was noted during the reduction divisions and in vegetative cells, but it could not be connected with sex differentiation. The problem is unusually large and difficult, and the present paper suggests many points of attack.—CHARLES J. CHAMBERLAIN. Crown gall.—The most noteworthy contribution recently made to plant pathology is the bulletin on crown gall of plants by Smiru, Brown, and Town- SEND.%3 This disease, on account of its wide distribution and the conspicuous nature of the deformations to which it owes its name, has long attracted the attention both of practical horticulturists and plant pathologists. Yet, with the exception of the work of some Italian investigators, little has been done to work out the etiology of the disease. From general observations it has been believed that the disease is communicable, and one investigator (CAVARA isolated an organism from a gall of the European grape and established a strong probability that it was the causal organism of that particular gall. The nature of the outgrowths known as crown gall and occurring on a great many different kinds of plants, the cause of their occurrence, and the relation of the crown galls of different plants to each other, have remained among the most obscure problems in the whole field of plant pathology. The results of investigations on these problems are reported in the present bulletin e work begins with a short historical sketch of the more feito investigations on the crown gall, special emphasis being laid on the work of Italian investigators who first ascribed the disease to bacteria. This is followed by an account of the isolation of the causal organism, and the evidence showing that the crown gall of various plants is due to bacterial organisms; and that these belong either to a single species or to closely related species or strains, each of which can be inoculated into many species of plants. The morphology crown gall and some animal tumors is discussed. is similarity is emphasized by the occurrence of metastases in infected plants. The last part of the bulletin relates to the practical aspects of the subject, together with a statement of the plants infected and their distribution. The evidence given in the first part is supported by 36 excellent plates. 3 Suit, E. F., Brown, NELLIE A., TownsEnD, C. O., Crown gall of plants; its cause and remedy. Bur. Pl. Ind. Bull. 213: pp. 200. pis. 36. figs. 3. 1911. 76 BOTANICAL GAZETTE [JULY It may be said that the beginning of the present work dates back to the discovery of gall-like outgrowths on the stems of the Paris daisy (Chrysan- themum frutescens) in 1904. It was not until 1906, after many unsuccessful trials, that an organism was isolated which when inoculated into sound plants caused the growth of galls similar to the ones from which the organism had been obtained. The organism was inoculated from pure cultures into many different plants, several hundred inoculations having been made. The results showed that on nearly all herbaceous plants tried, such as daisy, pyrethrum, tobacco, clover, cotton, sugar beet, hop, and others, galls were produced as a result of the inoculations. Inoculations into such woody plants as rose, grape, almond, poplar, and Persian walnut also gave galls, but with less frequency than the herbaceous plants. JInoculations on a number of other plants did not result in the formation of galls, although in some instances inoculations had been successful in other experiments with the same plants. Later, crown gall organisms were isolated from a large number of other plants, th woody and herbaceous, including the common nursery trees, as apple, peach, and poplar, which suffer most seriously from the crown gall, and such organisms were also capable of infecting a number of hosts besides the original one. The “hairy root” of apple, which has been more or less associated with crown gall in the minds of nurserymen, was found to be due to the same organism which when inoculated into other plants, as the sugar beet, for instance, gave galls with the characteristic hairy roots. The vast amount of evidence of this nature presented in the bulletin shows that the crown gall and similar tumors, and the hairy root disease of various plants, are due to bacteria, and that the organism of each kind of plant is capable of being inoculated at least into several other plants. The organisms from different sources, while similar in their general characteristics, show minor cultural differences. This behavior leads the authors to leave undecided the question whether the organisms constitute several species or a single species with several races. An interesting comparison is made between the crown gall outgrowths and animal tumors to which they show resemblance in growth and organization. This resemblance is carried still farther by the formation by the plant galls of metastases, which occur at some distance from the primary gall, but without the intervention of new infections. It is suggested that the metastases occur as a result of growths from the primary galls. Another important idea is brought out in a number of experiments which tend to show that plants acquire immunity to the crown gall organism as 4 result of repeated inoculation. If the result of those experiments should be confirmed by future work, this would be the first instance of immunity in plants analogous to that in animals. This work has removed from the domain of speculation the cause of crown gall and kindred diseases affecting many plants. These diseases, in all their varied manifestations, are shown to be due to a common cause. The enormous rort] CURRENT LITERATURE 77 amount of evidence presented leaves no doubt as to the correctness of the conclusions. Aside from having solved one of the most obscure problems of plant pathology, the authors have shown that it has a more general bearing in showing that these plant galls, due to bacteria, present many analogies to animal tumors. The successful isolation of causal bacteria from the plant tumors, after many failures, leads one to hope that the work will stimulate renewed search for organisms in animal tumors.—H. HASsELBRING. Coastal floras —H. CHERMEZON™ has recently made a contribution to the study of coastal floras. In the introduction he calls attention to the well known peculiarity of these floras, the interest they have excited in botanists since ancient times, and the theories advanced as to the relation between them and salt in the soil. The main part of the work is divided into three sections. In part 1 is given a description of the structure of the leaf and stem of a large number of plants of the coast, chiefly of France, but also of some of the salt-desert regions of Tunis. In part 2 a study is made of the characters peculiar to plants of the coast. There are three categories of habitat: (1) the region of sands, including (a) beaches and (6) dunes; (2) region of rocks and cliffs, including (@) rocks and bowlders exposed to the spray and (0) the top of cliffs; (3) damp salty places including (a2) muddy flats and salt marshes (the halo- phytic zone par excellence), and (6) damp prairies, not reached by the sea, which form a transition to the flora of the interior. Part 3 is devoted to a discussion of the flora. It is divided into two parts: (x) marshes, rocks, and beaches; and (2) dunes and sands. The transition between the two is made by the plants of the beaches which have characters common to both. In the first group succulency and development of water- tissues are the striking features, while the second shows more often thickening of the cuticle, sinking of stomata, and abundance of hairs. As the stations of the first group are the most salty, while the dunes are not salty at all, the author distinguishes two sorts of floras, the halophilous and the xerophilous. The xerophilous flora reaches its maximum in the dunes, where the characters are such as are met with in other xerophilous floras; but it is less specialized than that of the desert or even the Mediterranean flora, since the dryness is less pronounced and less continuous. The halophilous flora occupies the beaches, the rocks and bowlders, and the salt marshes. The beach and the dunes are not distinct, plants passing from one to the other; but a great many sand-loving plants of the dunes are absent from the beach, which the author explains by the presence of salt, small in amount but sufficient to eliminate them. The rocks and bowlders in the vicinity of the sea, exposed to the spray, are occupied by a flora with special characters, less halophilous than those of “4 CHERMEZON, H., Recherches — sur les aie littorales. Ann. Sci. Nat. Bot. 12:117-313. figs. 52. 19 78 BOTANICAL GAZETTE [JULY the beach flora. In the salt marshes is found the most halophytic flora. Several plants have hygrophilous characters, as canals or lacunae. n conclusion, the coastal flora is composed of xerophilous and halophi- lous members, showing points of contact; plants of the xerophilous flora ave moderately xerophilous characters, ag as epidermal protections slightly de eloped plants of the halophilous flora exhibit succulency of leaves and of stem and water-tissues; characters in common to the two are isolaterality of oe and compact structure of the mesoph IL. he author objects to ScuimpEr’s placing halophytes among xerophytes and says: “‘The cape iasiagitl results from confusion. between the two different ities. The fact that there are succulent plants outside the coast simply proves that succulency may be related to other factors of the soil besides salt, but its frequency in plants of salty earths shows that there exists a certain relation fy the toxic action of salt, or that the appearance of succulent plants on the coast is due to lack of competition there, he thinks insufficient, and concludes that a flora as special as that of the salt marsh should be considered as halophilous in the proper sense of the word. The author admits that succulency may be due to other factors than salt in the soil, but does not make it clear why he objects to considering that “physiologically dry” soil and really dry soil may occasion the same structure. ScHIMPER’s argument seems to us to stand. —A. M. STARR. Inheritance of flower-form and color in Digitalis—A familiar garden variety of Digitalis has the central axis terminated by a peloric flower. KEEBLE, PELLEw, and Jones* find that this form is a Mendelian recessive to the typical form, and that, as might be expected, the inheritance is the same whether the seeds are taken from the peloric flower or the normal zygomorphic flowers of the same plant. The flower-color is referred to three pairs of allelo- morphs: Mm, a magenta factor; Dd, a darkener which changes the magenta to purple; and Ww, a dominant white factor which removes the effect of M except in the small spots which occur on the corollas of all Digitalis. When M is present these spots are red, and when absent they are yellow. Miss SAUNDERS" has studied the inheritance of an interesting form of 5s KeEBLE, F., Perrew, Miss C., and Jones, W. N., The inheritance of peloria and Riacaie' in foxglove (Digitalis purpurea). New Piveslogiat 9:68-77. fig. I. — UNDERS, Miss E. R., On inheritance of a mutation in the common foxglove Pate purpurea). New Piytobosiet 10:47-63. pl. 1. figs. 12. 191 ro1t] CURRENT LITERATURE 79 Digitalis which has been noted occasionally for nearly a century, and which was described by CHAMisso in 1826 under the name D. purpurea heptandra. The characteristic features of this form consist of a dialysis of the corolla and staminody of three or more of the petals, thus producing flowers having most typically 7-9 stamens, and scarcely to be recognized as a Digitalis flower at all. The degree of development of these characters is variable, and somewhat influenced by the environment, but there is no real transition to the normal . This form proves to be like the peloric variety, a Mendelian recessive to the normal. The reviewer has also been studying the inheritance of this peculiar variety for five years, and has reached the same conclusion. Miss SAUNDERS confirms the results of KEEBLE, PELLEw, and JoNEs as to the color- characters.—GEo. H. SHULL. Water relations of desert plants——FitTtInc"’ has studied the water rela- tions of the plants growing on the Sahara. He finds, as Livincston found for the Arizona desert, that the water is generally gained from the surface layers of the soil and not by deep rooting. Many of the plants, especially the perennial shrubs not provided with water-storage organs, develop remark- ably high osmotic aay which enables them to withdraw water from the ee dry soil. On the other hand, the annuals showed much lower motic pressure, with lack of ability to thrive in the most exposed places. In many cases the high pressures were due largely to stored NaCl, but fre- quently entirely to other solutes. the 46 species studied, 21 per cent showed an osmotic pressure exceeding 100 atmospheres; 35 per cent exceeded 53 atmospheres; 52 per cent, 37 atmospheres; while only 11 per cent showed osmotic pressures as low as 11 to 22 atmospheres. Species showing extremely high pressures in dry desert conditions show much lower pressures in moist situations. This marked power of certain plants to adjust their osmotic pressures to the water-withholding power of the medium in which they grow has been demonstrated for salt marsh plants by H1L1," a piece of work which Firtinc does not cite. We have known little about the osmotic pressure of desert forms, and this work supplies much of the deficiency and makes rr character of great significance in the physiology of these forms.—WILL OCKER. Permeability.—SCHROEDER”® has studied the semipermeable membrane of the wheat grain, and confirms the work of Brown on the barley, but adds little that is new. The portion of the coat forming the semipermeable mem- 7 Firtinc, Hans, Die Wasserversorgung und die osmotischen Druckverhiltnisse der Wiistenpflanzen. Zeitsch. Bot. 3: 209-275. 1911. Hirt, F. G., New Phytologist 7:133-142. 1908; Rev. in Bot. GAzETTE 472170. 1909. *9 SCHROEDER, H., Ueber die selektiv permeable Hiille des Weizenkornes. Flora 102:186-208. Ig11 80 BOTANICAL GAZETTE brane originates either from the inner integument or from the nucellus. shown that water and the solutes capable of entering do so mainly through the if alcohol is added to its water solution. Ether renders the coat more readily permeable to water, while treatment with osmic acid renders it less so. While this membrane, being of the non-protoplasmic type, is of great theoretical interest, it has not been demonstrated of any biological significance to the seed itself. In these cultivated forms it is probable that, if such a significance existed, it has been eliminated by selection. A study of this membrane in wild grasses might prove of interest. Many of the wild forms show delayed germi- nation, and in one at least, wild oats, rupturing the coat overcomes the delay.— WILLIAM CROCKER. Leaf-fall—The phenomena accompanying the process of defoliation have been investigated by LEE” in nearly 50 species of trees and woody plants. e separation layer is formed from existing cells, with or without division, and cuts off the leaf by the degeneration and disappearance of the middle lamellae of the cells involved. The vascular elements are ruptured, but usually only after tyloses have filled them. The character of the invariably present protective layer is made the basis of classification, and the species studied are segregated according to whether the ligno-suberized protective cells arise (x) without further modification from existing cells; (2) after irregular division of existing cells; or (3) from a regularly active cambium. Whether the ligno- suberization comes before or after defoliation leads to subdivisions of the first two classes. The production of a cork layer continuous with the periderm of the stem usually follows in the growing season succeeding defoliation.— Gro, D. FULLER. » LEE, E., The morphology of leaf-fall. Annals of Botany 25:51—106. I9II. a | i ? THE BoTANICAL GAZETTE August IQIr Editor: JOHN M. COULTER 7 CONTENTS The Adult Cycad Trunk Charles J. Chamberlain A Botanical Survey of the Huron River oe George Plumer Burns The Vegetation of Cranberry Island (Ohio) — Alfred Dachnowski Briefer Articles Is Ophioglossum FREEE Anomalous? Chrysler Cryptomeria japoni Ansel = shobes Current Literature The University of Chicago Press CHICAGO, ILLINOIS THE CAMBRIDGE UNIVERSITY pki Re and Edinburgh - ee WILLIAM ene & SON, London tes TH. STAUFFER, Leipzig he THE MARUZEN- KABUSHIKL KAISHA. Tokyo, ‘ime Keote. ‘acu ay BIOLOGICAL SCIENCES] BOTANY Morphology of Remit ga By Joun M COULTER HARLES HAMBERLAIN. 47° pp. 2. ie S atladerations, 8yvo, cloth; post- paid, $4. epee e ee Bee By gees ES = RLAIN, edition. x-+-26 slit 8vo, ed et $2.25; poste $2.39. eae in creo By CHARLES J, CHAMBER- h three iikoeeaphic plates. 18 pp., ie, Sheen net, 50 cents; postpaid, 53 cents. The Ecological Relations of the Vegetation oF the = - deme é of Lake Michigan HEN s. rh 2 EM paper ; net, 4 sates yaaa re cen se cea in Saprolegni By BrapD AVIS. With beroHeinogeanbie plates. ar. PP., a paper; net, 75 cents; postpaid, 79 cents, ez a, iat of Angiosperms. By JoHN M. LTER. 6 pp,, 4to, paper; net, 25 cents; Ra ress 27 cents. The Life History of Polysiphonia Violacea. By SHIGEO YAMANOUCHI.. 54 pp., 10 plates, vo, paper; net, $1.00; postpaid, $1.05. ZOOLOGY Animal mrp iors picnics perce’ in Micro- CHA UYER. one oe ages ~ asteatons, ava, cloth; net, $1.75; postpaid, $1. The Development of phe and Color Patterns of Coleoptera, with Observati ma on the alee yg of Colors in Other ers of Ins Bie With three paeta§ erie plates. 40 pp., 0, paper; net, $1.00; postpaid, $1.04. imal Ecology of i Cold Spring Sand Spit, with Remarks on the Theory of —. tation. By Cuartes B. DAVENPORT. 22 pp., 4to, paper; het, §0 cents; postpaid, 53 San Laboratory Outlines for the Study of the Em- bryology of Chick and the Pig. By FRANK R; LILLE. 43 PP» paper; net, 25 cents; postpaid, 27 cents BACTERIOLOGY The Self-Purification = hears: O, JORDAN. ith two maps. 12 pp., 4to, paper; net, 25 cents; : poltpnid: is cents, iss EDWIN PHYSIOLOGY poke = oo Physiology. By Jac LOE two parts. 806 pp., 8vo, cloth, net, $7. Pe postpaid, $7.91. tb inet Marae A as the Pere = Pe 6 pp., illustrated, 8vo, cloth; net, $1.50; postpaid $I. Lucid, terse, — "Knowledge and Scten- tif aves (Lendon). e volume is an unusually elegant one, which makes Suvonenat of yophadicin yy cbt Society Worl This is: an extremely readable book. + Technical ae bersetzung ist ausgezeichnet.”’—Zertschrift fur physttaliocks Chemte. NEUROLOGY ee wae Technique. By Irvine Har- ii-++ 184 pp., 8vo, cloth; net, $1.75; postpaid, er me ae ee ot = any other book of its size that seems mplete — seful.”—Journal of Amertcan Medical Assoctatis saw = ie of no similar book which will = as valanbie 1s the sake of “neurological technique. American ss ho alofinsa “CAs tuccinct, but suffic say comprehensive intro- sete and labor “ guide to the subject, the book may warmly recommended.” —8ritish Medical Yournal. The Finer Structure of the Neurones in the Nervous System of the White By With four colored plate $. SHINKISHI HATAI. ; postpaid, 14 ae ee paper; net, 75 cents 78 ce ANATOMY A ae et of the Brains and — Cords Hereditary amily De- . Sanger Brown. By LEWELLYS With wee Sgn tats plates and eee ee net, $2.00; postpaid, B; “The arti mely sting to neurologists and medical men, Tt oes: a profound insight and knowledge of ee! hareerss treated,” —A nowledge. gether it is an el abarail and. well-executed essay The Distribution of Blood-Vessels in the Labyrinth o ticus.. By Grorcr E. SHaMsB eight colored alate 20 pp., 4to, paper: meh $1.25; postpaid, $1.29. é Seem gre of the Glands of Brunner By SLEY. . With five plates. “$0 ee es paper; st $1.00; postpaid, $1.95 aaa ee THE UNIVERSITY OF CHICAGO PRESS] Address Dept. P. CHICAGO, ILLINOIS — Se nel The Botanical Gazette _ A Monthly Journal Embracing all Departments of Botanical Science Edited by JoHN M. CouLTER, with the assistance of ser members of the botanical staff of the University of Chic Issued August 18, $943 Vol. LIL CONTENTS FOR AUGUST 1911 No. 2 — THE ADULT CYCAD TRUNK. See FROM THE HULL BOTANICAL LABORATORY 146 (WITH TWENTY FIGURES). les J. Chamberlain 81 A BOTANICAL SURVEY OF THE HURON RIVER VALLEY. VII. EDAPHIC CONDI- TIONS IN PEAT BoGs OF SOUTHERN MICHIGAN ida ITH EIGHT sda at George Plumer hates e . : 105 THE VEGETATION OF CRANBERRY: ISLAND (OHIO) AND ITS RELATIONS TO THE SUBTRATUM, TEMPERATURE, AND EVAPORATION II a5 TH ONE FIGURE). Alfred Dachnowshi oe - 126 | BRIEFER ARTICLES ‘ Is HIOGLOSSUM PALMATUM ANOMALOUS? J/. A. Chrysler - - - - aes > se PTOMERIA JAPONICA (WITH FOUR FIGURES). Ansel F. pious 3 - mete mck Ee ey va eae TORE , . = . * ne My g aoe 4 Oa o rel (7) = aA o # ie = re] 25 a oe i=) aa i] wy - ry @ ne eae ao or the Continent ae bata ge Th, Stauffer, Universitatsstrasse 26, Leipzig, > ipoeeai Yearly sub- riptions, sony ane e, M. 33 each; single c opies, inclu og g postage, M. 3. F aru onapigraecanegs Reset 0 16 6 Nihonbashi Tort ‘Sanchome, a Claims for missing numbers should be made within the pene followi ving ne og dase: month on publi- n los The publishers expect to supply missing numbers free only when they h ransit, Business correspondence should be addressed to The University of Chi icago gees Chi Tl unications for the editor should be aa Noga to ae he Un versity of Ch ieee, 6 Chicaes: iil. Contributors are requested to write scientific aud proper with particular care, to ystem of weights and measures, ne in poser ‘ “follow the form, pial in the pages of the BOTANICAL — 2 . rs in excess of ee -two printed pages are not o> unless the author is willing to pay the dditional pages, in which case the number of pages in the volume is correspondin sai creased, ions are barapthed without cost to author only oie suitable — are supplied. A copy the Suggestions made in the January number, 1907, will be sen = application. It is advisable to : : nS ‘ ks a. Leah di les without covers will be supplied gratis. A table showing appro: Siecle cost of ese er rinted on an order blank which accompanies the proof; a copy will be sent on reque ar Entered August 21, 1896, at the Post-Office at Chicago, -cond- class matter, under Act of Cong! / 3y 18 parates, if desired, must be ordered in advance of publication. Twenty-five separates of crigittal = ITALIAN BOOKS very descriptio ITALIAN ‘BOOK COMPANY 520 BRO WAY SUCCESSOR TO FRANCESCO TOCCI EW YORK rks of: Barrili, Butti, Caccianiga, Capra Wo nica, Capua ana, Cardue ci, Castelnuovo, Cor- Nee Negri Praga, — Serao pen gs jorsi faaaitig writers, always on hand Catalogue mailed on nega RANCH 147 MULBE Morphology of Gymnosperms By Joun M. CouLTER AND CHARLES J, CHAMBERLAIN mi-quarterly, with illustrations. Subscr The Journal 0 Geology CHICAGO, ILLINOIS ro ted by Thomas C, Chamberlin. Goecate ine price, $3.00 a year; single copies, a THE ASTROPHYSICAL JOURNAL Issued monthly except February and August. $5.00a year; single copies, 65 cents, Foreign postage, 62 cents. Che Unibersity of Chicago press HICAGO, ILLINOIS "pe tae of eeke! aera, “= bro reanized | N 1901, Coulter and Chamberlain published their “ = its place as the sta icudard your on the. subject. 4 3. Bald Th ii1e im Mense 4 * ig 2 3 } revision of the book. This is now Presented to the evolutionary tendency. but for advanced students in the morphology © gymnosperms 470 pages, 462 illustratio ,8v0, cloth. Postpaid $4.22 The University of Chicago Press Chicago - - - Illinois A Laboratory Guide in Bacteriology By PAUL G. HEINEMANN Second Edition, Enlarged and Revised The Guide is confidently offered in the belief that it will commend itself, even more s for advanced work in the various branches of bacteriology. 216 PAGES, 12MO, CLOTH POSTPAID - «+: = $1.50 The University of Chicago Press Chicago, Illinois Contributions to Medical Science By Howard Taylor Ricketts sexgeoe’ Jn Tribute Be = Memory by His s under t. pices of the set 0 pie neo ney Sasa R. RICKETTS died of oo fever i ia on Ci M untain n spotted fever, give Dr. Ricketts a high ney honorable place on the records of medical future investigators. a is al im ressive memorial to a man wh se life was "delat laid down in the service ‘of yhaaian ee 508 pp., 8vo cloth; net $5.00, domestic postage 33° SEASON aaa The University of Chicago Press Chicago Tilinoss VOLUME LII .- : NUMBER 2 eRe 3 BOTANICAL = AgELIE AUGUST rgri THE ADULT CYCAD TRUNK CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 146 CHARLES J. CHAMBERLAIN (WITH TWENTY FIGURES) The structure and development of the cycad seedling is fairly well known in all the genera, and in Dioon, Ceratozamia, and Microcycas recent investigations have been particularly thorough; but some features of the adult trunk have hitherto escaped observa- tion, doubtless because such material is so difficult to obtain. Asa matter of fact, most of the descriptions are based upon dead con- servatory plants which had begun to decay and so had become worthless as ornamental specimens. Historical As early as 1829, BRONGNIART (1) described the stem of Cycas revoluta, and showed clearly that, in spite of the external habit, the woody structure was not at all related to that of palms, but resembled the wood of dicotyls, the principal difference being that Cycas had no bast or growth rings. Von Mout (2) studied a specimen of “Zamia latifolia” (En- cephalartos) 1.5 meters in height, and also a section of a large trunk of Cycas revoluta. He recognized the bast and described the histological characters of the wood, which he found to resemble that of dicotyls, except that it lacked true vessels. In the pith he found bundles like those of many cacti. There were no growth rings. 81 82 BOTANICAL GAZETTE [AUGUST The excellent work of METTENTUs (3), published in 1861, deals with Cycas revoluta, Encephalartos horridus, Dioon edule, and Zamia muricata. The course and structure of leaf traces are de- scribed in detail, and spiral vessels are noted for the first time, these having escaped the observation of previous investigators, probably because in mature stems they are lacking next the pith, where one might expect to find them. He saw bundles in the pith of Dioon and correctly interpreted them as belonging to the vascu- lar system of the peduncle. Sortms-LAvuBACH (4) traced the vascular supply of the peduncles in Stangeria paradoxa and Ceratozamia mexicana, and also noted the formation of phellogen in the leaf bases. In his Histologische Beitrige 111, SrRASBURGER (5) describes the histological structure of a large trunk of Cycas circinalis, and gives a critical discussion of the literature. In 1896, WorSDELL (6) made a thorough investigation of a large - trunk of Macrozamia Fraseri. This form has a well-developed system of vascular bundles in the pith, described as not being con- nected in any way with peduncles. There are also concentric zones of wood, as in Cycas, and these, WorsDELL (6) believes, are rem- nants of some ancient structure which consisted of rings or layers of concentric vascular strands. To him the structure recalls that of the Medullosa stem. From these accounts we get our conventional idea of the cycad stem, with its armor of leaf bases, thick cortex, narrow zone of wood, large pith, numerous medullary rays, and no growth rings. Investigation In September 1910 I was able to study in the field the adult trunks of Dioon edule and D. spinulosum, the study being facilitated by the active encouragement of Gov. Troporo A. Denesa, of the state of Vera Cruz. The field study was supplemented by notes and material from Mr. ALEXANDER M. Gaw, of the Bureau of Information, Jalapa, state of Vera Cruz. Abundant material of Dioon spinulosum, accompanied by notes, was sent to me by Mr. J. C. DENNIs, superintendent of the Hacienda de Joliet, near Tierra Blanca, but in the state of Oaxaca. I am glad to acknowledge My 1911] CHAMBERLAIN—CYCAD TRUNK 83 indebtedness to these gentlemen, for without their cooperation the investigation of such inaccessible material would have been impossible. . MACROSCOPIC STRUCTURE The conventional account of the trunk is doubtless true for all young cycads and for most old ones, but it is not correct for large plants of Dioon spinulosum, and probably not for others which have attained any considerable height. In D. spinulosum the large amount of wood, the zone sometimes reaching a thickness of 10 cm., first attracted my attention, but since material was avail- able, it seemed desirable to examine the whole trunk. Plants were studied both at Tuxtepec and at the Hacienda de Joliet, but the following account, whenever it relates to D. spinulosum, is based upon material from the latter locality. Acr.—As mentioned in a previous paper (7), the trunk some- times reaches a height of more than 16 meters. From the crown to the base the trunk is marked with a series of ribs due to the alternation of foliage and scale leaves, the constrictions between ribs corresponding to the scale leaves, and the ribs themselves being the larger leaf bases of the crowns of foliage leaves. Ob- viously, the number of crowns which a plant has borne can be determined by counting the ribs, and, assuming that a new crown is produced each year, the age of the plant would then be known. But it is not certain that new crowns are formed every year, and whether the interval is regularly two years remains to be deter- mined. At any rate, an estimate making the number of years _ correspond to the number of crowns would be extremely conserva- tive. In our previous account (7) the age of the tallest specimens was estimated at about 400 years, the estimate assuming a crown - to be produced every other year. It was also stated that the scars are so obscure on the lower portions of the trunk that accurate counting is difficult. While this is true, we now find that the count- ing can be carried much farther than we had supposed, and also that the obscure ribs formed by successive crowns are very much closer together in the lower than in the upper portion of the trunk. The difference between the upper and lower portions of a trunk 6 meters in height is shown in figs. 1 and 2, the lower portion being taken 84 BOTANICAL GAZETTE [AUGUST 30 cm. above the surface of the rock upon which the plant was growing. The foliage display practically always consists of two successive crowns, the leaves of the lower standing transversely or beginning to droop, while those of the latest crown are more erect, but the two nevertheless presenting the appearance of a single Fics. 1, 2.—Dioon spinulosum: fig. 1, upper part of a trunk 6 meters in height; the latest crown is tied with the string, the next crown below has been cut aw ay with a machete, and the leaves of the 6 crowns below this have fallen off naturally; X¢; fig. 2, lower part of same trunk, showing scars of 21 crowns; X}. tgi1] CHAMBERLAIN—CYCAD TRUNK 85 crown. In fig. 1 the latest crown is tied to protect the bud, and the leaves of the crown below have been cut off. With this explana- tion, it will be seen that the upper portion has borne 8 crowns. The lower portion has borne 21 crowns, of which 6 or 7 toward the top are easily counted, while the rest are increasingly indistinct. How many crowns were borne by the intervening piece, about 4 meters in length, and also by the stump, is not known, but roo crowns would be a very low estimate, and the plaht would be more than 100 years old even if a new crown were produced every year. Armor.—In some forms, like Dioon edule and Encephalartos Altensteinii, the armor of leaf bases is so persistent that each leaf base is distinguishable even in the lower portion of the trunk, while in Dioon spinulosum and others the leaf bases become indistinguish- able in the lower portion of old trunks. In Dioon edule, below the two green crowns constituting the foliage display and appearing as a single crown, is a crown repre- sented by decaying midribs from which most of the leaflets have fallen, and below this will be found one or more crowns represented by irregular jagged stumps, several centimeters in length, and it is only below these that one finds the smoothly cut off bases. The reason is easily determined. As in annually deciduous dicotyls, an abscission layer of phellogen is developed, but at so late a period that only a decayed stump of midrib remains to be cut off. After the stump has fallen, a new phellogen appears a little deeper than the first, and then another, so that successive phellogens keep scal- ing off the outer surface, even in forms with such persistent leaf bases as Dioon edule. At Chavarrillo, where this species is most abundant, the trunk is often damaged by fire. In such cases, where the entire armor may be destroyed, an extensive phellogen appears in the cortex, the meristematic layer sometimes reaching a width of several millimeters, and in this way a smooth protective covering is built up. In Dioon spinulosum the phellogens are more vigorous, and suc- cessive layers are scaled off until the leaf bases in the lower portion of old trunks become indistinguishable, and even the ribs due to the alternation of scale and foliage leaves become obscure. We have 86 BOTANICAL GAZETTE [AUGUST never seen a specimen of Dioon from which all of the armor had scaled off, except in case of injury. CorTEX.—The cortex of a large plant grows rapidly for a few years, and then during the long life of the plant grows very little. In a 6-meter specimen of Dioon spinulosum, at a distance of 15 cm. below the apex, the width of the zone of cortex, measured from the outer border of the phloem to the beginning of the leaf base region, was I-1.5 cm.; while the width of the cortex near the base of the stem, where the tissues were at least 100 years older, had increased only to 1.5 or 2 cm. _ Except in cases of injury, there are no meristematic regions in the cortex, Dioon being strictly monoxylic, and there is no growth by a phellogen at the periphery, the phellogen layers being confined to the leaf base region and not reaching the cortex itself. In forms which lose their armor through the vigorous activity of successive phellogens, the cortex itself is invaded, but in such cases the invad- ing phellogen adds as much or more than it cuts off, and the stem may even increase in diameter. _ The cortex is traversed by numerous leaf traces, sonie of them direct and others forming the characteristic girdle. There are also numerous mucilage canals and cavities, some of them following the course of the bundles, but most of them being independent. Crystals of calcium oxalate are numerous, and tannin cells are so abundant that a freshly cut stem changes color in a few minutes. OUNT OF XYLEM.—The cycad stem has always been described as having a large pith and cortex, with a small zone of wood between them. According to BRoNGNIART (1), a specimen of Zamia latifolia (doubtless an Encephalartos), 1.5 meters in height and 20.5 cm. in diameter, had a pith 7.5 cm. in diameter, surrounded by a vas- cular zone 6 mm. in width, the xylem and phloem being of about equal thickness; beyond the phloem was a narrow cortex about 8 mm. in width, followed by a broad zone of leaf bases 5 cm. in width A few measurements which we have made recently are given below, all measurements being made at approximately the greatest diameter of the plant. tgtt] CHAMBERLAIN—CYCAD TRUNK 87 A plant of Ceratozamia mexicana, collected about 10 kilometers north of Jalapa, had a trunk 30 cm. high and 15 cm. in diameter. The pith, 5.7 cm. in diameter, was surrounded by a zone of zylem 3 mm. wide, with phloem 2 mm. wide, beyond which was the cortex 1.5 cm. wide, and surrounded by a heavy armor of leaf bases. A mature plant of Zamia floridana, with a stem 15 cm. in height and 6 cm. in diameter, had a pith 1.3 cm. in diameter, the zones of xylem and phloem each measuring 2 mm. in width, and the cortex about 2 cm. in width. The entire armor had disappeared, and a comparatively regular phellogen had become established in the cortex. _ A specimen of Dioon edule at Chavarrillo, with a trunk about 60 cm. in height and 21 cm. in diameter, had a pith 8.7 cm. in diameter, the zones of xylem and phloem each measuring 5 mm. in width, the cortex 2 cm., and the leaf bases 3.6 cm. A taller speci- men, about 1 meter in height, but with the same diameter, had the following dimensions: diameter of pith, 6.9 cm.; width of xylem, 1.5 cm.; width of phloem, 8 mm.; width of cortex, 3.2 cm.; width of leaf base region, about 1.5 cm. These measurements may be regarded as typical of most monoxylic trunks. The mount of wood in polyxylic trunks, though somewhat greater, is still so scanty that no exception to the con- ventional description has been necessary. Naturally, it was with considerable surprise that I noted, in the Tierra Blanca region, trunks of Dioon spinulosum with zones of wood 4,6, and even ro cm. in width. A specimen 6 meters in height, and 33 cm. in diameter at a distance of 30 cm. above the rock on which it was growing, had a zone of wood 10 cm. in width. The phloem was 1.4 cm. in width, the cortex 2.5 cm., and the armor near the base of the plant, where it had been greatly reduced, only 0.5 to 1cm. The pith at a distance of 60 cm. below the apex was 8 cm. in diameter, and from this point to the base of the plant its diameter was uniform. What the extent of the wood in a specimen 15 or 16 meters in height might be, remains to be determined. he numerous large medullary rays reaching from the pith to the cortex are a conspicuous feature of the transverse section (fig. 3). Besides the large rays there are much more numerous small 88 BOTANICAL GAZETTE [AUGUST ones. Both kinds of rays have a comparatively slight longitudinal extent. Each large medullary ray contains a leaf trace bundle, but the small rays are in no way connected with bundles. GROWTH RINGS.—Dioon spinulosum has well-developed growth rings, a feature which, so far as I know, has not been described for any cycad. These rings are conspicuous in the upper part of the trunk, and can be recognized even in the lower portions of old plants (figs. 3 and 19). That the rings are growth rings, and that Fic. 3.—Dioon spinulosum: transverse section of lower part of the piece shown in fig. 2; note the large and small medullary rays, the growth rings, and the large amount of phloem; X#. they have approximately the same structure as the annual rings of dicotyls, is obvious from a glance at a transverse section; but that they are annual rings is doubtful even in Dioon spinulosum; and in D. edule, where the rings are equally conspicuous, it is abso- lutely certain that they are not formed annually. A transverse section of the 6-meter plant of Dioon spinulosum, already mentioned, at the level of the third crown from the apex, showed four growth rings. This piece had borne one cone. A sec- tion of the same plant at the level of the eighth crown below the apex showed 13 growth rings. During the formation of the nine crowns the plant had produced at least 8 cones. tg11] CHAMBERLAIN—CYCAD TRUNK 89 The number of rings, counted 30 cm. above the ground in the 6-meter specimen, was about 150. The number of crowns, at a very low estimate, was about 100. Any estimate of the number of cones would necessarily be very uncertain, the only data being that the first cone was borne when the plant was 1 meter in height, and that a piece 25 cm. in length, taken near the top of the plant, had borne 6 cones. Estimated only upon this data, the number of cones would have been more than 100, but the estimate is doubt- less much too high, because ovulate cones are comparatively infre- quent on small plants. The number of rings, then, does not correspond exactly to either the number of crowns or the number of cones, or to the number of both combined. It is certain that in some seasons a plant produces a crown of leaves but no cone; and that it may produce a cone and no leaves; and, further, that it may produce both a new crown and a cone the same season, or it may fail to produce either a crown oracone. It is quite probable that when either a crown or a cone is produced, a ring is formed, and that when both a crown and a cone are formed the same season, only one ring is produced. We are inclined to believe that a period of vigorous growth, which would result in the formation of a new crown or cone, would produce also a growth ring, and that seasons which pass without the formation of a crown or a cone would not be marked by growth rings, the mere alternation of rainy and dry seasons not being sufficient for the formation of a ring in Dioon. If the number of rings should correspond somewhat approximately to the number of seasons, we should regard the correspondence as a coincidence, the crown and cone production being the determining factor. Of course, it is well known that dicotyls in such localities have seasonal growth rings. In Dioon edule the growth rings present a very different problem, for it is certain that they correspond to neither the number of crowns, number of cones, nor number of seasons. At Chavarrillo,. a plant 60 cm. in height and 20 cm. in diameter showed, in a trans- verse section near the base, a zone of wood 15 mm. in width. The number of rings was about 20, but the age of the plant, at a very conservative estimate, could not have been less than 100 years, go BOTANICAL GAZETTE [AUGUST hor the number of crowns less than 50, so that whatever the factor may be which produces the ring, it must appear at widely separated intervals. The trunk is obscurely ribbed, but the ribs do not cor- respond to the number of crowns, many crowns being represented in each rib. It is possible that these ribs are due to the resting periods during which neither crowns nor cones are produced. The number of rings may correspond to the number of these resting periods. It is possible that such resting periods may result in the formation of new zones of wood in polyxylic stems, like Cycas revoluta, and only in the formation of rings in Dioon edule. In either case, it would require time and some vandalism to secure evidence. ConE DOMES.—Vascular bundles in the pith have doubtless been seen by everyone who has cut a section of any mature cycad stem, but Merrentus (3), studying Dioon edule, was the first to interpret these bundles as the vascular system of the cones. Later, SOLMS- LausBacH (4) made a more thorough study of the pith bundles in Ceratozamia, and showed conclusively that the cycad trunk is a sympodium. Still later, the mode of development of the sympo- dium was described by Miss F. Grace SmitH (8), who studied the origin of young cones and stem apices in Zamia floridana. We have studied the pith bundles in Dioon spinulosum, D. edule, and Zamia floridana. In longitudinal sections of the stem, the bundles are in the form of a convex diaphragm, but since they really form a dome with the peduncle of the cone at its apex, we shall call the system of bundles a cone dome. The longitudinal section shown in fig. 4 contains five cone domes, the second of which, counting from the top, is cut through the axis of the peduncle, and the third and fifth show clearly the position of the peduncle, and the other two indicate its approximate location by a thickening of the bundles. In Zamia floridana the appearance is similar, but in Dioon edule, on account of the very slow growth, a single transverse section may show parts of as many as three cone domes. In transverse section the cone dome appears as a circle of vas- cular bundles more or less eccentric if cut near the peduncle, but concentric near the stele (fig. 5). 1911] CHAMBERLAIN—CYCAD TRUNK oI As soon as a cone begins to develop, a new meristem appears very close to the peduncle, and this new meristem may form succes- sive crowns of leaves, but sooner or later it becomes transformed into a cone, which is really only a highly modified crown of leaves Fic. 4.—Dioon spinulosum: longitudinal section near the top of the piece shown in fig. 1; note 5 cone domes and, at the tip, a part of another; three ribs and parts of two more are shown; between the ribs are scale leaves; X}. terminating the growth of its axis. The process is then repeated. An instructive view of this phase is seen in fig. 6. A little to the right of the center is the peduncle of a large ovulate cone, and at its left is the new growing point which has produced a crown of foliage Qg2 BOTANICAL GAZETTE [AUGUST eaves, and a crown of scale leaves appearing as a whitish triangular cluster in the figure, while the growing point itself is becoming transformed into a cone, a fact evidenced, as yet, only by a slight elongation, the point, while producing only vegetative leaves, ne 5: —Dioon spinulosum: transverse section at about the level of the top of fig. 4; th t ring is the cone dome; beyond this is the vascular cylinder, with the gra (quite dark) and the phloem (much lighter) about equal in width; the girdle leaf traces (/) are prominent; 4. being convex or at most hemispherical. Young cones of Zamia also may be distinguished from vegetative growing points, even before any appearance of sporophylls, by the elongation. As the new apex develops, the old peduncle is pushed aside, new tissue gradually surrounds its base, and finally whatever Tg11r] CHAMBERLAIN—CYCAD TRUNK 93 remains of the old peduncle is covered over, somewhat as in the case of a dead branch of a dicotyl. The apex of the cycad stem is remarkably broad and flat, a feature which expedites the burying of the peduncle by the new tissue (fig. 6). Fic. 6.—Dioon edule: longitudinal section of the apex of a large trunk, showing three cone domes, the lowest with bundles in transverse section, the middle one with bundles going to the peduncle of a large cone, and the upper terminating in the latest apex; x4. Cc. ee a .@©&6 Fic. 7.—Zamia floridana: ance section of apex of a large plant, showing three cone domes (c), the lower with bundles in transverse section, the middle with bundles eae to peduncle (p) of a rst cone, and the upper with bundles a young cone; the new growing point is at the right of the young cone; several ss traces ). are shown; X3. 04 BOTANICAL GAZETTE [AUGUST Fics. 8—11.—Dioon spinulosum: c, cone domes; m, mucilage ducts; /, leaf traces; ~, phloem; fig. 8, cone dome still separated from the main body of the stele; fig. 9, section at the union of cone dome and main body of stele; fig. 10, slightly more inti- mate union; fig. 11, longitudinal view of cone dome at point of union with main body of stele; all X5. 1gtt] | CHAMBERLAIN—CYCAD TRUNK 95 The vascular connections are rather complex. Naturally, each cone dome must, at some point, surround the apex of the preceding cone dome. The general course of the bundles may be seen in fig. 7, which shows three cone domes, the lowest shown in transverse section, the next terminating in the base of an old peduncle, and the upper one passing into a young cone, while at the right of the young cone is the new growing point. It is evident from this figure and the preceding one that the traces of foliage leaves first touch the stele at its periphery, while the bundles of the cone domes are on the inside. As long as the new dome is separated from the rest of the vascu- lar tissue by a zone of pith, a transverse section looks like a section of a polyxylic stem, except that the smaller zone of vascular tissue is inside (fig. 8); but a little farther down, a transverse section presents a confused array of bundles (figs. 9 and 10). After the bundles of the cone dome and those of the previously formed wood have become arranged into a fairly regular zone, a cambium is established, and the formation of secondary xylem and phloem egins. In uniting with the previously formed wood, the course of the various strands of a bundle is not uniform, some going up, some down, and others entering more or less transversely (fig. 11). It follows necessarily that every cycad which bears terminal cones must have cone domes in the pith. This would include all the living cycads, with the single exception of the ovulate plant of Cycas, in which the sporophylls are borne in a loose crown like the foliage leaves, and the growing point is not transformed into a cone, but remains meristematic. It is possible that in specimens of Encephalartos, which produce several cones in a circle, the meristem remains as in Cycas. In such a case, no cone dome would be formed; but if at any time such a plant should produce only one cone, or two or more cones in a cluster, a dome would be formed. In Macrozamia Fraseri, WoRSDELL (6) found numerous bundles in the pith, but claimed that they had no relation to cones. This species usually bears only a single cone, and consequently must have cone domes in the pith. It is possible that WorsDELL’s plant, being a greenhouse specimen, may never have produced a cone, but Dioon edule, which elongates very slowly, may show as [AUGUST , BOTANICAL GAZETTE 6 . Bf a: cg. be b BS +: 4 E AG obo , fig. 12, longitudinal section of mature wood showing apparently compound nature of the large ray at th Fics. 12-14.—Dioon spinulosum: e upper portion, the bundle crystals; fig. 13, longitudinal radial section; fig. 14, transverse section; all X 25. Ig11] CHAMBERLAIN—CYCAD TRUNK 07 many as three cone domes in a single transverse section of the trunk, and the arrangement of pith bundles resembles that described for Macrozamia. Since the question would be settled by a glance at a longitudinal section of a cone-bearing Macrozamia trunk, it is hardly worth while to speculate. HISTOLOGICAL STRUCTURE The living trunk of Dioon spinulosum cuts rather easily with an ax or machete, but is amazingly difficult to saw. Microtome sections of fresh material are not hard to cut, but transverse and longitudinal sections are likely to break at the large fragile medul- lary rays. A general view of the histology of the wood is shown in figs. 12-14. XYLEM.—The xylem, in the older parts of the stem, consists principally of very long tracheids, and is traversed by large and small medullary rays. Some writers state that there is no protoxylem in the adult cycad trunk, but the statement obviously rests upon a mistaken notion as to the character of protoxylem, such writers. assuming that only spiral and annular vessels should be entitled to the name, instead of applying the term to the first xylem differentiated in a bundle, without respect to the character of the markings on the cell walls. The adult stele of Dioon spinulosum is endarch, and the protoxylem consists of scalariform tracheids which pass gradually into the pitted tracheids with pointed ends, constituting the prin- cipal mass of the xylem. The transition is unmistakable, the scalariform markings, elongated pits, and typical bordered pits sometimes being found in a single tracheid. The bordered pits are multiseriate, two, three, and even five or six rows being found in a radial view of a tracheid, so that in radial sections the wood might be mistaken for that of Araucaria (fig. 15). Pits are occa- sionally found on the tangential walls, but they are not numerous and are irregularly scattered. Besides the tracheids with pointed ends, the xylem contains elongated cells with transverse walls (figs. 12 and 15-17). These at first are thin-walled and contain starch, but later may or may not become lignified and pitted. They are not uniform in length 98 BOTANICAL GAZETTE [AUGUST or constant in position, although they are most numerous in con- tact with the medullary rays (fig. 12). That their origin is the same as that of the ordinary pitted tracheid is seen at once in a transverse section of the wood (fig. 17). Still another form of tracheid is found in the large medullary rays (fig. 18). These tracheids are scalariform, are irregular in outline, and are nearly erect at their upper end, but become nearly Yu WS al UU CS) aN we LOE y) Ny) @ ) OK OVS i yo Ww WY IN \( - Ss IN © + IG. 15.—Dioon spin ro > 4 J 3 . horizontal deeper down in the ray, so that a tangential section of the ray shows them in both longitudinal and in transverse section. Every large medullary ray would show these peculiar tracheids at some point or other, and they are particularly numerous near the pith. They connect the leaf trace bundle, which is found in every large ray, with the secondary xylem, a connection hitherto unknown in cycads. Such a secondary connection of the leaf trace is a prominent feature in angiosperms. Professor R. B. THOMSON examined preparations of the large medullary rays, and Tgtt] CHAMBERLAIN—CYCAD TRUNK 99 I am indebted to him for the suggestion in regard to their connec- tions. The growth rings, to the naked eye, appear almost as distinct as in dicotyls, but under the microscope they are not so conspicuous (figs. 19 and 20). The latter figure presents one of the most con- a as Be.- 20 Losey SOS Sor OTS rOlTg, © 1 s _. 1 ee | —< f moatiure (t) containing starch, the xylem tracheids, Fics. 16, 17.—Dioon spinulosum: fig wood, showing thin-walled cells of the xylem and the small medullary rays containing starch and calcium oxalate crystals; transverse section showing the phloem with several thick-walled cells, xylem thick-walled tracheids and several of the thin-walled cells (f); x, calcium oxalate crystal in medullary ray; both X125. spicuous rays which could be found. In Dioon edule, the rings appear about the same to the naked eye, but under the microscope are quite distinct, and seem to differ considerably from those of D. spinulosum, as might be expected from the description given in i ole) BOTANICAL GAZETTE [AUGUST connection with the number of rings. I have not yet found time to give them a careful study. In the plant of Ceratozamia, already referred to, the cells of the xylem are quite uniform, there being no trace of growth rings, and a similar condition was found in several stems of Zamia floridana. i. ‘S Geta tt ER SLOSS ce 225 = Wes o80,7 F Fic. 18.—Dioon spinulosum: portion of large medullary ray, showing the tracheids indicated in tangential section at the tip of the large ray in fig. 12; somewhat above the scalariform tracheids are pitted tracheids of the secondary wood; the lower third of the figure shows part of the leaf trace bundle in the ray; many cells contain calcium oxalate crystals; X40. PHLoEM.—The phloem was overlooked by BRonGnrART, doubt- less on account of its great extent and the numerous bast fibers which makes it resemble the wood. A small portion of the xylem, the cambium, and asmall portion of the phloem of Dioon spinulosum are shown in fig. 17. The extent of the phloem is indicated in the photomicrographs (figs. 3, 4, and 8-10). In longitudinal section, especially in tangential section, the resemblance to the wood is tort} CHAMBERLAIN—CYCAD TRUNK IoI even more striking, the medullary rays being just the same, and the bast fibers having about the same arrangement as the long tracheids of the xylem. This structure makes the phloem nearly as rigid as the wood. Fic. 19 Fics. 19, 20.—Dioon spinulosum: fig. 19, photograph showing growth rings, x; fig. 20, a single growth ring (g); 125. Rays.—In a transverse section the large medullary rays are as conspicuous as those of Quercus, and the small rays, while not nearly so conspicuous, are readily visible to the naked eye (fig. 3). The small rays vary greatly in longitudinal extent, some showing only a single cell in tangential section, while others may show more than 50, and may reach a width.of 3 or 4 cells. The great 102 BOTANICAL GAZETTE. [AUGUST majority of the small rays are less than 20 cells in longitudinal extent, and are one or two cells wide, often two cells wide in the middle and one cell wide at both ends (fig. 12). Radially, the rays extend from the pith to the cortex, few if any new rays being formed as the trunk grows. Most of the cells contain large starch grains, but some have crystals of calcium oxalate, which is also abundant jn the phloem, cortex, and pith. The large rays also extend from the pith to the cortex. Longi- tudinally, they measure 4 to 8 mm., and from a width of about 1 mm. in the middle they taper to a single cell above and below. In each large ray is a leaf trace, with its phloem more or less dis- organized. The xylem of this bundle is usually uppermost, but the orientation is various until the bundle reaches the cortex, where it becomes a part of the characteristic girdle. From both the pointed ends, tracheids extend into the ray, often making nearly half of the ray look like a group of small rays (fig. 12). Most of these tracheids which extend into the rays are scalariform, but some are slightly pitted, and some are the cells of the wood with transverse walls already described. Every large ray has at least one mucilage duct, and surrounding it at a distance of a few cells, the calcium oxalate crystals are particularly abundant. While the large ray, especially in tangential section, resembles the broad ray of Quercus, as described by EAmeEs (9), its mode of formation is different, the broad ray of Quercus originating by the fusion of small rays, while in Dioon the broad ray owes its origin to the leaf trace which it contains. The tissues simply grow around the leaf trace, and the compound appearance of the ray, shown at the upper end of the photomicrograph (fig. 12), is a secondary, not a primary feature. COMPARATIVE HISTOLOGY.—The trunks of Dioon spinulosum, D. edule, Ceratozamia mexicana, and Zamia floridana have some histological characters in common, and it is probable that all the Cycadales have enough histological peculiarities to identify the order by the structure of the trunk. The four species mentioned above are easily distinguished from each other by such histological characters, but it is very doubtful whether nearly related species of a large genus like Zamia could be so distinguished from each rgr1t] CHAMBERLAIN—CYCAD TRUNK 103 other. The distinction would doubtless be mu more difficult in young trunks than in old ones. The structure of the trunk of Dioon spinulosum is remarkably like that of the Bennettitales. The growth rings resemble those of Cycadeoidea Jenneyana, as described by WIELAND; the phloem, with its numerous thick-walled fibers in transverse section, is very similar to that of Cycadeoidea Wielandi; and the xylem, as it abuts upon the pith, also resembles that of Cycadeoidea. But there are also contrasting features; the broad medullary rays are not figured in the Bennettitales, and in the xylem cells with trans- verse walls seem to be lacking. Summary 1. The paper deals with field material of adult stems of Dioon spinulosum, D. edule, Ceratozamia mexicana, and Zamia floridana, particular attention being given to Dioon spinulosum. 2. In Dioon spinulosum the xylem zone in a plant 6 meters in height reaches a width of 10 cm., far exceeding the extent of any xylem zone previously described for any cycad. _ 3. Dioon spinulosum and D. edule have growth rings, which in D. spinulosum correspond to the periods of activity which result in the formation of crowns or cones, but which in D. edule do not correspond to such periods. No growth rings were found in Ceratozamia mexicana or Zamia floridana. 4. Cone domes in the pith were studied in the four species. 5. The histological character of the adult stem was studied in Dioon spinulosum. The protoxylem consists of scalariform tracheids, from which there is a gradual transition to the tracheids with multiseriate bordered pits, constituting the principal part of the wood. There are also cells with the same origin as the pitted tracheids, but with transverse walls which may remain thin-walled and contain starch or may become lignified. Besides the leaf trace bundles, scalariform tracheids are found in the large medul- lary rays. 6. Both in the general appearance of the transverse section and in histological characters the adult trunk of Dioon spinulosum resembles that of Cycadeoidea. oe sgn 104 BOTANICAL GAZETTE [AUGUST wv au ~JI LITERATURE CITED . BRONGNIART, A., Recherches sur l’organization des tiges des Cycadées. Ann. Sci. Nat. Bot. I. 16:389-402. pls. 20-22. 182 Q. . Von Mout, Huco, Ueber den Bau des Cycadeenstammes. Abhandl. K. Acad. Miinchen 1:397-424. 1832 . Metrentvus, G. H., Beitrige zur Anatomie der Cycadeen. Abh. K. Sachs. Gesell. Wiss. '7:565-608. pls. 1-5. 1861. . Sotms-Lausacu, H., Die Sprossfolge der Stangeria und der iibrigen Cyca- 890. deen. Bot. Zeit. 48:177-187, 193-199, 209-215, 225-230. pl. 2. 1890 STRASBURGER, EDUARD, Histologische Beitrage III. 1891. . WorsvELL, W. C., Anatomy of stems of Macrozamia compared with that of other genera of Cycadeae. Annals of Botany 10:601-620. pls. 27, 28. 1896. age Cuas. J., Dioon spinulosum. Bot. GAZETTE 48:401-413. * Sigs. 1-7: 8. SMITH, eile GRraAcE, Morphology of the trunk and development of the microsporangium of cycads. Bor. GAZETTE 43:187-204. pl. 10. 1907. E THUR J., On the origin of the broad ray in Quercus. Bot. Gaseere 49:161-167. pis. 8, 9. 1910. A BOTANICAL SURVEY OF THE HURON RIVER VALLEY VIII. EDAPHIC CONDITIONS IN PEAT BOGS OF SOUTHERN MICHIGAN GEORGE PLUMER BURNS (WITH EIGHT FIGURES) In a paper read before the Society for Plant Morphology and Physiology at the Philadelphia meeting (1904), the author called attention to the fact that the plants in peat-forming lakes near Ann Arbor, Michigan, are by no means all xerophytic. With xerophytes are found many plants whose structure is either meso- phytic or hydrophytic, and the conclusion was drawn that in the vicinity under consideration one should no longer refer to a peat bog, as such, as a xerophytic habitat (2). TRANSEAU (17), in a very interesting paper dealing with the distribution of bog and swamp plants, stated that the two were found growing together in the bogs of southern Michigan, and accounted for the present mixture of the two kinds chiefly on historical and climatic grounds. PENNINGTON (13) concludes that the bogs in southern Michi- gan are heterogeneous habitats and demand detailed study. LivincsTon (12), DacHNowskI (7, 8), and TraNseav (18) in experimenting with bog water have found that it is not the same in all zones. The samples of water taken for experimental purposes were generally from under Larix, Drosera, Sarracenia, Andromeda, Cassandra, Vaccinium, Eriophorum, etc., that is, from zones with marked xerophytic plants. The distribution and position of zones of plants in the bogs of southern Michigan have been given by Davis (9), TRANSEAU (18), the author (3, 4), and others. On the side of greatest depth the following zones are found: I. Zone of submerged planis——Plants in this zone usually do not go to great depths. In many lakes no vegetation is found at a depth of 12 feet (3.66 m.). The chief plants aré Chara, Cera- 105] {Botanical Gazette, vol. 52 106 BOTANICAL GAZETTE [AUGUST tophyllum demersum, Naias flexilis, Potamogeton lucens, P. natans, P. zosieraefolius. II. Zone of water lilies —This zone is confined to shallow water seldom over 5 feet (1.5 m.) in depth. The characteristic plants are Castalia odorata, Nymphaea advena, Brasenia Schreberi. Ill. Zone of floating sedges—The mat formed by these sedges is very firm and usually about 18 inches (45.8 cm.) in thickness. The chief mat-forming plants are Carex filiformis and C. oligosperma. Associated with these, some playing an important part in mat- formation, are Menyanthes trifoliata, Dulichium arundinaceum, Eriophorum viridi-carinatum, Drosera rotundifolia, Aspidium Thelyp- leris, Onoclea sensibilis, Equisetum limosum, Eupatorium pur- pureum, E. perfoliatum, Mentha arvensis var. glabraia, Scutellaria galericulata, Utricularia sp., Calopogon pulchellus, Campanula aparinoides, Arethusa bulbosa, Galium trifidum, Aster junceus, Potentilla palustris, Solidago serotina var. gigantea, Lysimachia terrestris, etc. IV. Zone of bog shrubs—The characteristic plants of this zone are Chamaedaphne calyculata, Andromeda polifolia, Betula pumila, Nemopanthes mucronata, Sarracenia purpurea, Vaccinium Oxycoccus, V. macrocarpon. V. Zone of tamaracks.—The principal plants are Larix laricina, Cornus stolonifera, Osmunda regalis, O. cinnamomea, Rhus Vernix, Aster junceus. In areas where the tamarack is thick there is no undergrowth. VI. Zone of poplars and maples——This zone is often of great width for reasons pointed out in a previous paper (4), and has the greatest variety of species of any zone. Some of the plants found are Acer rubrum, A. saccharinum, Populus tremuloides, P. grandidentata, Prunus serotina, Quercus rubra, Q. bicolor, Sam- bucus canadensis, S. racemosa, Salix discolor, S. rostrata, Spiraea salicifolia, Cornus stolonifera, Ilex verticillata, Cephalanthus occi- dentalis, Rosa carolina, Epilobium adenocaulon, Verbena hastata, Solanum Dulcamara, Polygonum sagittatum, P. hydropiperoides, Geum rivale, Rumex britannica, Impatiens biflora, Viola blonda, Solidago canadensis, S. graminifolia, etc. VII. Zone of marginal willows.—Salix nigra, S. lucida, S. dis- tg1t] BURNS—HURON RIVER VALLEY 107 color, Cornus stolonifera, Ilex verticillata, Rubus idaeus var. acu- leatissimus, R. hispidus, R. villosus, Rosa carolina, Vitis vulpina, Alisma Plantago-aquatica, Acalypha virginica, Agrostis alba, Bidens cernua, Cicuta bulbifera, Carex vulpinoidea, C. scoparia, Eleocharis tenuis, Eupatorium perfoliatum, Geum strictum, Glyceria nervata, Juncus effusus, Lycopus americanus, L. virginicus, Lactuca cana- densis, Ludvigia palustris, Pilea pumila, Polygonum Hydropiper, Fic. 1.—First Sister Lake near Ann Arbor, Mich.; the photograph shows the zonal arrangement of plants at the southwest corner; five zones can be distinguished as follows: water lily, bog sedge, bog shrub, tamarack, maple-poplar; the adjacent uplands are covered with oak-hickory woods; photograph by STEELE. P. sagittatum, Penthorum sedoides, Ranunculus pennsylvanicus, R. scleratus, R. delphinifolius, etc. (fig. 1). A study of the partial lists given above shows that they are not all xerophytes. There are at most only three. zones which have bog flora as the characteristic plants. These are the floating sedge, the bog shrub, and the tamarack zones. In the first of these only those plants rooting deep in the mat can be called bog xerophytes; those rooting in the surface layers are hydrophytes. The other zones are occupied by hydrophytes or mesophytes. 108 BOTANICAL GAZETTE [AUGUST The flora of the postglacial lakes studied in southern Michigan may be classified thus: : Submerged plants sarorper Water lilies Floating sedges Xerophytes } Bog shrubs Tamaracks Vegetation in postglacial lakes Hydrophytes or tnesophytes 1 Poplar-maples Hydrophytes Marginal willows An investigation has been carried on for several years by the author and some of his advanced students to determine as far as possible the edaphic conditions in the different areas outlined above. A short report has been given (5) and a more detailed account of some of the results is given in this paper." Temperature The aerial parts of the bog plants are subjected to great extremes in temperature. Situated, as they are in the area under discussion, in low basins with often very steep sides, the air from the adjacent uplands drains into them, producing a temperature several degrees lower than that on the surrounding uplands during the night and early morning. During the day, however, very high temperatures have been recorded. Such temperatures have also been recorded by GANONG (10, 11) in New Brunswick. Unless otherwise stated in the text, all temperature readings given in this paper, both for soil and air, were taken with Richard Fréres, Paris, thermographs belonging to the University of Michigan. These instruments are shown in fig. 2 in the shelter in which they were kept in the field. The one on the left records the air, the other the soil temperatures. It was found, unfortu- nately, that the soil thermometer was unreliable when the tempera- * Bog conditions in southern Michigan, rai lies toward the southern limit of their distribution in this country, seem to be quite different from bog ae farther north described by GANONG (11). i point was emphasized also b TRANSEAU (17, 18). See also BAstrIn and Davis (1). Ig11] BURNS—HURON RIVER VALLEY 10g ture of the air fell near the freezing point, and hence the early spring and late fall data were untrustworthy. In any temper- ature of the air ranging above 7° C., the records were found to be reliable. The temperature of the air at First Sister Lake, in the floating sedge zone, compared with that on high ground in Ann Arbor at 7 A.M. is given below. Fic. 2.—Thermographs in the bog shrub zone at First Sister Lake; the one on the left is headin air, the other soil temperature; photograph by STEELE. TABLE I DIFFERENCES IN TEMPERATURE IN BOG AND UPLAND; BOTH RECORDS WERE MADE WITH THERMOGRAPHS WEEK HIGHEST LowEstT Bog Upland Bog Upland April 26- May ee be ig © 14°7C —1°C, a°4 C. 3—May to. 0. ter: 7 10.1 4 9 Mace 10-Msy Boe | II 18 —I fe) May t7-May G4 on yous 10 14.2 —2 3.6 Table I shows that in the morning the temperature of the air in the bog is several degrees lower than that of the upland. The only exception in a much larger collection of data than published IIo BOTANICAL GAZETTE [AUGUST here was seen in the lowest point reached during the second week when the upland went to 0, while the bog remained 4° warmer. The records of the thermographs show wide variations in air temperatures. In 1907, during the week April 26—May 3, it ran from 21°5 C. to —4°5 C.; in 12 hours it rose from —4°5 C. to 16° C.; May 11, from 6 a.m. to 8 A.M., the air was —4° C.; May 13 at 1 P.M. it reached 28° C.; May 16 at 3 A.M. it was only 1°5 C. Low temperatures were recorded during the summer. On June 28 the air got as lowas 4° C. July (1907) was the hottest month, judged from the lowest temperatures reached, the lowest for the month being 7° C. at 6:15 A.M. the 27th. In August the low records Were: the tst.9 C.; 3d,6 C.; ath, 6° C.; 13th, 7° C.; 22d, 3°5C.; 25th, 5, C. August 6, 1904, a maximum-minimum thermometer was hung in the top of an 8-foot tamarack in the sedge zone at Dead Lake. It showed a maximum of 37°8 C. and a minimum of 57s C. These figures show that the temperature of the air is compar- atively low during the entire summer during the night. The coldest time came at 1 A.M. or about 7 A.M. On the other hand, day temperatures may run very high. The hottest time of the day was about 1 P.M.; it seldom came as late as 2 P.M. Fig. 3 repro- duces the air record for the week July 2-9, 1906, taken in the floating sedge zone at First Sister Lake. The temperature of the soil, on the other hand, shows very slow variations during the season. There is great difference in soil temperatures at different depths, and they warm up very slowly, except for the shallow surface layer; they never get very cold. When making contour maps of the bottom of these lakes (3, 4) in winter, it was soon learned that although the ice might be 10 inches (25.3 cm.) thick over open areas, a good thrust of the drill would usually send it through the thin ice near and beneath the tamaracks. Even in most severe weather it was necessary to wear rubber boots, as the thin ice continually broke under one’s weight. What ice is formed, however, lasts long into the spring. . In taking soil temperatures, a square piece was sawed out of the peat and carefully removed. The long bulb of the thermo- Ig1t] BURNS—HURON RIVER VALLEY III graph was then inserted in the side of the opening parallel to the surface for about 18 inches (45.8 cm.), and the piece of peat was replaced. The surface arrangement was left as nearly normal as possible. Some of the records were made at Dead Lake, but most of them were made at First Sister Lake. in 555533° 2:52 BE: waae baa? 422 ie 332 5 eiiiet an idl lituubasa LEE fi Puta a capemnee ie ave SiEScaeGatdeugetses SUGUNMERESEERSESESS an 233 ie STL SUETHLNE nT SES EuG DENEES UE SER NESEEA AREEEE REREEE Sau a fii Veit Hci “AME Hay ee Hi ett Fic. 3.—Temperature record of the air for the week July 2-9, 1906, taken in the sedge zone at First Sister Lake; the highest was 31° C., the lowest 3°5 C.; this occurred about 5 A.M., July 6. Fig. 4 shows a partial record of the results which were obtained at the latter lake at different depths in the tamarack zone. A is taken from the figures of TRANSEAU (18, p. 421) and gives the readings at a depth of 1 inch (25 mm.). At this depth the rise in temperature is quite rapid and resembles that of the adjacent uplands. At the time the leaves began to appear, May 27, it had reached 17° C. Line B gives the record for a depth of 4 inches APRIL MAY JUNE SJULY AUG. 4g _ [4 4 / 3 i 2. Z, 1-4 /o ea a 8 OS ee : --C ee POT -D Fic. 4.—Diagram showing variation in temperature at different depths and at different seasons in the tamarack zone; A, 25 mm.; B, 10.2 cm.; C, 20.4 cm.; D, 45.8 cm. below the surface. (10.2 cm.) to June 1. The temperature at this point does not rise so rapidly as that just given, and on May 25 had reached 9° C. The dotted line C gives the temperature at 8 inches (20.4 cm.). This record shows that during the spring, when leaves are unfolding, the soil temperature at this depth remains compara- tively low; not until July 22 did it reach 14° C. This was held for about a month (July 22—August 24), when it gradually began oka? BOTANICAL GAZETTE [AUGUST to lower. The readings given in line D were taken 18 inches (45.8 cm.) below the surface, and were continued for only a short. time; the temperature was surprisingly low. The next figure (fig. 5) was furnished by Mr. HAROLD STEELE, and gives the results of short readings in several zones. These readings were made in 1904 at the same lake. The soil readings LUEY Se, See Fe” | AS GR GR +” Tele" ¢ MP a 30 \ N\_A STAI A ‘ Wes VV oO SHRUB BOG-SEOGE. a Ss ap a AUGOS FT: 24 25 2 7-2 30 3 / ae | 20 NA at f ps eh A, ! V/ u Oo TAMARACK POPLAR Fic. 5—Temperature reading taken in different zones at First Sister Lake by STEELE, in summer of 1904; explanation in text. are taken 18 inches (45.8 cm.) below the surface. This shows that the soil under the tamaracks is the coldest. The same is reported by TrANsEAU (18). As the writer had only one set of thermographs at his command, the readings could not be made simultaneously, but the data gathered seem to show that this made little difference in this case, as the temperatures were sta- tionary. The soil temperatures were: tamarack, 6 C.; bog shrub, 7°5 C.; poplar, 7°5 C.; and bog shrub, 10° C. These tg11] BURNS—HURON RIVER VALLEY 113 temperatures for the last two were lower than the author obtained for these zones. As has been pointed out, there is great variation in the poplar zone, and one should have a better knowledge of the exact location before attempting to explain this difference. The temperature under the bog sedge also varies with the width of the floating bog and the proximity to the zone of bog shrubs. That is, the temperature remains more constant when one gets away from the open water. Average records made by a class with ordinary thermometers for six weeks in the summer of 1906, 3 inches (7.6 cm.) below the surface, were as follows: open water, 18° C.; bog sedge, 17° C.; tamarack, 15° C.; maple-poplar, 17° C.; marginal willows, 18° C.; outer edge of marginal zone with no shade at 1:15 P.M., 22°C. These readings show a wide divergence of soil temperatures in the zones under consideration, and also at different depths in the same zone. This calls for a study of the depth of the root systems. For example, the high temperature of the soil at 25 mm. repre- sents the condition for germination of the many seeds of “drained swamp” plants which yearly lodge in the bog. This taken with the weak light and humid air, which will be considered later, makes an excellent place for germination of these seeds. On the other hand, the study of the root system shows that temperatures found at a depth of 45.8 cm. in the bog sedge and tamarack zones, especially, could not have a direct influence on the plants growing above, as they did not root in that layer but only in the surface layers. This is true even of the largest trees. Added to this fact is the additional consideration that peat is a very poor con- ductor of heat. The soil readings in these zones which are of the greatest importance are those taken near the surface in a study of reproduction, and those at moderate depths in the study of the present flora. These data become ecologically important in the light of the work of TRANSEAU (18, p. 22), who has shown by experiment that a temperature of 10°8 C. causes a diminution in the develop- ment of both roots and leaves. Although the trees began to open their buds the last of May, it was not until July that the tempera- ture about the roots of the tamaracks reached a higher temperature. I14 BOTANICAL GAZETTE [AUGUST This was after the most active vegetative period. Conditions in the bog shrub zone closely resemble those just described. In bog sedge the records show less regularity and resemble more closely swamp conditions, especially, as has been said before, in bogs where this zone is narrow. In the two outer zones, the temperatures recorded resemble more closely the upland and drained swamp conditions. Here they ranged about 18° C., in July reaching this mark early in the summer. They would have a less detrimental effect upon the root systems of the plants in these zones. HEE fe feudal ze = are F2gees8 rt Arbor, Mich; August 23-30, 1907; the instruments were in the bog sedge zone; the bulb of the soil thermograph was 20.4 cm. below the surface; the upper line shows record of the air, the lower the soil Deneck Fig. 5 also shows the range of air temperatures for the periods given above. The results are similar to those already given by the author. The record of the soil and air thermographs for one week, August 23 to August 30, is reproduced in fig. 6. This is only one of numerous records which were taken, and shows the very slight variations in the temperature of the soil and the great variations in the temperature of the air. The greatest variation in soil was about 1° C.; that of the air was 17° C. In fig. 3, the varia- tion in air temperature was 25°5 C. tort] BURNS—HURON RIVER VALLEY II5 Water table The variations in the position of the water table from year to year and from month to month play a very important part in the succession of plant societies in these bogs. In 1908 the level of the water in all bogs of southern Michigan was high. In 1901- 1904, When the maps of Dead Lake were made (3), there was an island near the center, and it was customary to row out there and leave the supplies when working at the lake. That island in 1908 was submerged, and one could row over it in 18 inches (45.8 cm.) of water. The flora of upland forms had disappeared with the exception of some stunted willows, and in its place were a few potamogetons, chiefly. P. helerophyllus. At Whitmore Lake, north of Ann Arbor, the same rise in water has occurred, and what was a peninsula in 1904 is now an island. The same fact is recorded by Davis (9, p. 162). During a series of wet years the change in water level affects the vegetation in all zones except perhaps on the lakeward side of the floating sedge, which rises and falls with every change of level. Along shallow shores the factor is sufficient to control the char- acter of the vegetation, as has been pointed out in the case of the island at Dead Lake. Its influence is also profound in those zones where the peat is solid. It may rise above the surface to a depth of several inches. With this rise there is also found an increase in the humidity of the air. During such periods Sphagnum sp. spreads rapidly toward the shore and may assume quite an impor- tant position in all zones except perhaps the marginal. An inter- esting example of the behavior of this moss during wet and dry periods is found at Mud Lake. Here a section was made which showed alternating layers of Sphagnum and Polytrichum corre- sponding to the wet and dry periods of previous years. As many as four layers were easily distinguished at Mud Lake. In one case measured the shrubs stood in water which was 18 inches (45.8 cm.) deep one summer, and in water of various depths less than that for a period of at least three years. These plants then must be able to endure submergence for a long period, as has been pointed out by Davis. 116 BOTANICAL GAZETTE [AUGUST During wet periods bog plants show a tendency to move shore- ward. This is due to local conditions rather than to historic factors. Such movement is only temporary. In the summer of 1909 the island in the center of Dead Lake had begun to reappear. During the late summer the ground appeared in the higher parts, showing that the water level was get- - ting lower. In less than ten years the island disappeared and in part reappeared, which indicates that these wet and dry periods may be of short duration. This is contrary to the belief, often expressed, that in southern Michigan they last about thirty years each. The effect of the dry periods upon vegetation is also very marked. The relation of such periods to plant succession has been emphasized by Davis, who believes that they offer an explanation of the xerophytic structures of bog plants (9, p. 160). During such periods the surface layers of the peat become exceed- ingly dry; this may extend to a depth of several feet. Fires which reduce the surface several feet are of common occurrence. The effect of fires upon plant succession has been given by PENNINGTON (13). : During this time there is very little water available in these surface layers for plants, and, as it will be shown later that the movement of water in peat is slow, it can easily be seen that the ‘habitat is very dry, even omitting the usual factors of humus acid, low temperature, bog toxins, etc. The following table is given by Davis taken from WARRINGTON (19). TABLE II PARTS OF WATER PER 100 PARTS OF DRY SOIL Type of soil When plants wilted cared gag Coarse Sandy 6.0.2. ce es 1.15 Sandy panien..; .. 2... sc. 4.6 .00 ine humus sand... 6.6.55 6.2 3-98 Sa WO Soe es 7.8 5.74 RUIN, 5s eS 55 ck cs vs 9.8 5.20 Bec ek ip akecss 49.7 42.30 Davis says: “If these results are correctly reported, it appears that peat may appear very wet and yet contain no water for plants growing in it, so that tg11] BURNS—HURON RIVER VALLEY 117 those plants which habitually grow at levels of peat bogs, where the surface strata can dry out, must have xerophytic adaptations if the climate is such that drying out of these levels may occur.” In addition to the variation in water level due to wet and dry periods, there is the variation from month to month during each year. This difference is shown in fig. 7, which gives the results obtained April 20-August 3, 1905, in the zones at First Sister Lake. The data were gathered for the most part by STEELE. Holes were MAY SUNE SULLY AGG. 20 = ea et eos 27 2 z S28 Os 2a oe 20 2, TE /O “Sa /O Yo) ay : a 2 oO sot Se td i! Ss /O ba Ste \’-+ > fen he aL. 20 i AE at Se 30} fat ah ~ 30 a CRE nae ZO I 50} ad Fei 6 ; ae WATEA TABLE Fic. 7.—The results of measurements taken to determine the variations in water table in the different zones at First Sister Lake; variations are given in dug in the peat of the different zones to a considerable depth, and a stick placed in a horizontal position at the top. From this stick measurements were taken daily to the top of the water standing in the holes. These were plotted and the result shows in the figure just given. The bog sedge zone shows practically no variation, although there would have been some, especially on the landward side, had the measurements been started very early in the spring. This however would be too early to affect the vegetation. The open water shows some variation in the summer, but the bog 118 BOTANICAL GAZETTE [AUGUST sedge rises and falls with it, and there is little variation during the growing season. The other zones show a gradual lowering of the water table, beginning quite rapidly June 8 and continuing until July 3. At this time a heavy rain fell, raising the water level sharply in all zones. After this there was a rapid lowering of its position in all zones until the close of measurements, except in the bog shrub; this showed a slight rise. The greatest variation, as has been said, was in the marginal zone. On April 20 the water was 7.2 inches (18 cm.) above the surface of the peat. This gradually lowered until the water table was 38.4 inches (96 cm.) below the surface. A variation of 45.6 inches (113 cm.) was recorded.? In the maple-poplar zone the variation was 18.4 inches (46 cm.); in the tamarack zone, 12.4 inches (31 cm.); in the bog shrub zone, 6.8 inches (17 cm.). These figures show that the loose peat acts as a dam, holding the open water in the lake from flowing back to the outer zones. The same fact was reported by a former student (14) at the small bog near Carpenter’s Corner. Here a central area was found with the characteristic bog flora of this region, while the greater part of the original lake was occupied by a mixed flora, with red maple and poplar as the dominant trees. This seemed to be an example of the “lagging behind of a xerophytic group of plants in a hydro- phytic habitat,’ but borings showed that the water table was only 1.4 inches (6 cm.) from the surface. The temperature of the soil and character of the peat were the same as generally found under such plants. A few rods to the east, under the maples, the water table was several feet below the surface. An excellent example of the holding back by peat of the water in a lake was related to me by a former student, after he had examined the above chart. A farmer living near his home had a peat bog with a very wide marginal zone and a low shore of con- siderable width. During dry years he was able to cultivate this ground with good returns, but during wet years he always lost his crop. Accordingly, in order to secure continuous use of his ? In the report in Science N.S. 29: 269, the height of the water above the surface should have been added, making a total of 113 cm IIT] BURNS—HURON RIVER VALLEY SIO land, he dug a ditch from the margin to the open water during the dry season of 1903. As soon as his ditch was opened, the water flowed from the open lake to the margin and he lost the use of the land entirely. These examples show that there is very little movement of water in peat. The water may be several feet higher in one zone than in an adjacent one; the difference in height depends upon the nature of the peat. This fact is well known to persons traveling on northern bog areas. The variations here shown to occur in the position of the water table in different zones during the summer and in the same zone during the season, bring very strong additional proof to the state- ments of Davis regarding the xerophytic structures of bog plants, which were quoted above in the discussion of bogs during a dry period of years. During the season the plants growing in these bogs are subjected to high water level in the spring, when the water table in all zones is approximately level with the open water of the lake. During the hottest and driest months of the summer the water supply is greatly reduced by a lowering of the water table, and when water is removed by the surface layers, it is very slowly replaced by that of the deeper parts. It is only in these surface layers that these plants root. In any bog where a clearing of any extent has been made, one finds areas where the tamaracks have been blown over during storms; these show that even the largest trees root in the surface layers only. It has been shown in fig. 7 that the water table in the various parts of the bog stood at different heights during the summer. This is the controlling factor which makes the bogs in this region heterogeneous habitats, supporting xerophytes in three zones and hydrophytes or mesophytes in other zones. The first effect of lowering the water table, as has been pointed out, is to make the habitat xerophytic, and one would expect that those areas where the water table is lowest would be most xero- phytic. A glance at the plants shows that this is not the case; the outer zone in this lake is occupied by hydrophytes. This is due to secondary changes. Immediately after the water lowers, a number of other changes set in which produce the opposite 120 BOTANICAL GAZETTE [AUGUST effect. With the decrease in the position of the water table, there is an increase in the oxygen supply, the number of soil organisms, and a rise in temperature. These produce a change in the compo- sition of the peat, making water more and more available for plants and making the habitat less and less xerophytic. In older parts where this process has been going on for years, there is a decrease in the volume of the peat and a lowering of the surface. In the areas studied around Ann Arbor, this seems to be the explana- Fic. 8.—Station under the tamaracks, showing ee almost entirely dead; the light value here was 0.033; photograph by STEE tion of the marginal ditch characteristic of bogs there. In other areas different reasons have been given, but they do not seem to explain the condition found in this region (16). During wet periods the width of this ditch is often greatly increased, as has been pointed out previously. In such an area only those plants can grow which can stand high water during a term of wet years and high water during the spring of every year. The vegetation which is found here is much the same as that found under these conditions along the borders of our streams. The peat found tg11] BURNS—HURON RIVER VALLEY phe below the lowest level to which the water table gets in the driest times is red, while that above varies from red to brown and black. As has been pointed out, plants do not root in the red peat. Humidity Only a few readings were taken with some evaporimeters belonging to the Carnegie Institution and loaned by LivrncsTon. The total evaporation for seven weeks was as follows: under tamaracks in sphagnum, 275 cc.; on floating sedge, 321.7 cc.; in an adjacent oak-hickory grove, 860 cc.; in an open field border- ing the lake, 1056 cc. The last figure is short two days because the instrument was broken. These data, however, give conditions only near the surface, and are of value only in a study of germi- nation in the different zones. It has been pointed out recently (21) that great variations are found in short distances above the surface in the amount of water lost by evaporimeters. A lack of instruments made it impossible to study this phase of the subject. Light Light readings were made with the usual form of photometer. It was found that the light falling upon the tallest plants in all zones was approximately the same. Great differences were found between these values and those light values found at the surface in the different zones. With light value in the open as 1, the following values were found: under Chamaedaphne, 0.0026; under tamaracks, 0.033; under brambles found in a clearing society where maple and cherry seedlings were found in large numbers and some few individuals of each had reached a height equal to the brambles, the light was only 0.00022; among the leaves of the brambles it was 0.166. The value 0.033 seems to be the minimum light requirement for Chamaedaphne in the region about Ann Arbor. Fig. 8 shows dead Chamaedaphne at First Sister Lake where the light value was 0.033. The data recorded above show that the bogs of southern Michi- gan are for the most part not xerophytic habitats, but by far the largest areas are either hydrophytic or mesophytic. Only two or perhaps three of the zones can be considered as xerophytic habitats; $22 BOTANICAL GAZETTE [AUGUST the two are bog shrub and tamarack. To these might be added, depending upon its width chiefly, the bog sedge. This conclusion is justified both by a study of the vegetation and the physical conditions. It is believed that the data furnished at least point strongly toward the supposition that these zones are today xero- phytic habitats, even though they also prove that these same areas cannot long remain so. Numerous attempts have been made to explain the xerophytic structures in the plants found in these zones, but only slight reference need be made to them in this paper. Some have regarded the peat bog as a hydrophytic habitat. Thus WuitForD, after adding to other factors that of ‘insufficient aeration of the soil which prevents a healthy growth of the root system of land plants and also bars the presence of nitrifying bacteria,’ says that ‘‘these probably bring about xerophytic structures of plants so commonly seen in hydrophytic habitats.”’ He quite correctly regarded the bog chiefly as a hydrophytic habitat. In the area in which he worked also the true bog plants were not as limited in their distribution as in southern Michigan. It is quite probable that other conditions would enter into a detailed study of bogs in the northern part of the state (20). CLEMENTS (6) feels “‘that the current explanation of xerophy- tic bog plants, etc., is probably wrong, and that the discrepancy between the nature of the habitat and the structure of the plant is to be explained by the persistence of a fixed ancestral type.”’ SCHIMPER (15) attributes the xerophytic structures to the presence of humus acids in peat which impede absorption. Liv- INGSTON (12) has shown that any effect produced by humus acids must be chemical, as ‘‘bog waters do not have an appreciable higher concentration of dissolved substances than do the streams and lakes of the same region.” NILtson attributes differences in structure between swamp and bog plants to a difference in food supply, but this will not hold in this area. TRANSEAU believes from his observations and experiments that “‘in so far as southern Michigan is concerned (18, p. 36), the substratum temperatures prevailing in bog areas do not seem to be adequate to account for the presence or absence of bog plants tort] BURNS—HURON RIVER VALLEY 123 or their xerophilous structures. Experiments suggest, however, that farther north this factor is of prime importance’’; again, on page 37, ‘‘an examination of all physical and chemical data now available fails to account for the differences in the flora of the bog and swamp areas of this region. The most important factor is believed to be the physiographic history. Where the habitat dates back to Pleistocene times and has remained undisturbed, we find today the bog flora. Where the habitat is of recent origin or has been recently disturbed, we find the swamp flora, or a mixture of bog and swamp species.”’ DacuHNowskI (7, 8) believes from his experimental work that the condition which gives rise to xerophily and to zonation in bog plants “lies rather in the toxicity of the soil substratum, that is, in the production of unfavorable soil conditions brought about by the plants themselves.’’ This author further says that “if water transpired is replaced by bog water,” which would be the case to a limited extent during the summer when the water table was low and conditions for transpiration excellent, “‘the soils become more toxic.’ That is, the first effect of lowering the water table would tend to make the habitat more xerophytic. Further, ‘‘decrease in toxicity always follows aeration of the soil and drainage’’; that is, an increased lowering of the water table admits oxygen, decreasing the toxicity of the soil and making the habitat less xerophytic. With this is also associated an addition of humus which increases the capacity of the soil “for the adsorp- tion and retention of the toxins.” If the results obtained by DACHNOWSKI are correctly explained by him as due to bog toxins, they do not conflict with the data recorded in this paper. It is to be hoped, however, that his studies will be pushed farther. Davis, as has been pointed out earlier in this paper, believes that the bog is a xerophytic habitat, due to the drying of surface layers and the ability of peat to hold large amounts of water which are not available for the plants. The data given in this paper are in accordance with this view, and it appears to the author to more nearly cover conditions than any of the other theories advanced. It is not contradictory to the experimental work of the authors cited; this has been shown in the case of the work of DACHNOWSKI. 124 BOTANICAL GAZETTE [AUGUST TRANSEAU suggested that in the regions farther north the tem- perature of the soil may be of prime importance. Temperature readings in deeper layers in the bogs of southern Michigan than those which he discusses, and yet not too deep for the root sys- tems, resemble those of northern areas, and it is probable, in the light of his experiments, that they may be a controlling factor, even in those of southern Michigan. Yapp (21), in his excellent paper dealing with the relation of marsh flora to evaporation, has shown that great variation exists in the amount of water that is evaporated by instruments placed at different heights above the surface. Hence two plants may grow side by side and yet not be under identical conditions. He produces a large amount of data, especially concerning factors affecting the aerial parts of plants. He concludes that “any argu- ment drawn from mere proximity of position, without reference to the varying physiological problems of the different species, is entirely insufficient,’ and that “the arguments of authors, who insist that the so-called xerophytic structures of marsh plants can have no reference to present-day conditions, because both xerophytic and non-xerophytic Bp often grow side by side in nature, are entirely inconclusive.” Summary 1. The bogs around Ann Arbor are not xerophytic habitats, as such, but contain xerophytic, hydrophytic, and even mesophy- tic areas. 2. A study of the conditions in those areas which now are xerophytic indicates clearly that xerophytic conditions in bogs of southern Michigan will shortly disappear. 3. The presence of definite groups of plants in each zone is due chiefly to soil conditions found in that zone; also to position of the water table and secondary changes dependent thereon, as aeration, temperature, composition of the peat, etc. 4. The absence of certain plants from certain zones is due to decrease in the amount of light. Chamaedaphne apparently 1s not able to grow in this area in a light of 0.033. UNIVERSITY OF VERMONT BURLINGTON, VT. rg1t] BURNS—HURON RIVER VALLEY 125 NOH 507. 1905. 3- LITERATURE CITED . Bastin and Davis, Peat deposits of Maine. U.S. Geol. Surv., Bull. 376. aah uRNS, G. P., An exploration of a peat-forming lake. Science N.S. 21: , Formation of peat in Dead Lake. Rept. Mich. Acad. Sci. 6:76. 1904. , Botanical survey of the Huron River Valley. VII. Bor. GAZETTE 47:445. 1 a a aI 16. , Edaphic conditions in local peat bogs. Science N.S. 29:269. Igo9Q. . CLEMENTS, F. E., Research methods in ecology, p. 105. Lincoln (Neb.). 1905 . DacunowskI1, A., The toxic property of bog water and bog soil. Bor. 08. AZETTE 46:130. 190 , Bog toxins and their effects upon soils. Bor. GAZETTE 47:389. 1909. Davis, C. be Ecology of peat formation in Michigan. State Geol. Surv. 1906, p. . Frtu ae Se Die Moore der Schweiz, p. 129. Bern. 1904. . GANonc, W. F., Upon the raised peat bogs in the aries of New Bruns- wick. Trans. Ray: Soc. Canada II. 1114:131. 1897-189 . Lrvrincston, B. E., Physiological properties of bog water. Wok GAZETTE 39:348. 1905; other papers are cited here. . Pennincton, L. H., Plant distribution at Mud Lake. Rept. Mich. Acad. Sci. 8:54. 1906. Abii: Epira E., ae distribution at a small bog. Rept. Mich. cad. Sci. '7:126. 19 ee ER, A. F. W. Cae auf physiologischen Grundlage. 1808. Suaw, C. H., The development of vegetation in the ae depressions of the viceaty of Woods Hole. Bor. GAZETTE 33: 449. . TrRanseau, E. N., On the geographical distribution ee odal eal tions of the bog shant societies of northern North America. Bor. GazE 36: 401. 1903. , The bogs and bog flora of the Huron River Valley. Bot. GAZETTE 40: 3st. 1905; 41:17. 1906. ARRINGTON, R. " Phjsicdl properties of soils, p. 63. Ig00. WuitForp, H. N., The genetic development of the forests of northern Michigan. Bot. GAZETTE 31:314. 1901. App, R. H., On the stratification of a marsh, and its relation to evapo- ration and Lumpecabite. Annals of Botany 23:275. 1909. THE VEGETATION OF CRANBERRY ISLAND (OHIO) AND ITS RELATIONS TO THE SUBSTRATUM, TEMPERATURE, AND EVAPORATION. II ALFRED DACHNOWSKI (WITH ONE FIGURE) The atmospheric influences as ecological conditions for growth Various theories have been suggested to account for the presence and the relative persistence of this northern boreal flora under present climatic conditions. Some of these theories have been referred to earlier in the paper. Although widely separated from the central region of active bog formation with which the local bog is now only historically connected, its persistence and exist- ence in spite of the climatic changes and animal and plant migra- tion and invasion since the last glacial period, and the fact also that many peat deposits are reported to occur beyond the margin of the Wisconsin ice sheet, suggest that the most significant ecological factors are not to be looked for in the continuation of limiting conditions similar to those which prevailed when a colder climate existed than at present. That bog plants are related functionally as well as morphologically, and that they are grouped and localized with reference to more or less definite con- ditions of their environment is now a fact no longer questioned. It is also well known that no formation or plant society is likely to be relatively permanent and stationary, for there are changes constantly taking place in the environment as well as among the dominant plants and their associates. In the bog, however, but few successions of plants are in evidence, and the treatment of the vegetational societies from the standpoint of floristics and succession is therefore relatively free from complications. On the other hand, the determination of the factors in bog habitats, and the more detailed study of the dynamics of the process, that is, how some factors are related, their influence and duration— this phase of the problem is still in a state of uncertainty, and the methods of study have been all but satisfactory. When one con- Botanical Gazette, vol. 52] [126 1911] DACHNOWSKI—CRANBERRY ISLAND 127 siders the bog as a habitat, the various causative and limiting factors entering into the plant environment are not so readily distinguished. In connection, therefore, with the analysis of the life conditions in bogs, associated also with the distribution of bog plants, and their conflict with species whose range is more southern, certain meteorological phenomena have been added below. CLIMATIC CONDITIONS One of the main objects kept in view during the progress of the investigation on the ecology of Buckeye Lake, and one which seemed to the writer an indispensable preface to both the field and the laboratory study, has been the climate of the region. The general statistics were taken from’ Bulletin Q of the U.S. Weather Bureau Service (17), and from manuscript to which access was had by the courtesy of Section Director Hays of the Columbus (Ohio) Weather Bureau. No continuous series of climatological records have been made on Cranberry Island. The writer made records extending over the period of investigation; these records were supplemented by Mr. DickEy, whose readings were taken each time the evaporation of the bog habitat was measured. It is felt that the comparative climate statistics given below are generalized data which do not lend themselves to investigation in physiological ecology. Though facing the same set of climatic factors, few of the species forming the flora of the bog island con- front the same physiological problems, and hence any conclusions drawn from mere climatic data, without reference to the varying functional responses of the different species of plants, are certainly inadequate. However, the study of the meteorological observa- tions is suggestive mainly in ascertaining the essential differences between the local region and the conditions found in the northern center of bog formation, and in estimating the average tempera- ture and humidity exposure of the plants. The data given in table IV are for Columbus, Ohio; for Ann Arbor, Michigan, where bogs and swamp-lands are found more abundantly; and for Mar- quette, Michigan, where this type of vegetation reaches a still higher development. 128 BOTANICAL GAZETTE [AUGUST TABLE IV GENERAL METEOROLOGICAL CONDITIONS : rquette, Columbus, Ohio = —— PRC VATION ts 745 ee os ve a Sa 774 ft 930 ft 668 ft ae op WG an ee 3I yrs. 25 yrs. 33 yrs. Mean seantad temperature in degrees F. Re as See See eran ede rae 31 26 19 oh i sy POS as vee ce) 51 46 37 De hs a a 73 7° 63 WAL se ae es ee es See 54 51 45 ual te eee ee ec reese 2 48 41 Apsonite mami. 6 sao Cee. ees 104 Io 108 Aleonice MINN oo oa, oe eS hk —20 —24 we RBUINLE TONRG. eck eg foes 124 125 135 Greatest annual ones OSS Se ae Bests alae) 118 124 Lease aiiistranee 2 ea 89 97 Frost, aver. date Of last in spring Secs April 16 April 28 May 15 Frost, aver. date of first = ~ SA, 6.65 Oct. 16 Oct. 9 | Oct. 2 ] sagen in growin, ig Season. .......... 176 157 140 Me see sonal pr saiaiea toon inches tee Pe US OPEC ES Poke OS 8.9 6.6 6.1 te se a ee Bie) a0 7-3 IRINEE et eS eco. kegs oes 10:3 10.1 9-4 Me as 4 aan fags: 8 76 9.6 PUA OR ia es 5 eas Oe yawns os 37.2 32.2 32-4 depeOIMbe TASHA. 2 6 ois ee cs 51.2 47.7 42.9 Atsolise minim ) 6. i ek 26.4 21.1 25-3 Mean annual relative humidity.......... 79 79 80 ING. Says OrecInItAtION. «0/0. 00. 0 ce 144 138 161 Aver. direction of prevailing wind. . ies S.W. S.W. -W. Aver. minimum wind velocity. .......... eee 46 miles From the data in table IV, it will be observed that the seasonal and annual temperature decreases as one travels from the southern limit toward the northern center of bog vegetation. The climate of the region about Columbus is characterized by a milder winter but a relatively hot summer. The annual range in temperature is comparatively smaller than at Marquette, 102° F. as against 112° F. The normal annual range is here only between 96° F. (35°5 C.) and —6° F. (—21°11 C.), and the greatest departure from the normal variation does not exceed 16° F. The monthly averages for only two months are at Columbus below 32° F. (0° C.), as against five months for Marquette. The normal number of days per annum with a temperature above 43° F. (6° C.), the factor upon which ScumpER (29) and Merriam (27) base the boreal limit, is at Columbus approximately 185, that is about one-half of the year, as against 122 days at Marquette. The r9tt] DACHNOWSKI—CRANBERRY ISLAND 129 normal sum total of effective daily temperatures above 43° F. (6° C.), the estimate for which is derived by multiplying the mean average monthly minimum temperature of that period by the num- ber of days, is 10414° F. (2520° C.), as against 6466° F. (1422° C.) for Marquette. The normal mean temperature of the six consecu- tive hottest weeks of the year, effective also in determining the austral limit of species, is 75°. The warmest month is July with an average monthly maximum of 86° F. (30° C.), as contrasted with 77° F. (25°C.) at Marquette. The coldest months are Jan- uary and February with an average monthly minimum of 22° F. and 23° F. (5° and 5°5 C.) respectively, as contrasted with 10° F. and g° F. (12°5 and 12°o C.) respectively for Marquette. The dates of the latest killing frost in spring and the earliest in autumn, although not the exact limits of physiological activity in plants, or the limits of the growing period of most plants, are neverthe- less an unquestionably important factor. Six months of the year are normally free from frost about Columbus. Though the relation between rainfall and the amount of water needed by plants is of great importance in regard to differences in vegetation, the rainfall and its distribution during the seasons, and the number of rainy days, are of greater significance than is the amount of rain. At Columbus precipitation is quite evenly distributed, reaching an optimum of 10.5 inches (26 cm.) during spring and summer, when the vegetative functions of bog plants are more active, with a minimum of 8.5 inches (21 cm.) during the season of low temperature and in the quiescent period of plants. Columbus exceeds the annual precipitation at Marquette by 4.7 inches (11.8 cm.); the average number of days with rain- fall during the year, however, is considerably less than in northern Michigan, 144 days as against 161 days. In the north the greater precipitation is in the form of snow. Marquette has over five times more snow than Columbus, 125.7 inches (315 cm.), as con- trasted with 23.5 inches (59 cm.) here. In this vicinity the longer growing season of the plants has therefore correspondingly more of the precipitation available. On account of the higher temperature more moisture is needed, and hence the evaporation also is much greater here than at Marquette. Cold air does 130 BOTANICAL GAZETTE [AUGUST not take up so much water as does hot air; consequently the addi- } tional amount of water which the atmosphere is capable of taking -up to become saturated, that is, the evaporating power of the air, is greater here than at Marquette. The amount of evaporation also depends upon several other factors and conditions; the values of these will be taken into consideration below. Where evapora- tion is nearly as great as precipitation, the seasonal distribution of rainfall and humidity is a matter of greatest importance, for it is known that scanty rainfall throughout the year, or relative dryness of air and soil during the growing season, favors the devel- opment of xerophytic forms in almost any region. The relative humidity of Columbus and vicinity is only slightly less when compared with the north, the percentage of saturation ranging from 79 to 80 respectively. The distribution varies during the year only to a small extent between the month of least and that of greatest normal humidity. The rate of movement of air currents is, no doubt, of great importance to vegetation, not only because of the direct mechani- ‘cal effect and the indirect physiological action in increasing the evaporating power of the air, but also because transpiration increases with the velocity of the wind. That wind is an eco- logical factor of the greatest importance has been emphasized by many authors. KratmaAn and Warminc regard xerophytic structures in plants as acquired and necessary, on account of strong drying winds in exposed places. Even humid atmosphere when continually renewed leads to strong transpiration, and the danger may be decreased only as protection is provided either through density and height of species, or admixture of a variety of species in a community of plants. The average maximum velocity of wind does not vary greatly between Columbus and Marquette, and hence the influence of wind, though considerable in more exposed places, has apparently little relation to the differences to be accounted for in the character of the local vegetation. Briefly summarized, the region about Columbus and Buckeye Lake is characterized by a longer growing period with a relatively higher sum total of temperature exposure, a milder winter with normally slight variations, well distributed rainfall, and a relatively Tori] DACHNOWSKI—CRANBERRY ISLAND I31 high percentage of atmospheric humidity. The local climate is therefore preeminently a deciduous forest climate. The whole region was in its recent primitive condition densely forested. On the other hand, the marked increase of bog development in area and in variety of species in northern localities seems to be corre- lated with a decline in extremes of summer temperatures and an increase in relative humidity. The general effect is to produce a balanced functional relation, though limited in range, between the amounts of water absorbed and transpired. This phenomenon associated with bog habitats will be discussed in connection with a further analysis of the life conditions obtained in bogs from the point of view of their physiological aridity. If we take the above mentioned climatic factors into account in the interpretation of local bog conditions, it will be seen that meteorological data in this region are not such as to produce or account for xerophily or for persistence of bog floras. The climatic changes by which a region varies, if severe and varying between wide diurnal and seasonal changes in temperature, humid- ity, and light, entail naturally modifications in the functions and in the composition of a flora. The vegetation would be tested to the limits of its power of adjustment and acclimatization, and only the forms which had a greater efficiency of responses and had powers of resistance intensified to a new place-function would take up the habitat to the extent in which survival under the modified conditions would be possible. It has been pointed out above that changes in the flora are now occurring and have occurred during the development of the bog island. Many of the former plants have disappeared and are no longer to be found here, while others have survived, hold tenaciously the area under control, and are still constituents of the present flora. Their preservation in this region would seem to be dependent upon less obvious factors than climate. Functional habitat relations, as well as such ecologi- cal life relations as are comprised in association, in ecesis, and succession, need therefore the more detailed investigation. In determining these the first component to be considered is the réle of low substratum temperature. The temperature of a soil is a phytogeographical factor of great significance, but its weightiest 132 BOTANICAL GAZETTE [AUGUST importance is in its effect upon the functional activities of roots and rhizomes. Recently the temperature of soils and its fluctu- ations have received considerable attention. The relationship, however, and the general effect upon plant forms and the corre- lated functioning are nevertheless but little understood. This circumstance is perhaps the more to be regretted, since, broadly speaking, it seems that the relationship to plant life is the more favorable the more dominating the influence of the physical char- acters of the soil and particularly the relations prevailing in regard to the physiological water content and efficient temperature. THE ROLE OF SUBSTRATUM TEMPERATURE IN BOG HABITATS During the first few months of field work the device chosen for obtaining the substratum temperatures was the ‘“thermophone.” The apparatus is based upon the principle that the resistance of an electric conductor changes with its temperature. In obtaining the temperature of peat soils at various depths, the coils were sunk to the required depth, and their leading wires were then con- nected with the respective binding posts of the indicator box. A buzzing sound in the telephone increases or diminishes accord- ing to the position of the pointer while receding from or approach- ing to a section of the graded dial. Hence the position is soon found where the telephone is silent. This point indicates the temperature of the sunken soil. The instrument is very sensi- tive, but very inconvenient for obtaining weekly and monthly minimum and maximum temperatures. Later in the season the investigations were planned for a set of thermographs such as MacDoveat described (25), that would make a continuous record of the temperatures at any desired depth. The lack of sufficient funds and the failure to secure similar instruments made it neces- sary to resort to a conventional though less graphic method of measuring the temperature exposure of plants. In the field work of 1908, 1909, and at present, mercurial minimum and maximum thermometers were therefore used. The thermometers for the deeper peat strata were fastened to wooden poles and pushed down into the soil to the depth of 5 feet (1.5 m.). They remained in the soil during the period of investigation except for such short rg1t] DACHNOWSKI—CRANBERRY ISLAND 133 periods of time as were necessary to make a reading. For strata nearer the surface differential and ordinary mercurial thermome- ters were used, the bulbs of which were pushed down into the peat around the rhizomes of the plants to a depth of one foot (20 cm.) and three inches (7.5 cm.), respectively. The glass stems of the exposed instruments remained shaded from the direct rays of light. The temperatures recorded below, in centigrade, were generally taken on afternoons, usually between 12 and 2 P.M. It should be kept in mind that the maple-alder zone conditions correspond very nearly to those of the tamarack-willow-poplar zone of the northern bogs and swamps, and that a similar relation exists between the local central zone and the open bog-sedge zone of northern bogs. The readings taken during the period of observation are too voluminous for a tabulated record. Only those of the seasons of 1909 will be given in this place (table V). TABLE V TEMPERATURES (C.) IN THE PEAT SUBSTRATUM OF CRANBERRY ISLAND SEASON OF I909 : ‘ Aug. | Sept.| Oct. | Nov.| Dec. Station ee ee ee Central (sphagnum- cranberry) zone: Art. ¢ic 6.5 {5 tA 124. 6|24° (20> (94 es 487 F-54365 Air 36 cin 5 Ors 14.5 th (og 195. 20 ee 8 a7 7 ae 25 Al 7. ¢ Om... 32. 1.0 (425 [84.5122 (26° 20 jaesSiz6 127.517 ita | 25S bol 7 Scan. O.8 10.5 Tre 1s ee Sit. Seek aS S27git0 1 fF ) O.§ Soil 30 cm. O.5:19,051 7. 130. Ste2 iat Ol2a 2125. 129.5117 8 2,5 ES SO 7.5 (6.3 | 8.5| 9 |x |16.0j21 |22 |22.5/21.5|16.5|13.0 Maple-alder zone: OS 6 On O15. 12 tt |xt (136 120° (20.522 (20 [14 | 8 SO 30 Mii. 1.5 12.0 |) o.5ix ta [tO 819% (27. 5/20: 135-5 5 OOH Fb Mi. 6.5 |§.0.| 8.0|/10.5|14 |17.5]/10.5/21.5/21 [19 |15.5/14 Lake zone: ‘Water 7.6 cm... 23. C5 ir 13.5|14.5|20.5|26 |29 |28.5/25 |15 |6.5 | 3.5 Water 30 cm....... 1.5 |0.5 |13.5)14. 5/2 G lag. (28 -bias 11s 16.5 1 4 Water ¢.9 m:... 1.1 |2.7 |t3 |13.8|18.8|22.5/26 |26 |24 |12 |6.5| 5 A glance at table V shows that the temperature conditions, though comparatively uniform and high throughout the bog island, range somewhat lower in the maple-alder zone than in the central 134 BOTANICAL GAZETTE [AUGUST zone. There is a large daily as well as annual range in tempera- ture, but the range is considerably less in the soil than in the air above. The data obtained are sufficient to strengthen the obser- vation made, that in the spring the ice in the central zone melts with greater rapidity, and that a higher temperature results from the greater insolation and the increased absorption and retention of heat rays. On days following a sudden lowering of the air temperature, and also on cloudy days, the temperature of the surface bog water and bog soil in the sphagnum-covered area stands above that of the maple-alder zone. This gain in tempera- ture is cumulative and aids in the penetration of heat rays below the surface. The heat supply is obviously the most direct factor contributing to the substratum temperature, for the variations are associated directly with the amount and intensity of sunshine. The extreme slowness in the maple-alder zone is explained partly by the low conductivity of the partially decayed peat and the lack of a free circulation of air above the soil, but largely by the increas- ing diffusion of light rays due to the leafing out of trees and shrubs. Another point of interest is the fact that notable differences are found between the temperatures of the bog island and the surrounding lake water. When we compare the effects of gain and loss of heat between the free water surface of the lake and that of the peat area clothed with vegetation, it will be seen that the temperature of the central and the maple-alder zone remains higher than that of the lake during the autumn and winter months, and that during spring and summer the lake water is warmer at the respective (1.5 m.) depths than the peat substratum. Water has a specific heat far greater than any soil; it retains its heat longer and for this reason is warmer than the peat substratum in spring and summer. On the other hand, peat and humus are cooled more rapidly at the surface by the evaporation of water during the warm days of the seasons. The values of both heat conduc- tivity and diffusion are in general lower in peat than in water, and hence a rapid loss of temperature in the peat strata below the surface vegetation is thus prevented. A high temperature phenomenon existing in certain places is worthy of special mention. Not infrequently small sheltered 1911] DACHNOWSKI—CRANBERRY ISLAND 135 areas are found in the central zone bordering the Rhus-Alnus thickets where ice never forms in winter. Such temperature conditions would not attract special attention were it not for the fact that usually the temperature is so much lower in the adjacent areas. From a biological standpoint this fact is significant because these conditions favor isolation of habitats and produce a promi- nent floristic difference. Wolfella floridana commonly occurs in these “‘warm”’ pools. Plants are not dependent so ‘memeh upon the mean annual tem- peratures as upon the minima and maxima of temperature encoun- tered, and upon the duration of the vegetation season. To throw some light on the characteristic temperature range occurring throughout the year and within a growing season, the temperature data of the monthly extremes for the seasons of 1908, 1909, and for the autumn and winter of 1907, and the spring of 1910 are appended. As far as the writer is aware, no observations of minima and maxima temperature records within a bog, covering a period of three years, have been carried out thus far. On account of the fact that the present data were obtained at a station whose ecological significance is especially interesting, table VI of the temperature data is deemed worthy of a closer consideration. We see again that the temperature of the substrata at the differ- ent levels is affected less by the alternate heating and cooling at the surface, but in a far greater degree by the progression of the seasons. It increases slowly during May, is stationary more or less during August and September, and begins to decrease fairly rapidly in November. The maximum temperature occurs in July and August, and the minimum temperature is registered in January for the central zone. That of the maple-alder zone occurs in February. Observations have shown that the lake freezes to a depth of 8-15 inches (20-37 cm.), while the bog is covered by ice to a thickness varying from 3 to 5 inches (7.5-12.5 cm.), except for a few places where ice never forms. Consequently, the strata in the bog area below the one-foot level (30 cm.) are well protected from lower temperatures and from sudden temperature changes. When the sun’s heat melts the ice and snow, the percolating water derived from the melting ice lowers the temperature of the deeper 136 BOTANICAL GAZETTE [AUGUST strata a few degrees in the early spring. The wave of temperature increase falls here slightly behind in March, but the upper strata are not prevented from rising in the meanwhile rapidly above the freezing point. Though of ecological importance as a protective cover during the winter months, and of significance as a bad con- ductor of heat and in decreasing fluctuations in temperature, the ice and snow do not, therefore, retard appreciably the beginning of favorable growth conditions. The maples and willows of the TABLE VI MINIMUM AND MAXIMUM TEMPERATURES IN THE CENTRAL ZONE AT CRANBERRY ISLAND, 1907 to 1910 Jan. | Feb. | Mar. | Apr. | May| June! July | Aug.| Sept. | Oct. | Nov. |@Dec.J Air: May. 5 a | Oe 4 25 27.2137 .6133.3135. 135 3° | 23-3 Leer 19.4|/—24.5|—8.8)—7.7| 0.5} 3.3] 8.3] 7.2/1 6\—5.5|—9.4|—21.6 Range 37-7| 39-5| 33-8| 34.9|31.1|30.0\26.7|27.8| 36.1! 35.5] 32.7) “40-6 1 ft.(0.3 m.) AX... <2 acta lee ley. ioe. gl 2g | 27-7| 33 9 MS ° rato G-Glio 78. |t7 ar. G4 f2.5; 8 2.5 Range .. ach atl 6 6.715 ro | 4.5 5 6.5 oil: 5 ft.(1.5 m.) EAR oa. cea) 6 ol Of 42.2112. 5117 [23 (26 | 22.5], 22 15-5 Min... 7.5) 3.0] 4 7.2| 9.5|14 |16 |22 | 20 | 18 | 16.5) 1 Range. Bo Gost S 5 woo a5 4 5) 4S GREATEST RANGE Air: max. 35; min. —24.5; range 59.5. Soil 1 ft. (0.3 m.): max. 27; min. 0; range 27. Soil 5 ft. (r.5 m.): max. 26; min. 3.9; range 22.1. bog island are in flower about 8 to 10 days later than those on the campus of the university. A persistence, however, in the peat substratum of the winter cold and ice through the summer months is not proved, at least in this region. The records taken at a depth of 5 feet (1.5 m.) below the surface vegetation show a variation in temperature between 3°9 C. and 26° C., ie., an annual range within 22° C. At this depth only the anaerobic bacterial bog flora is most active. The roots and rhizomes of bog plants do not penetrate beyond the depth of 2 feet (0.6 m.), and the roots of 1911] DACHNOWSKI—CRANBERRY ISLAND 137 maples still less. Plants imbedded in the peat at a depth of 1 foot (0.3 m.) are within ranges of temperature from o° C. to 27° C. The underground growth of the plants continues when the winter temperature in the substratum rises and reaches the gradient from 4 to 8° C. When these soil temperatures prevail during winter for a sufficient length of time, the different stems and buds shoot upward and develop leaves and lengthen their internodes rapidly in the warmer weather of spring. The absorbing organs at 3 inches (7.5 cm.) depth in the peat substratum encounter a mean average of 13°5 C. with an amplitude of more than 30°. In all cases, however, the range of temperature in the maple-alder zone is less than that of the central zone by a difference of at least 6°. These observations and facts disclosed as to the actual tempera- tures in the peat substratum of Cranberry Island, and the seasonal changes therein point to the following conclusions: 1. The soil temperature of two plant associations formed about the bog island are slightly different, and each association has its own characteristic temperature range. 2. Of the two plant associations in the bog area, the one more liable to extreme low temperatures in the spring and during the growing season is the maple-alder zone along the border of the lake, and not the more xerophytic central zone. 3. The substratum temperatures as phenomena of the local peat deposits are not favorable to the preservation of bog types, if low temperature is considered to be an edaphic criterion; in connection, therefore, with an analysis of the life conditions in this bog area low temperature is not a limiting factor. 4. A persistence of the winter cold and ice through the summer months is a point not proved either by observation or by register- ing instruments. The persistence of northern forms in this bog, therefore, has some other cause than low temperature of the sub- stratum. In arctic latitudes, no doubt the most significant factor in determining the character and the distribution of plants, as well as in the formation and preservation of humus material, is low temperature. In the latitudes of Ohio, temperature is not a factor in the process. Neither does the accumulation of humus finally bring about edaphic conditions ‘‘too cold and too acid.” 138 BOTANICAL GAZETTE [AUGUST 5. It is not low temperature that kills invading mesophytes, but the edaphic physiological aridity prevailing in the central zone, which decreases the absorption of water by roots at a time when transpiration and the growth of the plants demand a greater physiological soil-water content. 6. The topographical distribution of plants in the bog is also affected by relations in regard not to low temperatures, but to the uneven physiological water content and the physical condition in the peat substratum. THE DIFFERENCES BETWEEN AIR AND SOIL TEMPERATURES We proceed now to a brief consideration of the question whether _the differences between air temperature and that of the soil are sufficiently marked during the growing period to prove a factor in the selection of plants for bog areas. To show this relation, data on the corresponding minimum and maximum air temperatures for the period under investigation have been added to table VI. The records were taken from the Climatological Service of the U.S. Weather Bureau at Pataskala, some 35 miles (0.56 km.) distant from Buckeye Lake. They represent fairly nearly the conditions at Cranberry Island on the corresponding period. Additional data are found also in table VIII. Upon comparison it will be seen that during July and August, the months which proved most critical for the cultivated plants grown in the bog area for experimental purposes, the shoots of plants were in an atmosphere varying between 7° and 35° C., while the roots and rhizomes were at temperatures varying between 16° and 27° C., ie., within a range of temperature differences not less than 9° and not more than 19° C. For a growing season lasting from May 5 to October 1, the average date of the latest and earliest killing frost, the actual differences between the temperature of shoots and roots amounted to 34°5 and 21° C. for each of the absorbing and transpiring organs respectively in the central zone, i.e., within a range of 29° C. It is seen that rapid and passing changes of air temperatures and the occasional extremes do not affect the sub- stratum temperatures. Only average effects prevail and the 1911] DACHNOWSKI—CRANBERRY ISLAND 139 great periodic seasonal changes. In winter and in summer the minimum temperature of the peat substratum is considerably higher than that of the air. Consequently, the annual mean temperature of the soil greatly exceeds that of the air. The monthly and annual fluctuations of temperature affect the peat area to a depth of 2 m., but they are at no time greater or with a wider range than those of the air. At what depth the mean tem- perature would remain constant has not been determined. That the differences between the temperatures of the air and that of the substratum are not as great as is generally supposed, is a fact upon which it is needless to elaborate further. They cannot be looked upon as factors in bog development or in the characteristic xerophily of the sphagnum-covered area in this region, and hence neither the substratum temperature nor the differences between soil and air temperature are of sufficient importance to enter into the problem of bog flora, and zonation or ecesis and succession. The records show that on the basis of temperature as the initial factor the central zone conditions are somewhat more rigorous, and that these conditions are mitigated in the maple-alder zone; but it cannot be claimed that the differ- ences of the plant covering in the two zones are directly correlated with the differences of temperature. With no attempt to minimize its influence, it is evident that for a comparison of habitats, tem- perature, at least as a single physical factor, is a matter of very subordinate importance on which to establish a causal relation. Those factors acting in conjunction with it demand the greater emphasis. It is questioned, therefore, even for regions where bogs reach their optimum development, whether the coefficient of the differences between the soil and air temperatures is to be looked upon as having a greater value than here in the selection of plants for bog areas, or the production of xerophilous characters. Whether or not important correlations between the temperature differences and the transpiratory activities of bog and other plants may be expected, a study of the transpiration quantities will doubtless reveal. Work of this character is now in progress and will be published as soon as opportunity permits. I40 BOTANICAL GAZETTE [AUGUST THE ROLE OF THE EVAPORATING POWER OF AIR As a preliminary study to the transpiration value of bog plants and to the question also whether the xerophytism and the stunted growth so manifest on maples, poison sumach, and various other plants in the central zone is brought about by an excessive evapo- rating power of the air, quantitative measurements have been made by the volumetric method to determine the saturation deficiency of the air in three representative stations. is one of the most important factors of the meteoro- logical ‘efcle of a locality. To the student of agriculture and of plant physiology it is a problem the study of which aids in supply- ing much of the desired information on the growth of plants in irrigated and uncultivated fields. Hann (16), who studied evaporation chiefly from the point of view of the meteorologist, has pointed out that the amount of water which the atmosphere is capable of taking up to become saturated is one of the indices of the influence of climate. The highly important observations made by LIvINGsTON (21, 23) op ome the fact that the effect of an atmosphere of great wer y influences the geographical distribution of atastl, and through its local variations exerts an equally determining effect as a physiological and an ecological factor. The problem of evaporation has been but imperfectly appreciated, and though the bibliography of evaporation is extensiye (24), the correlation between the evapo- ration under different conditions has not been satisfactorily formulated. The evaporating power of the air is generally under- stood to comprise a resultant of temperature, humidity, and wind. But evaporation is very sensitive to soil as well as to air relations, and since a multitude of local factors may influence either of the two conditions, the amount of evaporation integrates the effect of numerous variables. Evaporation is a rather complex resultant, therefore, and in preparing for an investigation which has in view the measurement of the amount of evaporation in plant societies, it is important to keep in mind the several conditions entering into the problem. It is necessary to recognize that the essential details of the phenomenon of evaporation are different in the great variety of conditions, and require separate and special study ee ¢ 11 ror1| DACHNOWSKI—CRANBERRY ISLAND I4I appropriate to the peculiar conditions. To measure evaporation in a few places in this locality, and then to assign the results to the region as a whole, is a procedure not without its accompany- ing shortcomings. It was intended to overcome this difficulty partially by measuring the variation in evaporation of the vertical as well as the horizontal vapor pressure gradient in a larger number of stations, plotting the results, and drawing isothymes. By a summation of the evaporation, that of the whole area could be calculated with greater accuracy. The distance of Buckeye Lake from Columbus and the inconveniences as to available time have made it difficult to secure the required observations. However, the problem here dealt with does not concern itself with the devel- opment of a formulated expression of evaporation for this region. The purpose at present is to obtain quantitative data on the rate of evaporation, and thus to secure direct evidence as to the rela- tion of the observed evaporating power of the air and the nature of the vegetation. The more detailed study of the phenomenon as originally outlined is now in progress. The ordinary markets are not prepared to supply the well designed standardized self-registering instruments which have been devised to meet the needs of the Weather Bureau (26). For ecological purposes, an instrument is required which can be placed under conditions practically identical with those which the plants themselves endure. For this purpose a small atmome- ter partly buried in the soil is desirable. Dr. Forrest SHREVE of the Carnegie Desert Laboratory, Tucson, Arizona, courteously left at the disposal of the writer several porous cups of the type as described and used by Livincston (21). The instruments had been previously standardized with an atmometer at Tucson, and since they are similar to those sent out from the Desert Laboratory to various other stations in the United States, the readings obtained may be readily compared. There are certain objections to the porous cups as an instrument in the field study of habitat conditions. The inability of the cup to withstand frost makes it practically impossible to obtain readings for more than the growing period of seven months, and the fact that the instrument does not prevent the direct entrance of rain to the jar 142 BOTANICAL GAZETTE [AUGUST introduces an error which becomes very large as the time interval between the reading of the instruments and the length of time and the amount of precipitation increases. The instrument recently described by Yapp (34) and by LivrncsTon eliminates the error last mentioned, but some weighing method, when available, will probably be more exact than any, since it alone can be employed in the measurement of evaporation from ice, snow, and growing vegetation. Of the instruments on hand, one was established as a standard in an open lawn freely exposed to the sun and wind on the campus near the University Observatory. It was placed in a manner to obtain readings on the saturation deficiency of the air at a height of 15 cm. above the soil surface. The atmometer remained in the care of Professor H. C. Lorp and his assistant Mr. KENDRIG, to whom the writer expresses his warmest thanks for their helpful interest. The records were taken three times daily in connection with the climatological observations called for by the U.S. Weather Bureau Service, and consisted of the reading of the depth of water remaining in a graduated container. The instrument continued in operation from May 21 to September 17, when an accident resulted in the breaking of the graduated retainer. Within a few days the trouble had been remedied and the observations pro- ceeded until October 11, when the first heavy frost occurred. Another cup was placed in an open and exposed place in the cranberry-sphagnum (central) zone, under conditions similar to those of the standard instrument. It was installed May 14. With the exception of the period from June 11 to July 17, when the total for five weeks was recorded, the loss of water by evapora- tion was determined at intervals of one week by running in dis- tilled water from a graduate, thus restoring the original water level of the container. Records were obtained until August 21, when it was found that the atmometer had been disturbed. A week later it had disappeared entirely. No attempt was made to replace it by another. The third instrument stood in the shaded conditions of the maple-alder zone. It was placed near large-sized maples whose cover was relatively dense though open. The reading of this 1911] DACHNOWSKI—CRANBERRY ISLAND 143 instrument extended uninterruptedly to October 2. During the writer’s absence in Europe, the readings in the two plant zones were recorded by Mr. Dickey; they have since appeared in pub- lished form (12). It is not necessary to reproduce in detail the original observations for the entire period. A series of data from the observations made have been summarized here and the con- clusions stated. Following are the atmometer readings for the several habitats, together with the comparative evaporation expressed in percentage of the standard instrument (table VII). TABLE VII ATMOMETER READINGS FOR STATIONS ON CRANBERRY ISLAND AND THE UNIVERSITY CAMPUS Central, i i - . aple-alder : suse ae a s oo poe, ne Percent. diff. M — Percent. diff. zone May 28) 118-8 cc. OF CC. 81.6 90,5 66. 65.7 PP nets ccna ee I10.9 7a | 83 60.5 54-5 JUue 43.550 88.1 6354 60.5 27.5 ai .2 Fi “ns wrecks ending July tite een Ue Os 87 349.2 91.7 290.4 59.6 Tae oe July 24. 151.4 120.2 79.3 et 7.8 9.8 59.2 50.6 42.9 ee . BBO E conan alt tae 140.6 69.8 49.6 36:3 25:6 AGhs Ta eee 134.6 82.4 61:2 70.4 $2.5 Total evaporation... . .|1349.2 933-8 69.2 690.8 eee As was to be expected, by far the smaller part of the total evaporation on Cranberry Island occurred in the maple-alder zone. The annual evaporation within the maple-alder zone is now about three-fourths of that in the open central zone, that is, fully 25 per cent of the moisture is saved by shade-producing trees and shrubs. The evaporation within this zone is greatest in the season from October to May. The difference in evaporation between this zone and the central zone is then at a minimum, but later it follows closely the growth of the leaves in the early spring and their fall in autumn. The maximum difference occurs in June and July. As the seasons advance, the evaporating power of the air in the forested zone varies with precipitation. Wind 144 BOTANICAL GAZETTE [AUGUST and temperature are less effective, for as the leafing out of the trees proceeds, and the increased undergrowth also becomes effect- ive in shade and interference with air currents, the retention of the moisture in the air decreases the evaporation rate and the relative humidity is raised. It would be instructive to follow in more detail the effect of the various meteorological factors on evaporation. This effect can very well be seen if the more important factors like temperature, intensity and duration of light, precipitation, wind, soil, and vegetation are referred to individually. But the results are uncertain and suggest the desirability of preliminary investigations in artificially maintained conditions by laboratory methods. In a general way, however, the data show that the inner temperatures of the maple-alder zone are lowered and the temperature extremes moderated, but the extremes in summer temperature much more so than those of the winter. The range in temperature is therefore more affected than the absolute tempera- tures. The importance of shade producers does not consist alone in their effectiveness to reduce transpiration, but also in their inverse influence upon meteorological factors. The foregoing table also shows that the greater saturation deficiency was recorded for the station on the university campus. The relative evaporation in the three stations is according to the totals 1349.2 cc., 933.8 cc., and 690.8 cc., the corresponding ratios are 100, 69.2, and 51.2. These differences for the three stations remained fairly constant throughout. The fact that the evaporation rate for the central zone with its numerous xerophytes should be less than that for an area which supports mesophytic forest trees seems anomalous and surprising. Thus for the vege- tation on the university campus the furtherance of transpiration by the evaporating power of the air is during some periods approxi- mately two times greater than that on Cranberry Island. This clearly shows that the evaporating power of the air, though furnish- ing a very valuable criterion for the differentiation between great centers of plant distribution and for the differentiation of habitats, is not an important factor in controlling bog vegetation or deter- mining the character of it. With the data on hand, it is not difficult to see that the chief 145 DACHNOWSKI—CRANBERRY ISLAND Igtt] "JUN PrvpuLys 07 oded oydvaFojoyd aay y woOU 7 dxa oun], » ge" gz1 Lb06 ¥6°£9 "Tet" ***" Yoviodesd [vO], gI se zz Qz ce Le Sr gS" iz gi LE 61 gS Fr I'S Apnop ‘wag |'*'€ “Bny S$ of 61°o1 8 ze ve | Lel Bee Bee 2% Sz; gS L°Sz Wd 9g “2 -Bny a° Qi: S30r 96°6 8 rf te | LL Str 2S: EF 61 1g‘b 6° £z ‘208 QT ‘WZI |'"*% “Sny Soe S*rf 6b°z Sor $*ke £x | ooo te a Ve 6S 'Er | 006 v'S = |papnops Ays “WV 9 ‘c “Bny 0. Sree ee SY 21 OL 8°22 “SFr 1 60h S21 be. Se 16° cr "Wa 11S aay Sct gc. S- LVL acer wf S-gr | = ¥Q'9 WG aye Shr | ‘So*¥ ¥°o% 0s ‘WI |***r ‘Bny ti -Sties- gS 't £1 ie 8 99°1 v1 zz g 00° 9's ‘HV 9 |° 2 any ae gz. 47 £e-Or 4 S°O- Sof te] LPL eon SSP zz | gro “es ‘Wag |°*'1€ Af oI Lz £1°6 a EL SOF gt | +9'9 QI $e Ot.1: ort I‘gI ‘908 6-g ‘wer |' "rf Aint Li gz 99°1 $*gI Le 58° @ 00'0 $*g1 Lz $9 00°° gf ‘WV9Q |'"*1f Am iz Ge 5 76°61 8 es tz vO'rr gt LE Iz PE "11 ise “Wd 9 ‘ ‘29ST ‘“WZI a:S ge. S* 96°6 8 gz oz | +9'9 gi ge oz | og’? I've Ivajo Ays ‘wy 9 |**'of Aqnf asuvi = “xvul punoi3 osuvl = -*xeu ‘ul punoia asuvl =*xeul = ‘UTUL punoi3 Cur $1) (ur 0) (mo s'2) | xpos ‘aynjosqe hy ‘gynyosqe ‘gynjosqe bias F aut 278 smiendting, —| yl EP y| Co) stvendaog, | gg 22%44| e¢o) ambecuamy, | gal, | we | AT om | a uonviodeay uonviodeagq uorvsodea iy GNVIS[ AYAAINVAD “ANOZ WONOVHdS-AUMAAINVAD AHL NI LNAIGVAD NOILVAOaVAa TVOILATA, THA ATAVL 146 BOTANICAL GAZETTE [AUGUST external factor which exerts a direct influence on the evaporation at the bog island is the water area surrounding the island. Evapo- ration from the water surface and from the vegetation produces a vapor blanket, the action of which influences to a great extent the normal range of evaporation under the varying temperature conditions and consequently the rate of transpiration. The evaporation blanket is readily transported over the open central zone, its rate of movement and consequently the rate of evapo- ration varying particularly with the action of the wind. In the relatively forested maple-alder zone, however, the vapor blanket is more stationary and hence more uniform in its influence. This vapor blanket covers the locality to a definite height vertically. Studies on the phenomena of evaporation of water over lakes and reservoirs (3) have shown that the vapor pressure of the vertical gradient varies, beginning nearest the evaporating surface with a maximum, and rapidly diminishing within several feet above the evaporating surface, until it approximates to that in the free air. A few isolated readings confirmed this for the stations in question, as table VIII will show. At first the readings were taken every hour from 6 A.M. to 6 p.m.; later at intervals of six hours. For convenience, the larger time values covering the period from July 30 to August 3 are given here (fig. 8). The amounts are in the ratios too, 71, and 50 for positions at 5 feet (1.5 m.), 1 foot (0.3 m.), and 3 inches (7.5 cm.), respectively. Hence in general, the lower stratum of a vegetation has a smaller range in humidity variations and possesses an atmosphere usually much more humid than the upper vegetation stratum or the free air above the vegetation level. The data confirm the noteworthy results of the evaporation experiments by Yapp (34), and show that the bog vegetation at the lower levels is exposed to trans- piration conditions much less severe than those existing at posi- tions above the substratum and those quite clear of vegetation. But the growth of bog plants and their successful occupation of the habitat do not depend so much upon the total amount of evaporation or the time factor of this exposure, that is, the amount of moisture which the air contains during critical periods of the growing season. The functional activity of the plants is tg1t] DACHNOWSKI—CRANBERRY ISLAND 147 not one of relation to a single factor. In the interrelation of con- ditions, the real limiting factor to an increase in functional activity is not evaporation or temperature, but the toxicity of the sub- stratum. This fact reveals itself only in experimental tests. Toxicity comes markedly into play when the amount of water available for absorption has reached a stationary value, through Fic. 8.—Experiment station in the cranberry-sphagnum association; in the fore- ground stunted growth of Rhus Vernix; photographed July 31, roto. the activity of bacterial organisms and other processes. In the field it is very difficult at times to decide which features of the vegetation are to be correlated with low atmospheric humidity, which with variations in temperature and light conditions, or with other factors cooperating at the same time. It is obvious that each in its turn may play the part of a limiting factor, for growth and transpiration are very susceptible to variations in either of these conditions. But in the laboratory the extended experi- 148 BOTANICAL GAZETTE [AUGUST ments with cereals, legumes, and with plants from the various zones of the island have shown that most plants are unable to pro- vide for a balanced relation between the supply of physiological water which the bog substratum can furnish and the excess of water lost during transpiration even when the temperature or the evapo- rating power of the air are favorable for any length of time. The susceptibility of the plants to the presence of small traces of deleterious bacterial transformation products accumulating in the surface layers of the peat substratum has been demonstrated elsewhere. An intimate and controlling relation has been found to exist between soil bacteria and the plants growing in the central zone. This has shown itself by various physiological and chemical tests, and by the fact that the presence and fitness of bog plants in the central zone is due mainly to more efficient functional responses to physiological drought. The edaphic aridity prevail- ing in this zone decreases the absorption of water by the roots in wheat plants about 50-65 per cent, at a time when transpiration and the growth of the plants demand a greater physiological water content. The further quotation of definite examples must be post- poned. The ratio of the possible rate of water absorption to the rate of transpiration and growth becomes thus the real determin- ing factor in the bog habitat and in the selection and in the dis- tribution of plants. In all cases cultivated agricultural plants become flaccid and the roots appear gelatinous or as if burned black at the tips. The general dwarfing of roots (see illustrations in 7 and 8) offers very little efficiency to physiologically arid con- ditions; nor is the change in form characters of shoot and leaf induced by the consequent lack of coordination of functions an advantage or an adaptation. Resistance to desiccation and the capacity for conserving water are more direct and more efficient _ responses to the limiting condition which the plants meet. This fact is not necessarily to be taken as valid in accounting for all highly specialized and inheritable structures so frequently met with in plants occurring in these habitats. The alteration of shoots and leaves in response to the stimulation of external factors may or may not increase fitness to the conditions, but it is safe to assume that the capacity for physiological changes and responses Ig1t] DACHNOWSKI—CRANBERRY ISLAND 149 controls the survival value of plant forms to a greater extent than has been admitted. . aun p w ~JI 405. 1909 9 Onto STATE UNIVERSITY CoLuMBUs, OHIO LITERATURE CITED . Apams, C. C., The postglacial dispersal of the North American Biota. Biol. Bull. 9:53-71. 1905. ; Bastin, S. E., and Davis, C. A., Peat deposits of Maine. U.S. Geol. Survey, Bull. 376, p. 61. 1909 . BicELow, F. H., Studies on the phenomena of the evaporation of water over lakes and agers Monthly Weather Review, U.S. Dept. of Agriculture 36:437. . CHAMBERLIN, T. C., a Ssciaptes R. D., Geology. New York. 1906. . CLEMENTS, F. E., Reapixch methods in sede: Lincoln, Neb. 1905. Cow tes, H. C., Picdcuechie ecology of Chicago and vicinity. Bor. GAZETTE 31:73-182. 1905. - Dacunowskt, A., The toxic property of bog water and bog soil. Bot. GAZETTE 46:130-143. 1908. , Bog toxins and their effect upon soils. Bot. GAZETTE 47:389- ; Physoiericale arid habitats and drought-resistance in plants. Bor. GAZETTE 49:325-340. 1910. Davis, C. A., Contribution to the natural history of marl. Jour. Geology 8:485. 1900; ale, A pee, contribution to the natural history of marl. , Peat. Geological nS of Michigan. 19 - Dickey, M. G., Evaporation in a bog habitat. ” Ohio Naturalist 10: 00. . Frtu, J., and Scuréter, C., Die Moore der Schweiz mit Beriicksichti- rf. gung der gesammten Nocitiags: Geol. Komm. d. Schweiz. Natu Gesells. Bern. 190. - Gray, Asa, Adipose: before the American Association. Am. Jour. Sci. TIT. 4:293. 1872. - Gray, S. M., psa water supply for the city of Columbus. Ohio Report of 1 HANN, J., Fiatiitek of climatology. 190. - Henry, A. J., Climatology of the United States. Bull. Q, U.S. Dept. of Agtcitiars. Weather Bureau. 1 . JENNINGS, O. E., A botanical survey of S588 Isle, Erie County, Penn- sylvania. Ann. ‘Cunt Museum 5:289. 1 - Krutman, A. O., Pflanzenbiologische Staten aus Russisch-Lapland. Acta Soc. pro Pinus et Flora fennica 6:113. 1890. I50 BOTANICAL GAZETTE [AUGUST 20. Leverett, F., Glacial formations and drainage features of the Erie and Ohio basins. U.S. Geological Survey 41: 1902 21. Livrncston, B. E., The relation of desert plants to soil moisture and to evaporation. Carnegie Institution of Washington, Publ. 50. 1906. a. , Physiological properties of bog water. Bort. GAZETTE 39:348- 355. 1905. 3. , Evaporation and centers of plant distribution. Plant World II:106-112. 1908. 24. Livincston, Mrs. J. G., An annotated bibliography of evaporation. Monthly Weather Review, U.S. Dept. of Agriculture 36 and 37: 1908- 1909. 25. MacDoucat, D. T., Soil temperatures and iachischee, Monthly Weather Review, U. S. Dept. of Agriculture 31:375. 1903. 26. Marvin, C. F., Methods and apparatus for the a of evaporation. © Il. Monthly Weethes Review, U.S. Dept. of Agriculture 37:182-190. 1909. 27. Merriam, C. H., Life zones and crop zones of the United States. Divi- sion of Biological Survey, U.S. Dept. of Agriculture, Bull. 10:54. 1909. . SCHREINER, O., and ReeEp, H. S., The réle of ian in soil fertility. Bureau of Soils, U.S. Dept. Agric., Bull. 56. 19 29. Scuumprr, A. F. W., Pflanzengeographie auf si cashegioshie Grundlage. Gustav Fischer. Sema. 1808. 30. SCHWENDENER, S., Die Spaltéffnungen der Gramineen und Cyperaceen. Sitzungs. Preuss. Akad. Wiss. Berlin. 1889 31. Transeau, E. N., On the geographic distribution and ecological relations of the bog plant societies of North America. Bot. GAZETTE 36: 401-420. 1903 31a. , The bogs and bog flora of the Huron River Valley. Bot. GAZETTE 40:351-375, 418-448. 1905; 41: hg 1906. 32. WarmInG, E., Oecology of plants. Oxford. 19 33. Wricut, F. G., The glacial boundary in Ohio, an U.S. Geol. Surv., Bull. 58. 1890 34. Yarp, R. H., On stratification in the vegetation of a marsh, and its rela- tions to evaporation and temperature. Annals of Botany 23:275-320 1909. A BRIEFER ARTICLES IS OPHIOGLOSSUM PALMATUM ANOMALOUS? Under the unassuming title ‘‘Notes on the morphology of Ophio- glossum (Cheiroglossa) palmatum L.,’’ BowER" has presented a paper con- taining generalizations of an unexpectedly far-reaching kind. Inasmuch as many of the arguments in this paper are directed against a paragraph in a recent paper by the present writer,? it seems desirable to make a few statements calculated to clear up the situation. BoweEr’s account is based on two fertile specimens obtained during a visit to Jamaica, also on a reexamination of herbarium specimens. He adheres to his previous view of the morphology of the plant,3, 4 namely, that the several to many fertile spikes are derived by duplication or branching of the single spike found in O. vulgatum, in contrast to the usual view that the spikes represent fertile lobes of the leaf. Probably the most serious objection to the latter interpretation is the fact, brought out by Bower, that some specimens show one or more of the distal spikes inserted on the adaxial face of the leaf in a more or less median position, while one might expect to find them inserted marginally. Unfortunately neither of the specimens from Jamaica, and in fact no specimen which has been available for sectioning, shows this critical feature. BOWER recognizes the importance of this method. of study, for in a number of his figures he represents the vascular supply of fertile spikes. I wish to point out that each of the cases so represented (figs. 17, i-ix; 19, I-v; 20, i-vii) fits in with my interpretation of the fertile spike as either a single segment of the leaf or a fused pair of segments, so I must insist that until an opportunity occurs for demonstrating the origin of the vascular supply to the upper median spikes, my interpretation stands.. t the same time, I cheerfully admit the possibility of BowEr’s view as an alternative theory, especially on the basis of the branching of fertile spikes, figured in 1896 for O. pendulum as well as O. palmatum. Is it t Ann. Botany 25:277-208. pis. 22-24. 1911. “? The nature of the fertile spike in the Ophioglossaceae. Ann. Botany 24: 1-18. pls. 1, 2. 1910 3 Studies in the morphology of spore-producing members. II. Ophioglossaceae- London. 1896. 4 The origin of a land flora. London. 1908. 151] [Botanical Gazette, vol. 52 rs2 BOTANICAL GAZETTE [AUGUST not possible, as has turned out in so many other cases, that the truth lies between the two extreme views? May it not be that the spikes of O. palmatum represent lobes of the leaf, and that certain of the upper ones in strong growing plants have suffered splitting or duplication? Such a view would take into account the effects of the peculiar life habits of this species, and at the same time would explain the identity in origin of the lower spikes with that found in the other members of the genus. In his recent paper Bower supports his interpretation by eight con- siderations, two of which are referred to above. Under one heading he urges the fact that “the identity of the margins of the leaf, so far as these are defined by the vascular strands, is entirely merged by the repeated fusions of the strands on the adaxial face of the elongated petiole” (p. 289). Yet, while describing the insertion of the petiolar strands on the central cylinder of the stem, BowEr shows that the leaf gap is obscured by a vascular commissure stretching across the gap at the point of attachment of the leaf trace bundles, and this fact does not cause a doubt as to the existence of a leaf gap. Apparently the anastomosing of vascular strands is characteristic of the plant, and the relationships of the parts can be best interpreted by comparison with simpler members of the family; this is what I have sought to do. Professor BOwER’s caustic remarks concerning my paper on the Ophioglossaceae may the more readily be passed over in view of the fact that he has expressly repudiated his former view as to the relation- ships of the group, and hence accepts the main contention of my paper. _ With the candor characteristic of a true scientist, he has considered the evidence accumulated since 1896, and decides that the balance is in favor of allying the Ophioglossaceae with Filicales rather than with Lycopodiales. As a consequence of this, he regards the fertile spike not as a sporangiophore, but as one or more pinnae, here again agreeing with my conclusions. If now it is admitted that the fertile spike in most members of the group represents one pinna or a fused pair of pinnae, it is difficult for me to see why the interpretation should not be pushed to its logical end. The pinna nature of the fertile spike is most clearly seen in Botrychium; if the spike of O. vulgatum or O. reticulatum has a vascular supply which originates in a way similar to that of species of Botrychium, it may be regarded as representing two fused basal lobes of the leaf. The spike of O. pendulum has a similar vascular supply and may also be regarded as having the same morphological nature. A basal median spike in O. palmatum has a vascular supply identical with this; why then should it not be interpreted in the same way 1911] BRIEFER ARTICLES 153 Marginal spikes situated above this would then represent single lobes of the leaf, comparable to the abnormal spikes of B. obliguum figured in my paper. In fact, the new figures representing sections through the base of fertile spikes more than ever convince me that there is an under- lying unity in the family, in spite of the complications shown by O. palmatum. ‘This unity appears in my interpretation of the fertile spike, and forms the only basis so far offered for comparison of all the members of the group. Just what becomes of the order Ophioglossales remains slightly in doubt, for BowrR sometimes uses this term and sometimes the term Ophioglossaceae in his recent paper. Without entering into taxonomic considerations, it would appear that Ophioglossaceae might well remain a family of Filicales. In conclusion it may be remarked that BowEr’s admirable summing up of the differences in the vascular supply of spore-producing organs among the Psilotaceae, Sphenophyllaceae, and Ophioglossaceae lends support to the view that the two great phyla Lycopsida and Pteropsida have been separated for a vast period of time.—M. A. CHRYSLER, Uni- versity of Maine, Orono, Me. CRYPTOMERIA JAPONICA (WITH FOUR FIGURES) At the Harvard Botanic Garden, there is a Cryptomeria japonica 8-10 feet high. When examined early this spring, many of the branches that bore female cones were seen to have produced abnormal growths. The central axis of the cone had in some cases elongated into a vegetative branch. This condition has often been noted before in Pinus, Abies, Larix, Sciadopitys, and some other conifers, as well as in Cryptomeria. The Gardeners Chronicle’ in discussing proliferous cones says, ‘this condition is so common in our experience as to be nearly as frequently site with as the normal state.’ Then again in reference to Cryptomeria,® ‘“‘a very common peculiarity is the proliferation of the axis beyond the cone in the form of a slender branchlet.’”’ This vegetative proliferation has also been described by PENzIG,7 MASTERS,® EICHLER,’ and others. Another and apparently undescribed condition was observed in the 5 Gard. Chron., January 28, 1882, p. 112. 6 Ibid., November 30, rg0r, p. 380. 7 Pflanzen Teratologie, Vol. II, p. 509. § Vegetable teratology, p. 24 ® Excursions morphological, a Hist. Rev., April 1864. 154 BOTANICAL GAZETTE [AUGUST case of the tree at the Botanic Garden. It was found in certain instances that the proliferating axis, instead of being merely a leafy shoot, bore male cones. ‘This condition, so far as the writer has been able to observe, has not hitherto been described. Owing to repairs being made at the greenhouses, this tree had been placed horizontally in a dark pit for the winter. This unnatural condition perhaps accounted for the abnormal growths. Fics. 1-4 Figs. 1 and 2 show female cones bearing clusters of male cones on their elongated axes. Fig. 3 shows a normal cluster of male cones and another cluster on the proliferated female cone. Fig. 4 shows a normal female cone on the left, a female cone on the right bearing a vegetative branch, and a female cone in the center bearing a cluster of male cones.— ANSEL F. Hemenway, Harvard University. CURRENT LITERAPURE BOOK REVIEWS Plant pathology The growing interest in plant pathology is attested by the appearance recently of two new books and a journal dealing with this subject. Of the books, one, by STEvENS and Hatt, is the second to appear in the United States within a year. The other, also in English, is by MassEr.? The new journal appears under the name Phytopathology, as the official organ of the American Phytopathological Society. The book by STEVENS and HALt is written to meet the needs of those who are concerned with plant diseases from a practical standpoint, and who wish to identify diseases easily and quickly, and find definite directions for combatting them. In its general scheme it departs considerably from the usual treatment adopted in works on plant diseases. The method of treatment is such as seemed to the writers most serviceable for the end in view. The diseased plant is the important object under discussion. Technical details relating to structure and life histories of fungi are omitted. Characteristics of fungi are described only where the fungus itself is sufficiently conspicuous to form a distinguishing mark by which to recognize the disease, as in mildews. identify the disease described. In the same way life histories are discussed only in so far as is necessary for the understanding of certain diseases, as in the case of rusts, and then only in their general aspects. In general only such characteristics are mentioned as are obvious to the naked eye and will aid the practical man in identifying the diseases. This method of treatment has permitted an arrangement of the material in the body of the work b on the classification of host plants, instead of the usual arrangement according to the systematic sequence of the fungi. The book begins with brief introductory sections on general subjects of practical importance, such as fungicides, spraying machinery, cost and profits of spraying, and similar topics. This part is of special value to the practical man, as it brings together information regarding the newer spraying mixtures and methods of combatting diseases which have been published in various papers not easily available. A short chapter on general diseases takes up *STEVENS, F, L., and Hatt, J. G., Diseases of economic plants. 8vo. pp. x+513. jigs. 214. New Yo oe The Maccsilian Co. 1910. $2.00 ? MASSEE, GEORGE, Diseases of cultivated sie sad trees. 8vo. pp. xii+602. jigs. 171. New York: The Macmillan Co. 1910. $2.25. : 155 156 BOTANICAL GAZETTE [AUGUST such diseases as ‘‘damping off,’”’ which are not restricted to apr ser —— of plants. The rest of the book deals with “Special diseases of crops.” The material is arranged according to the agricultural classification of plants, under such heads as pomaceous fruits, drupaceous fruits, small fruits, vege- table and field crops, cereals, fiber plants, trees and timber, and ornamental plants. The descriptions are clear and concise, giving such characteristics as enable the general reader to identify the disease. The book is illustrated by numerous halftones, which, however, are only of fair quality. A feature peculiar to the book is the introduction of a unique popular nomenclature for the diseases described. This feature consists in the uniform construction of popular names, where none exist, by adding the ending -ose to the generic name of the organism causing the disease. Although this it becomes Simicnwe on account of the extent to which the idea is carried ously, and have only local but forceful eciledace. which cannot be attained by names manufactured on a wholesale scale. In this case their acceptance would rather lead to a confusing monotony. The k will be found extremely useful to those who have to do with the ih ine of plants. It will enable them readily to renew information on ise to them, and to identify new diseases not too obscure. Being aehacecaliy | arranged, the book itself serves as a sort of host index, making the finding of material an easy matter. In each case is given what is known of methods of treatment, the matter of real importance to the grower. The work of Masse is the outcome of the author’s well-known Text-book of plant diseases, the last revised edition of which appeared in 1903. The growth of plant pathology in the interval has made necessary a complete revision of the text, with the addition of so much new material that the result is a new book. While it follows the general plan of the older work, the treat- ment of the subject is much more extended, owing partly to the enlarged scope of the new book, but more directly to the amount of new material incor- The book begins with introductory sections discussing such general sub- jects as primary and secondary causes of disease, meee infection of plants, the dissemination of fungous diseases, injuries not due to fungi, and other related subjects. Space is also given to the potent of fungicides and spraying. The American reader will be struck by the absence from this section of a discussion of apparatus for the application of fungicides. The greater part of the book is taken up with descriptions of diseases and the fungi causing them. This part is arranged according to the groups of fungi, although none of the ordinary systems of classification are followed in detail. In the Pyrenomycetes, for example, the spore characters are taken 1911] CURRENT LITERATURE 157 as the primary basis for the arrangement, thus leading to an association of genera-entirely different from that usually found in taxonomic works. By this method of classification, the genera of the Hypocreales and Dothidiales are distributed among the Sphaeriales. In the descriptions both the charac- teristics of the diseases and the life histories and characteristics of the causal organisms are given. The scheme is similar to that followed in the author’s Text-book, but the accounts are much more complete as to detail | eases. The older and better known facts receive full and careful treatment, but with regard to the newer facts of plant pathology, the work shows a of critical consideration of the literature which greatly impairs its value as a reliable reference book. A few instances illustrating this point may be cited. The rotting of lettuce in greenhouses is still attributed to Botrytis cinerea (Sclerotinia Fuckeliana) (p. 263), although the investigations of SmrrH3 several years ago have shown that Sclerotinia Libertiana is the principal cause of this rot, while Botrytis-forms are only of secondary importance. These two fungi, although related, differ greatly in their mode of life, Botrytis being a common saprophyte everywhere, while S. Libertiana is a soil fungus. This great difference in the mode of life of the two fungi is of importance when methods of combatting them are considered. The wilt disease of cotton and other plants is described (p. 228) under Neocosmospora (misspelled Neocos- mopara in the page-heading, seach POE: and text, and still different in the index). A symptom of the same disease is described (p. 494) under its old name “Cotton Frenching,” caalid by Fusarium vasinfectum. The genetic relationship between these two fungi has been shown by SmirH.4 Spraying for peach leaf curl is regarded as of little value because the perennial mycelium of Exoascus deformans in the shoots produces a crop of diseased leaves each year in spite of spraying. As a matter of fact, there is no disease that can be controlled with more certainty and with more striking results by spraying than the peach leaf curl. Furthermore, the careful investigations of PreRCcES have shown that the origin of the spring infection is still obscure, but that probably the perennial mycelium in the branches has very little to do with the early infection. The common apple blotch fungus the author suggests 3SmiTH, Ratpu E., Botrytis ane Sclerotinia; their relation to certain plant dis- eases and to each other. Bot, GAZETTE 29:369-407. pls. 3. figs. 3. 1900. 4SmitH, ERwin F., Wilt disease of cotton, watermelon, and cowpea. U.S. Dept. Agric., Div. Veg. Physiol. and Path., Bull. 17. 1899. 5Prerce, NEWTON B., Peach leaf curl; its nature and treatment. U.S. Dept. ? Agric., Div. Veg. Physiol. and Path., Bull. 20. 1900. 158 BOTANICAL GAZETTE [AUGUST (p. 412) is a stage of the apple scab fungus, yet these fungi could scarcely be confounded by one who had seen them. Under the heading “Peach leaf blotch (Gloeosporium cydoniae Mont.),” this disease is said to cause spots on the “living leaves of the peach (Cydonia vulgaris).” Sphaeropsis malorum is described only as a leaf spot disease of the apple, although it has been longest and best known as the cause of the black rot of the fruit, and later as the cause of a serious bark canker of apple trees. The new journal Phytopathology is to be issued for the present as a bi- monthly publication of the American Phytopathological Society. The aim, as set forth in the editorial announcement, is “to provide a place for the publication of phytopathological papers which would otherwise be lost or scattered in various places.” While much of its space will be occupied by papers read before the society, it is the policy of the editors to make the journal more broadly representative and to open its pages to contri- butions of value from any source. It is of octavo size, containing at present about 35 pages of text and a number of plates in each issue. The halftone plates are of unusually good quality. The first issue is fittingly introduced by an excellent halftone portrait of DeBary, with a brief sketch of his life and of the influence of his great personality on the advancement of plant pathology. Heretofore the chief interest in plant pathology in the United States has been on its economic side, and this side has been highly developed as a result of the facilities for investigation, and for the ready means for publication of results having an economic bearing, offered by the experiment stations. As a result of the emphasis on the economic point of view, little attention has been given to the more fundamental problems relating to the subject. Such phases as the physiological relations between the host and parasite, the changes in metabolism brought about by the parasites, and the enzymatic activities of parasites, have remained almost uninvestigated. A journal like the present one, devoted entirely to the interests of plant pathology and not restricted to e purely economic phases of the subject, will undoubtedly do much to stimulate research in these deeper problems of plant pathology.—H. Has- SELBRING. Fossil plants The second volume of SEwarn’s Fossil plants’ has remained too long unnoticed by this journal. The first volume appeared in 1898, and the general purpose and method of the work were stated in the review published at that time? The thirteen years that have elapsed have been memorable ones in the history of paleobotany, so that if this second volume had appeared as Ee ialewe ls = C., Fossil plants; a text-book for students of botany and geo'ogy. Vol. II. pp. oi. figs. 265. ee sine The University Press; New York: G. FP. Pehiaie's oiee 1910. $5 7 Rev. in Bor. GAZETTE Pag 1898. ror] CURRENT LITERATURE 159 promptly as at first expected, it would have been sadly out of date by this time. So large an addition has been made to our knowledge of fossil plants, that now we are to have three volumes of this work, instead of two, and the third volume, promised to appear “with as little delay as possible,” is to contain the seed plants, and also a much-needed discussion of the geographical distribution of plants at different stages in the history of the earth. The present volume contains the pteridophytes, with the exception of Equisetales and the major part of Sphenophyllales, which were treated in the first volume. As has been said often in this journal, the material of paleo- botany must be traversed critically by morphologically trained paleobotanists, so that morphologists may be able to base their conclusions upon reasonably assured data. Even yet, most paleobotanists are stratigraphers, their chief concern being to be able to recognize a given horizon by a given form, what- ever its relationships may be. Of course, such paleobotanists are geologists rather than botanists. EWARD has now done this service for botanists in the very critical series of fossil pteridophytes, and we are able to put together two or three com- petent and independent judgments, feeling well assured if we find agreement, and feeling cautious if we find disagreement. It is impossible to discuss the details of such a book, for it is more a manual than a reading text. It will be sufficient to indicate the titles of the 16 chapters. XII, Sphenophyllales (continued) (16 pp.); XIII, Psilotales (13 = XIV, Lycopediales (62 pp.); XV, Aoooteaset Lycopodiales (104 pp.); XVI Sipillaria (31 pp.); XVIT Stigmaria (21 pp.); XVIII, Bothrodendreae fs pp.); XIX, Seed-bearing plants closely allied to members of the Lycopodiales (9 pp.); XX, Filicales (44 pp.); XXI, Fossil ferns (71 pp.); XXII, Marat- tiales (fossil) (17 pp.); XXIII, Psaronieae (15 pp.); XXIV, Ophioglossales (fossil) (5 pp.); XXV, Coenopterideae (91 pp.); XX VI, Hydropterideae and Sagenopteris (11 pp.); XXVII, Genera of Pteridosperms, ferns, and plantae incertae sedis (97 pp.). These titles do not indicate any coordination, but perhaps mage represent the legitimate state of mind in the presence of the material._—J. M. C. MINOR NOTICES New Zealand plants.—New Zealand is fortunate in having as its leading botanist one who has not only carefully studied the problems of plant life in a comparatively new region, but has now given to the general public a most interesting volume® on the vegetation of these islands. Beginning with a simple synopsis of the history of botanical explorations in New Zealand, from the work of Dr. Joun Forster in 1773 to the present day, Dr. CocKAYNE proceeds to discuss the most notable features of a vegetation ranging from a § Cockayne, L., New Zealand ee and their story. 8vo. vii+190. figs. 71. T910,. Wellington: Jobe Mackay, Government Printer. 160 BOTANICAL GAZETTE ' [auGusT rain forest of almost tropical luxuriance to xerophytic sand dunes. The i in botanists of other lands will find the little volume useful in imparting a picture of the vegetation of that distant country. For local use it cannot but be of the greatest service to teachers who are seeking an intelligent appreciation of their surroundings. e — of ber es opie are further recog- nized by a chapter on the cultivation o on the school grounds and in the school garden. The ei will te interested, among other things, in the considerable number of plants with juvenile and adult leaf orms. Waa of some of the most remarkable plants described.—GEo. FULLE. North American Flora..—Volume XXV, part 3, continues the treatment of the Geraniales and includes an elaboration of the Rutaceae and Surianaceae by Percy Witson, the Simaroubaceae by JonN KUNKEL SMAatt, and the Burseraceae by JosepH NELSON Rose. New species, chiefly from Cuba and exico, are described in the following genera: Ravenia (1), Zanthoxylum (3), Spathelia (1), Amyris (1), Elaphrium (7), and Icica (10). One new genus (Castelaria) of the Simaroubaceae is proposed, based on Castela Nicholsoni Hook., to which are referred 8 species, 2 from Cuba being new to science.—J. M. GREENMAN. bolae Antillanae.”—The eairin of a third fascicle completes the ym sixth volume of Professor UrBAN’s well-known work, Symbolae Antillanae. The fascicle recently issued cite the treatment of the Orchidaceae by ux. There are reco d 96 genera, to which are referred 505 raphy, make this a thoroughly scientific and standard work on the Orchidaceae of the Antillean region.—J. M. GREENMAN. Handbook of deciduous trees.—The tenth part (fifth section of second volume) of ScHNEIDER’s Handbuch has just appeared,™ the preceding part 9 North — = lora, Vol. XXV, part 3, pp. 173-261. New York Botanical Garden. May 6,1 to URBAN, [., sens Antillanae seu fundamenta florae erie Occidentalis. Vol. VI, fasc., 3., pp. 433-721. Leipzig: Fratres Borntraeger. 1910. ™ SCHNEIDER, C. K., Illustriertes Handbuch der Rees Zehnte Liefe- rung (fiinfte Lieferung des zweiten Bandes). Imp. 8vo. pp. 497-757. Jigs. 329-419- Jena: Gustav Fischer. 1911. M 5. tort] CURRENT LITERATURE 161 having appeared in 1909." It contains descriptions, with illustrations, of the angiospermous trees of central Europe, both native and under cultivation. The present part begins in the midst of Rhododendron and ends with Viburnum. —J:M.C, NOTES. FOR STUDENTS Current taxonomic literature.—E. BRAINERD (Bull. Torr. Bot. Club 38: 1-9. pl. r. 1911) presents an article entitled “Further notes on the stemless violets of the South,” and describes two new varieties.—R. E. BucHANAN (Mycologia 3:1-3. pls. 34, 35. 1911) describes and illustrates a new hyphomycete (Thy- rococcum humicola), obtained from pure cultures—C. Dr CANDOLLE (Phil. Journ. Sci. Bot. 5:405-463. 1910) presents “A revision of Philippine Pipera- ceae”’ in which he recognizes 22 species of Peperomia and 123 of Piper. O the total number about 50 are new to science—J. Carport (Rev. Bryol. 38:33-43. 1911) under the title “Diagnoses préliminaires de Mousses mexi- caines”’ tas published several new species of mosses, based mainly on col- lections made in southern Mexico by C. R. Barnes and W. J. G. LAnp in 1908.—C. CHRISTENSEN (Arkiv fér Bot. 10?:1-32. pl. z. 1910) presents an article “On some species of ferns collected by Dr. CARL SKOTTSBERG in tem- perate South America” in 1907-1909. The paper includes descriptions of 3 species new to science.—W. N. CLuTe (Fern Bull. 18:97, 98. 1910) describes and illustrates a new species of Polypodium (P. prolongilobum) and a new variety of P. vulgare L. from Arizona.—E. B. Copetanp (Leafl. Phil. Bot. 3:791-851. r910) enumerates upward of 250 species of ferns from Mount Apo, Philippine Islands; of this number 16 are described as new. The author states: “It is probable that this is the richest known fern flora in the world.” Polypodium and Dryopteris are the predominating genera.—A. D. E. ELMER (Leafl. Phil. Bot. 3:853-1107. 1910-1911) records further data concerning the flora of the Philippine Islands, and describes 138 species of flowering plants as new.—M. L. FERNALD (Rhodora 13:4-8. 1911)has published a new species of Scirpus (S. Longii) from Massachusetts and New Jersey.—D. GRIFFITHS (Rep. Mo. Bot. Gard. 21:165-175. pls. 19-28. r910) in continuation of his studies on the genus Opuntia has described and illustrated 10 new species indigenous to southwestern United States and northern Mexico.—E. HassLEeR (Rep. Nov. Sp. 9:1-18, 49-63, 115-121. 1910-1911) has published several new . species, varieties, and forms in the genus Mimosa and in the families Big- noniaceae and Solanaceae from Paraguay. One new genus (Rojasiophyton) of the Bignoniaceae is proposed.—F. D. Heap and F. A. WoLF (Mycologia 3: 5-22. 1911) have published 41 new species of Texan fungi—A. A. HELLER (Muhlen- bergia '7:1-11, 13-15. rg11) records further results of his studies on “The North American lupines” and describes two new species: L. sabulosus from the sand hills near San Francisco and L. apodotropis from Oregon.—A. F. G. Kerr and W. G. Cramp (Kew Bull. 1-60. rorr) under the general title of ” Bot. GAZETTE 48:312. 1900. 162 BOTANICAL GAZETTE [AUGUST “Contributions to the flora of Siam’ have issued an interesting paper on the little known flora of that region. A general sketch of the vegetation is from the pen of Dr. Kerr, and a “List of Siamese plants with descriptions of new species” is the work of Mr. Crars. Several new species are added to the flora and one new genus (Pittosporopsis) of the Icacinaceae is proposed.—W. Liesky (Acta Hort. Petrop. 26:119-616. pls. 3-6. 1910) continues his im- portant publications on the flora of central Asia. The present contribution contains descriptions of several new species, particularly in Astragalus and Po ntilla. The treatment of the latter genus was contributed by the noted specialist Ta. Wotr.—T. H. MacsripE (Mycologia 3:39, 40. pl. 36. 1911) describes and illustrates a new genus (Schenella) “pebiealy referred to the yxomycetes. The material on which the genus is based was found growing on a decaying pine log in the Yosemite Valley, California——M. E. McFapDEN (Univ. Calif. Pub. Botany 4:143-150. pl. 19. 1911) presents an account of “A Colacodasya from southern California,” and in conjunction with Dr. W. A. SET- escribes a new species (C. verrucaeformis) found growing on Mychodea episcopalis J. Ag.—E Ma MERRILL and M. L. Merrirr (Phil. Journ. Sci. Bot. 5:371-403. pls. 1-4. I map. 1910) in a concluding article on “The flora of Mount Pulog” have published Ir new species of Sympetalae. Two new genera are described by Mr. MERRILL, namely Loheria = the Myrsinaceae and Merrittia of the Compositae—W. A. Murritt (Mycologia 3:23-36, 79-91. 1911) has issued the first two papers of a proposed series of articles on ‘‘The Agaricaceae of tropical North America,” recording new species in Leucomyces, imacella, Russ 7:11, 12. 1911) describes a new species of Schmaltzia (S. pubescens) and one of Carduus (C. vernalis) from Colorado.—F. W. PENNELL (Torreya 11:15, 16. 1911) records a new species of Gerardia (G. racemulosa) from New Jersey.— C. B. Roprnson (Phil. Journ. Sci. Bot. 5:465-543. 910) begins a monographic onsideration of the “Philippine Urticaceae,” treating 9 genera to which are referred 86 indigenous species, about one-half being new to science. One new genus (Elatostematoides) is proposed.—E. Rosenstock (Rep. Nov. Sp. 9:67-76. ome has published 16 new species of ferns, 5 of which are from Costa Rica. . A. Ryppere (Bull. Torr. Bot. Club 38:11-23. 1911) in continuation of his “Studies on the Rocky Mountain flora” has described several new species of Compositae.—G. SCHELLENBERG (Mitt. Bot. Mus. Univ. Ziirich, No. 50, pp. 1-158. roro) under the title “Beitrage zur vergleichenden Anatomie und zur Systematik der jaa has published or results of a detailed study of this family, recognizin enera and over 100 species. One new genus (Santaloides), based on . Afzelii Planch. He Africa, is new to science. —A. K. ScHINDLER (Rep. Nov. Sp. 9:123-125. 1911) under the title “ Halorrha- gaceae novae I” includes two new species of Gunnera from Peru.—R. SCHLECH- TER (ibid. 21-32) has published 20 new species of orchids, 13 of which are from Central and South America.—F. J. SEAVER (Mycologia 3:57-66. 1911) pub- lishes the results of studies in Colorado fungi and includes descriptions of Ig1t] CURRENT LITERATURE 163 two new species, namely Ascobolus xylophilus and Godronia Betheli—D. R. SUMSTINE (ibid. 45-56. pls. 37-39) under the title of “Studies in North Ameri- can Hyphomycetes I” presents a taxonomic treatment of Rhinotrichum and Oliptrichum, recognizing for the former 13 species, of which 3 are new to science.—F. ISSEN (Broteria, Ser. Bot. 9:121-147. pls. 5-9. 1910) in an article entitled ‘‘Hypocreaceae Riograndensis” has published 15 new species. The same author (Beih. Bot. Centralbl. 2'77:384-411. 1910) under the title “Fungi Riograndensis’’ lists about 150 species from southern Brazil, 10 of which are new to science. One new genus (Creosphaeria) is characterized and is said to be intermediate between Rosellinia and Hypoxylon.—I. TiwEestRoM (Am. Mid. Nat. 1:165-171. pl. rz. 1910) has published 3 new species of Aquilegia from western United States and gives a synopsis of 10 recognized species.—I. URBAN (Ber. Deutsch. Bot. Gesell. 28:515-523. pl. 15. 1911) has published a new species of Loasa (L. Plumeri) and a new monotypic genus (Fuertesia) of the Loasaceae from Sto. Domingo.—W. WerINGART (Monats 261. 1910) under the title “Bolivian Mosses, Part II,” has described 18 new species. The same author (Bull. Torr. Bot. Club 38:33-36. torr) records two new species of mosses from Panama.—N. N. WoronIcHIN (Bull. Jard. Imp. Bot. St. Petersb. 11:8-19. 1911) records a list of fungi collected in south- eastern Russia, and includes a new ascomycetous genus Saige parasitic on the leaves of Caragana frutex Koch—J. M. GREENM The number of chromosomes.—In 1909 STRASBURGER made a cytological study of the parthenogenetic Wikstroemia indica, and now he has succeeded in securing from the rather inaccessible Himalaya region material of the nearly related W. canescens, in which fertilization regularly occurs. From an investigation of W. canescens and a study, of the literature of forms with unexpectedly large numbers of chromosomes, some interesting conclusions are reached.%3 High chromosome numbers can be shown to be the result of multiplica- tion of whole chromosomes, so that the organism becomes polyploid, with a diploid gametophyte and tetraploid sporophyte, instead of the usual haploid and diploid generations. Such increases in chromosome numbers must be referred to mitotic division: which does not get to the separation of the daughter chromosomes, or, if daughter nuclei are formed, they reunite. The increase in number comes usually from a longitudinal division, which gives like products, and it is probable that the phenomenon takes place in the fertilized but not yet divided egg. The increase in the number of chromosomes is accompanied by some increase in the size of the nucleus and protoplast. In the nuclei of sporophytes which are more than diploid, the homologous 3 STRASBURGER, EpuARD, Chromosomenzahl. Flora 100:1-50. pl. 6. 1910. 164 BOTANICAL GAZETTE [AUGUST chromosomes are grouped in pairs, and not in tetrads in tetraploid nuclei. In the triploid nuclei of the endosperm of angiosperms, there are both paired and unpaired chromosomes. In the mother cells of polyploid plants there are always only bivalent chromosomes (gemini), and never a complex of more than two chromosomes as elements of the reduction plate. In triploid-nuclei of the sporophyte of hybrids which result from a union of haploid and diploid gametes, there are both paired and single chromosomes, and in the mother cells of such plants both paired and single chromosomes appear. From a study of the various pairings it seems that they depend upon an attraction between homologous chromosomes, so that this homology, rather than any maternal or paternal origin, determines the formation of pairs, and it may be possible that a pair of two homologous chromosomes may be derived from the same sex product. The increase in the number of chromosomes has often led to parthenogenesis (eiapogamy), but there is also parthenogensis without any increase in the number of chromosomes. The large number of chromosomes does not always result from i ciettaal division, but may be due to a transverse division, and in this case there is no increase in the size of the nucleus and no loss of sex occurs. Zoological litera- ture shows many instances of analogous phenomena. This paper suggests a wide range of problems for cytological investigation, and obviously it has an important bearing upon the theory of the individuality of the chromosome.—Cuartes J. CHAMBERLAIN. Sixteen-nucleate embryo sacs.—The ovule of Euphorbia procera“ has sev- eral hypodermal archesporial cells, each of which divides into a tapetal cell and a megaspore mother cell. The two reduction divisions take place in the mother cells, but are not accompanied by wall formation, so that each mega- spore mother cell now contains four megaspore nuclei, or rather, four mega- spores not separated by walls. At this stage all the tetrads degenerate except one, and in this each megaspore nucleus undergoes two successive mitoses, g rise to a 16-nucleate sac. Several other species of Euphorbia were examined, and all had a single archesporial cell and a typical 8-nucleate sac. MopiLewskr’ had previously shown that in the 16-nucleate stage of £. procera the nuclei are arranged in four tetrad-like groups, from each of which one nucleus moved to the center of the sac to form the endosperm nucleus. The micropylar group formed the egg apparatus and the chalazal group the antipodals, while the two lateral groups resembled the egg apparatus. Double fertilization was observed, the second male nucleus fusing with the four nuclei at the center of the sac, so that the endosperm nucleus resulted from the fusion of five nuclei. The chromosome situation was not determined. % MopILEWSKI, J., Weitere eae zur op tag einiger Euphorbiaceae. Ber. Deutsch. Bot. Gesell. 28:4 I oO. § —__—, Zur re abtidane yon papers procera. Ber. Deutsch, Bot Gesell. 297: 21-26. pl. 1. 1908 1911] CURRENT LITERATURE 165 MopiLewskr® has also described a 16-nucleate embryo sac in Gunnera chilensis, in which case the four megaspores, not separated by walls, all take part in forming the embryo sac. Although no definite proof was obtained, he believed the embryos to be parthenogenetic An interesting embryo sac is described by DESSIATOFF, 7 who finds 16 nuclei in Euphorbia virgata at the fertilization period. The 16 nuclei come from one ° megaspore, and consequently the situation is somewhat different from that found in Peperomia, where 4 megaspores enter into the formation of the sac. The 16 nuclei are arranged in four groups of four each, and one nucleus from each group moves to the center of the sac, where the four fuse to form the endosperm nucleus. There are three antipodals, and an egg apparatus of two synergids, and an egg. The,two other groups remain at the side of the sac and resemble the egg apparatus. In general, this embryo sac resembles that of the Penaeaceae as described by Miss StEPHENS.—CHARLES J. CHAMBERLAIN. e sperm nuclei of Lilium.—Since zoological literature furnishes no instance of the fertilization of the egg by a naked male nucleus unaccom- panied by any cytoplasm, and since the male nucleus in plants has in nearly all cases been shown to be accompanied by cytoplasm, definite proof of fertiliza- tion by a naked nucleus is worth recording, especially since the nucleus is regarded by many as the sole bearer of hereditary qualities. Both Srras- BURGER and KoOERNICKE have claimed that in Lilium the sperm nucleus, at the time of fertilization, is not accompanied by any cytoplasm. A paper by NAWASCHIN,® the discoverer of double fertilization, gives a very complete account of the generative cell and development of the sperm nuclei in the classic Lilium Martagon. The excellent technic, remarkably close series of scription and conclusions. The cytoplasm of the generative cell has a finely granular structure up to the anaphase of the division of its nucleus, at which time its cytoplasm begins to mingle with the general cytoplasm of the pollen tube. The mitosis which gives rise to the two male nuclei is characterized at every stage by sharply differentiated chromosomes, so that the sperm nuclei do not reach the resting stage, but remain in the condition character- istic of telophase. Consequently, it is not improbable that the mature nuclei are capable of movement. The achromatic spindle is scanty and in some cases doubtful, and in others cannot be identified at all, so that it is probable that %6 MopILEwskI, J., Zur Embryobildung von Gunnera chilensis. Ber. Deutsch. Bot. Gesell. 26a: 550-556. pl. 11. 1908. 7 Desstatorr, N., Zur Entwickelung des Embryosackes von Euphorbia virgata. Ber. Deutsch. Bot. Gesell. 29:33-39. figs. I7- 1911. *8 NAWASCHIN, SERGIUS, Niheres iiber die Bildung der Spermakerne bei Lilium Martagon. Ann. Jard. Bot. Buitenzorg. II. Supplement IIT. 871-904. pls. 33, 34. IQIo, 166 BOTANICAL GAZETTE [AUGUST the chromosomes in this mitosis move independently of any spindle.—C. J. CHAMBERLAIN. Studies in ferns.—Apogamy in Cystopteris fragilis, hybridization in A sple- nium, and conditions of heredity in certain ferns, have been investigated by A. HEILBRONN.” The group last considered includes, as true varieties, the following: Aspidium Filix-mas var. grandiceps, A. aculeatum var. cruciato- polydactylum, Athyrium Filix-femina var. corymbiferum, A. Filix-femina var. multifidum, A. Filix-femina f. multifidum Mapple-Beckii, A. Filix-femina var. laciniatum and var. purpureum Lowe. Others not considered true varieties are Athyrium Filix-femina var. Fieldiae Moore, A. Filix-femina {. multifidum minus, and -Aspidium angulare {. grandidens. The general conclusions of the author are: (1) Cystopteris fragilis {. polyapogama develops prothallia which show the power of developing sporophytes from unfertilized egg cells or by vegetative apogamy, the two cases sometimes being side by side; (2) the question as to whether Asplenium germanicum is a hybrid between two forms is not yet settled, but by crossing Asplenium septentrionale (female) and A. Ruta-muraria (male), a plant was obtained which stands nearer to A. ger- manicum than any other known form; (3) some fern-forms which had not been investigated before appear apogamous. Of the different forms of Athy- _ rium Filix-femina from England, some are true varieties and some revert. Attempts to obtain forkings artificially were unsuccessful—Norma E. PFEIFFER Water-cultures of fern prothallia.—In a short paper H. FiscHER” gives some of his results with the germination of fern spores, in obtaining material for his work on variation, hybridization, etc. He states the advantages of water-cultures over solid substrata as being threefold: the chemical constitu- tion can be regulated; the cultures are cleaner, and material is fit for micro- tome sections without extra care; the spores may be sowed as thick as desir- able, and easily diluted, like a solution, if too close together on germination. The danger lies in the drying out of cultures, or too great evaporation, resulting in plasmolysis. A second danger lies in the production of abnormal forms by Arthur Meyer’s ict, the formula of which he gives. He finds that changing one compound or its concentration, changing the reaction of a solution, etc., often produce the desired germination. But evidently there is no general rule for this, as there is none for the length of time after ripening that a spore will germinate. In Asplenium Serra, herbarium material germinated after 48 years. In some few cases the author is as yet unable to induce germina- tion.—NorMaA E, PFEIFFER. 9 HEILBRONN, ALFRED, Apogamie, Bastardierung, und Erblichkeitsverhiltnisse bei einigen Farnen. Flora (n.s.) 1: 1-42. figs. 43. 1910. 20 FiscHER, Huco, Wasserkulturen von Farnprothallien, mit Bemerkungen tiber die Bedingungen der Sporenkeimung. Beih. Bot. Centralbl. 27':54-59. 1911 tort] CURRENT LITERATURE 167 Development of banana pollen.—An extensive investigation of three races of the edible banana (Musa sapientum) has shown that they can be f be designated as vars. univalens, bivalens, and trivalens. The volume of the nuclei, but not their surfaces, is in the ratio 1:2:3. With the increase in the number of chromosomes came disturbances in the development of pollen, some of the chromosomes not passing to the poles, but remaining behind and forming extra nuclei. The size of the tetrad varies in a given anther, although the number of chromosomes in the entire tetrad is constant. Sometimes as many as eight pollen grains are formed from a single mother cell. Prochromosomes are easily distinguished in the pollen mother cell, and in Musa Dole TiscHLER was able to show that the number of prochromosomes was equal to the diploid number of chromosomes. Probably there is a fusion of prochromosomes at synapsis. The splitting of chromosomes at the strep- sonema stage TISCHLER regards as genuine and not merely apparent.—CHARLES CHAMBERLAIN arthenogenesis in Taraxacum.—Parthenogenesis in Taraxacum has been investigated again, this time by ScHKORBATOW” who writes in Russian, but adds a summary in German, from which the following points are taken: The removal of anthers does not in any way affect the germination of seeds. Various colors of seeds, like clear green and dark brown, may become fixed and hereditary. At metaphase of the first division in the embryo sac, the chromosomes show various and characteristic forms, but the chromosomes seldom take the arrangement belonging to the heterotypic mitosis, and when they do, the author regards the phenomena as atavistic. itotic divisions occur in the embryo sac, in the endosperm, and in early stages of the embryo, in the last case all the nuclei but one becoming resorbed, so that the cells are left uninucleate—CuHartEs J. CHAMBERLAIN. The origin of the vacuole.—Probably most botanists believe that the large vacuoles of plants arise by the coalescence of numerous smaller ones. A paper by BEnstry, dealing with the canalicular apparatus of animals, gives also a description of root tips and the tapetum of anthers. The fixing agent used was: neutral formalin (freshly distilled), 10 cc.; water, 90 cc.; potassium bichromate, 2.5 g.; mercuric chloride, 5.0 g. With this fixing ** TISCHLER, G., Untersuchungen iiber die Entwickelung des Bananen-Pollens. I. Archiv. fiir Zellforschung 5:622-670. pls. 30, 31. 1910. * SCHKORBATOW, L., Parthenogenetische und apogame Entwickelung bei den Bliithenpflanzen. Entwickelungsgeschichtliche ciao an Taraxacum officinale Wigg. Bot. Institut Charkow. pp. 43. pl. 1. figs. 4. 19 *3 BENSLEY, R. R., On the nature of the canalicular ears of animal cells. Biol. Bull. 19:174-194. figs. I-3. 1910. 168 BOTANICAL GAZETTE [AUGUST agent and Haidenhain’s iron alum haematoxylin, or Flemming’s triple stain, the young cells, especially of the dermatogen and plerome, show an intricate network of canals, and older cells show a gradual transition from the network, which is a single structure, to the familiar appearance obtained by current methods. This method promises to solve the problem of the origin of the vacuole, and at the same time it is excellent for nuclear structures.—CHARLES CHAMBERLAIN. Mitochondria.—The small bodies variously known as mitochondria, chondriosomes, chondriokonten, and chromidial substance, have been known to zoologists for some time, but it is only recently that they have attracted any serious attention among botanists. A short paper by Lewrrsxr* describes * the mitochondria in young cells of Pisum sativum and Asparagus officinale. In the root tip the mitochondria become transformed into leucoplasts, and in the stem tip into chloroplasts. The mitochondria divide and are believed to be an essential part of the cytoplasm. No mitochondria were found inside the nucleus, and the author does not believe that there is any passage of mitochondria between nucleus and cytoplasm. Division of mitochondria is figured and described.—CuarLes J. CHAMBERLAIN. Origin of the plastid.—For nearly twenty years the theory that the plastid is a permanent organ of the cell, arising only by the division of a preexisting plastid, has been generally accepted, doubtless on account of the thorough investigations of ScHIMPER and of MEYER. When Lewirskt’s paper appeared, laimi plastid arises only by the division of a pre-existing plastid. Their evidence seems more voluminous than convincing. It is to be hoped that this incipient controversy will settle the status of the plastid —CHartres J. CHAMBERLAIN. 24 LEWITSKI, G., Ueber die oa in pflanzlichen Zellen. Ber. Deutsch. Bot. Gesell. 28:538-546. pl. 17 oO. 25 MEYER, ARTHUR, eee zu G. Lewitskt: Ueber oa Chondriosomen in pflanzlicher Zallen, Ber. Deutsch. Bot. Gesell. 29:158-160. 1 Indigestion The use of Horsford’s Acid Phosphate is especially recommended in many forms of Dyspepsia and Indigestion, eden! where the patient suffers from ns in the stomach or chest, continued sense a hunger, nausea or acid stomach >For Nervous Disorders. The use of Horsford’s Acid Phosphate has been found sev onan ee valuable in nervous disorders, restoring energy, increasing mental an physical ondurenes and as a general tonic. HORSFORD’S ACID PHOSPHATE (Non-Alcoholic) I r druggist can’t supply cents to Me toy Chemical Wor - pesielilouiel: R. I. for trial size bottle, postage paid. The Typewriter That’s Ten Years Ahead Is the Typewriter for You. THE L, C. SMITH & BROS, TYPEWRITER Ball Bearings thro oughout and all the writing always in sight, measures a at every point to the highest scale of modern needs. Better work and more of it, ror efficiency th caer wid through, the L. C. Smith & Bros. Typewriter is the writing machine rang you. Send for the Book today. L. C. SMITH & BROS. pS ipicgginnry co. Syracuse, N.Y., MENNEN’ Borated Talcum FOR MINE For Prickly Heat and Sunburn Relieves all Skin Irritations Sample Rox for 4c stamp GERHARD MENNEN CO. ry ark, N. J, Trade-Mark Intending purchasers of a strictly first- class Piano should not fail to exam- ine the § merits specia: favorite vl renne seiened camel public on Rese of its unsur- vaaunk tone- even unequaled durability, ele- gance of design and finish. Catalogue mailed on applicatio THE SOHMER-CECILIAN INSIDE PLAYER SURP bigs © so OTHERS Favorable Term to onsible Parties HMER & COMPANY ars sth Ave., Cor. 3 YORE Educational Entertainment in all Sunday School or Bible Classes—lectures—talks or the like—and many enjoyable games and amusements are at the command of those who possess a Bausch lomb alopticon QFor church or home, this optically perfect ‘instrument provides a wide variety of in- structive and highly interesting diversion.. It is very easy to operate, gives good definition and can be used for lantern slides and arranged for opaque pictures—photographs, prints, drawings, etc. Q Send for circular 7D. Our name, backed by over balf a century o om experience, is on all our p Peteuay din GN i" microscopes, field glasses, projection apparatus, \ N7, j engineering and other scientific instruments. RY Bausch §9 lomb Optical G. @rw york * CHICAG®S AN FRANCISCE WASHINCTON s. LONDON ROCHESTER. NY. FRANKFORT SEGTIONALISM IN VIRGINIA By GHARLES HENRY AMBLER ROM the earliest colonial times Virginia was a land of sectional differences, which influenced to an important degree the course of her history. These differences and their results are treated in an able book by Charles Henry Ambler entitled Sectionalism in Virginia. Extensive research in the archives at Charles- ton, Richmond, and Washington, and the examination of numerous documents have given the author material which throws much new light on Virginia’s internal troubles in ante-bellum days. Mr. Ambler has divided his material into three periods, the first beginning with colonial times and ending with Bacon’s rebellion; the second including the emigration into the Piedmont, the Revolution, and the Constitutional Convention of 1829-30; and the the third begin- ning with the demand of the Trans- Alleghany section for a greater voice in the state government, which led to dismemberment just before the Civil War. Twelve maps illustrating the vote on important resolutionsare scattered through the book. 376 pp. THE UNIVERSITY OF GHIGAGO PRESS ILLINOIS . i2mo cloth postpaid $1.64 FINE INKS 4%? ryt For those who KN Drawing Inks Eternal Writing Ink Engrossing Ink * es 9 Photo M t te FHI UMS” 5 Peete meceter Pose aste Vegetable Glue, Etc. Are the Finest and Best Inks 582 Adhesives Em: self from the use and itsmellng in aay ind adhesives pony ote the Hig- and Adhesive a will be a they are a , clean, well At Dealers Generally. CHAS. M. HIGGINS & CO., Mfrs. Branches: Chicago, London 271 Ninth Street. Brooklyn, N. Y. 8 Why inch along like an old inchworm with that anti- quated hand aces of the typewriter carriage when you can go right tot touch on a Column Selector key of the a 10 Remington The Remington Column Selector is the great- est of all recent typewriter improvements. les the oper It enab e rator — tly Pye place the — where she wills, ski ppin as many columns e@ wi prim to the work to be don And this is only one ofa — = —— improveme the model 1 VISIBLE Remington Remington Typewriter Company (Incorporated) New York and Everywhere “HERE ARE THE FIVE COLUMN SELECTOR KEYS" ee ee ee THE ELEMENTARY SCHOOL TEACHER Edited by the Faculty of the Elem School o foe aan sity of Chicago. Published pret rp aadbah a July and ae wy ma ig a. ge Dae rs 50.0 yea ingle o cents; foreign postage, ks THE UNIVERSITY OF CHICAGO PRESS — WLINOIS _ ARR Ra RN ESCM SSE EU eJUDSON Freicit romwanoins co ates on household goods to all Western Wave Ape 0, 443 Marquette Bldg. os t. Louis, rs0r Wright Bldg. Los Angeles, 516 Central Bldg. oston, 736 Old South Bldg. San Francisco, 217 Front St, ork, 342 Whitehall ng _ ce) ? be cenit Mi g : IE a fed te veut as cis ir rs uld ¢ t : & SUPA o. eir There is genuine pleasure in CB ine use as we va wr nyse ni wi = s acy of with the aes ip xt a. P43 Gen be used repeated! snd “try ark ““O. K.” ped on every fastener. ot, Sead 10c for ‘aide box of 50, assorted. tfree. Liberal discount to the trade. The O. K. Mfg. Co., Syracuse. N. Y., U.S.A. Wois $250 AND UP ° THE ORIGINAL NON-LEAKABLE FOUNTAIN PEN stroke without shaking. A! That is a vital point — is lacking in J a Aes g we pens. u can readily unde rstand how this is de ee in a en we explain that pat b in use lies aiaaeraad in ink which ‘tome it moist and prepared for instant writing, positively eliminating the necessity of shaking. ways ready to write at the first Bog 0 that is not all of its strong features. The Moor carried in any position without the least me a Ealing. Has a large ink i agg Always freely and evenly, and is easily filled. Every Moore Non.Leakabl Fountain Pen carries with it the most unconditional guarantee. BE SURE IT’S A MOORE. ty Dealers Everywhere. } CANADIAN AGENTS, WJ. GAGE “£0, TORONTO, CAN. Nes Modern Constitutions By WALTER FAIRLEIGH DODD, Ph. Two vols., 750 pages, vo, cloth; net, ran postpaid, $5.42 HIS volume contains the texts, in English translation where English is tine nation, Australia, Austria-Hungary, Belgium, Brazil, Canada, Chile, Denmark, France, Ger oi Italy, —— Mexico, Netherlands, tins wa Portugal, Russia, a Sweden, ol cea oa the United Stat These constitutions have not pia tofore aes gealiable in aa one Englis collection, and a number o em have not before binders in English ‘eevee Each recede by a select list of the most important books dealing with the government of the country under consideration. The University of Chicago Press CHICAGO ILLINOIS Industrial Insurance in the United States By CHARLES RICHMOND HENDERSON HIS book, revised and enlarged for the English T speaking public, has already been published nal a es. rman se a summary of the European laws on workingmen’s in- surance against accident, sickness, invalidism, and old large S,. CO tions, and rail apter is direct legislation and another to employ er’s liability laws, Illustrations rie the movement are muni ion plans for policeman, fremen, and teachers; “also he cerond The appendix supplies bibliography, forms used by firms and corporations, text of bills, and laws on the 448 pages. 8vocloth. Price, $2.conet; postpaid, $2.19 Published by ——————— The University of Chicago Pre Press PRAGMATISM AND ITS CRITICS This is the clearest and most satisfactory summing up of the controversy that has yet appeared. Even the most technical matters are presented in such a way as to be intel- ligible to anyone who is genuinely interested in the movement, The book covers all the important points at issue, but special emphasis is laid on: (1) The historical development of the pragmatic movement; (2) Its relation to the conception of evolution; (3) The social character of pragmatic doctrines. The treatment is sympathetic and incisive. THE UNIVERSITY OF CHICAGO PRESS CHICAGO, ILLINOIS A Short History of Wales By OWEN EDWARDS Lecturer on Modern History at Lincoln College, Author . ‘“‘The Story of Wales,’’ etc. his book, by one of the most distinguis ished of iva Welsh scholars, will supply a long - the general reader now Latin or Welsh for its comprehension - is with mesma omg and goes down present day. hile py chapter is complet in nasi the Sesarai plan dyer etrical an y to see. The book is tally ¢ uipped ith 3 maries, s, pedigrees, and maps. 162 pages, 12m0, cloth, net 75 cents, postpaid 83 cents ApprEss DEPT. The abeicaity of sates Press Chicago, Illinois OME of the readers of this Periodical may be under the impression that Oriental rugs are luxuries whose attainment borders on guilty ex- travagance @ We are in a position to prove the contrary. For $20.00 or $25.00 we will send you a Persian rug on thirty days’ trial, at the expiration of which period we will refund the money if the rug is returned. @ The size of the rugs are from 6 to 7 feet long and from 3 to4feetwide. Thecolors desirable. Ifyou have an old rug to replace with a good Oriental, or a bare corner in your home to beautify, or if you wish to make a lasting, suitable gift, we would sug- gest that you send for one of these rugs. q Kindly state if $20.00 or $25.00 rug is desired, and give the size and color you prefer, and we select a piece as near to your requirements as possible. Q Visitors to New York welcomed. Correspondence upon matters pertaining to Oriental rugs invited. H. MICHAELYAN | Sete 7 ORIGINAL— GENUINE Delicious, Invigorating HOREICK’S “eee Better than Tea or Coffee Rich milk and malted-grain extract, in powder. A quick lunch. Keep it on your sideboard at home. IB” Avoid Imitations— Ask for “HORLICK’S”’ = peryenere @_ Have them bound in Preserve You Cloth or Leather. It will improve the ap- pearance of your library at a small Magazines fo. he University of Chicago Press has a well-equipped job bindery ge be pleased to quote prices. THE UNIVERSITY OF CHICAGO PRESS Mfg. Dept. Bindery CHICAGO The University of Chicago Press Announces that a representative stock selected from its list of books and pamphlets is carried by The Baker and Taylor Company 33 East 17th St., New York, N.Y. Patrons located east of Buffalo and Pittsburgh will effect a material saving in time by placing their orders through this agency. The Journal of the Association of Collegiate Alumnae Board of Editors AnnE Harp, Chairman, 2400 Hartzell St., Evanston, Ill. SOPHONISBA P. BRECKINRIDGE, 87 Lake St., Chicago, Ill. Mary Ross Potter, Willard Hall, Evanston, IIl. Louise Rots, 1935 Warren Ave., Chicago, Ill. ARAH WHITTLESEY WALDEN, New Haven, Conn. The Journal of the A i f Collegiate Alumnae is published four times a year, in the months of January, March, April, and May, by the Association of Collegiate Alumnae at the University of Chicago Press, 5758-60 Ellis Ave., Chicago, Ill. The subscription price is $1.00 per year; the price of single copies is 25 cents. Ad- dress orders to The University of Chicago Press icago, Illinois The Higher Education as a Training for Business By HARRY PRATT JUDSON, President of the University of Chicago “It must not be forgotten that no col- lege can insure an education to a young man. More definitely, no college gives an educa- tion. All that colleges can do is to provide to earn a living. It should also teach one how to live.”—From the Preface. —_—<—<—$<$<$<————————_. 56 pages r2mo, cloth postpaid 55 cents The University of Chicago Press Chicago - - - Mlinois —— Fifty-six © S) Volumes Issued THE MUSICIANS LIBRARY The masterpieces of Song and Piano Music, in a Series of Splendid Volumes, Edited with Authority, and Engraved, mings d,and Boun with Surpassing Excelle want Esterbrook’s PRICES Each Volume in heavy — cloth back rs i i ran cloth gilt Easiest Prices include transportation. Nockicts giving writing full particulars, special features, and complete list of Volumes published, ae on request. Longest Write for Special Prices to Pub- wearing lic, School, and College Libraries pa half a century, The Paes Tayo Steel Pen Mfg. Co., 5 John —. a Works: Camden, N. J. OLIVER DITSON CO., Boston CHAS. H. DITSON & CO., New — A CHOCOLATE or RARE QUALITY The Unfolding of Personality as the Chief Aim of Education By THISELTON MARK, M.A. Lecturer on Education in bo i University of Manchest ia NTEREST in the study of child develop- ES ment from fv f - ATE tional psy aig 5 sivabonttien ta METROPOLITAN, Sie CHOCOL the teacher as as udent of ii education. To study in the light of modern psychology “‘the charactistlisie endowments of human nature,” and to present “a view of education which has the unfolding of per- sonality as its oe aim” is is the purpose o this book. T eriences of the with children of all ages make this book a OLATE , ‘ : . eyo Al (nN ture of child study. Suggestions and illus- Aga trations are added at the end of each chapter, giving directions and methods for study. a8 QUALITY. CONNOLSSEDRS _ © | NESS an ano FLAVOR 224 pages r2mo, cloth $1.07 postpaid THE Unvesiry OF CHICAGO PRESS TEN CENTS & FI (VE E CENTS HICAGO, ILLINOIS SOLO EVERYWHERE The University of Chicago Press FOREIGN AGENCIES FOR BOOKS AND PERIODICALS British Empire THE CAMBRIDGE UNIVERSITY PRESS Fetter Lane, London, E.C., England Continental Europe TH. STAUFFER Universitatsstrasse 26, Leipzig, Germany Japan and Korea MARUZEN-KABUSHIKI-KAISHA 11-16 Nihonbashi Tori Sanchome, Tokyo, Japan INQUIRIES AND ORDERS WILL RECEIVE PROMPT ATTENTION TWO MODERN MATHEMATICAL TEXTBOOKS First-Year Mathematics for Secondary Schools E WILLIAM y GEOR Professor of the enetndk of Mat adie: and aaassas in the ai na Education of a University of Chicago ted by the Instructors in Mathematics in the University High School pages, 12mo, elath; _— id $1.13 The object of this new course in mathematics is to do away with the present artificial divisions of the subject and to give it vital connection with the —— cre experience. The to following up the notions of mensuration into their geometrical iio and (3) to recon noitering a broadly interesting and useful field of algebra. This means postponing the scientific and purely logical ee of algebra to a later peri riod. A Man r Teachers to Accompany “First-Year Mathematics” is now ready. Price, 89 cents rere bi Second-Year Mathematics for Secondary Schools By GEORGE WILLIAM MYERS tructors in Mathematics in the University High School 290 conde on cloth; postpaid $1.63 oc Mathematics lays chief emphasis on geometry, as First-Year Mathematics does on algebr The re ‘texts cover the essentials of what is commonly required of all pupils in the first two years of secondary schools in this country, and include, in addition, the elementary notions of plane trigonometry through the solution of right triangles, as well as an introduction to some topics of formal algebra not usually treated in secondary te ee THE UNIVERSITY OF CHICAGO PRESS Chicago, Illinois There are quantities of dust floating in the air of the -ordi- nary schoolroom, brought in from the streets and raised from the floor by the constant movement of the children’s feet. Science’? has ~ proved that dust. is a favorite nesting place for disease germs. . It follows that at every breath the children are in danger of being infected by the germs contained in the floating dust they inhale. The best known prevent- ive of disease-carrying dust is Standard Floor Dressing. s easily swept away without again ris- ing into the air. The air is thus kept untainted; the spread i utset. of disease is checked at the o Our free illustrated booklet om dust dangers and how to avoid them con- paid on request. Write for it today. Not intended for household use. Standard Oil Company : ——— GET THE GENUINE Baker’s Chocolate 32, SB SN ts Bae st — 2 at Pos Be Wra ¥ " Deade Be Marko on the Back FINEST IN T THE WORLD or Cooking and Drinking d. || | TH E PALM 3 f f 7 TH th axe THE BoTANICAL GAZETTE September ro1rr Editor: JOHN M. COULTER CONTENTS A Preliminary Report on the Yearly Origin and Dis- semination of Puccinia graminis + Frederick J. Pritchard Evaporation and Plant Succession George Damon Fuller The Tetranucleate Embryo Sac of Clintonia . Wilson Smith The Embryo Sac of Physostegia Lester W. Sharp The Brazil Nut W. J. Young Briefer Articles An Imbedding Medium for Brittle or Woody Tissues H. M. Benedict te Current Literature iz * The University of Chicago Press x CHICAGO, ILLINOIS THE CAMBRIDGE eae tee London jae Edinburgh bree WESLEY & SON, London H. STAUFFER, Leipzig THE ico: aacoenieak Tekyo, Osaka, Kyoto The Botanical Gazette — a Monthly Journal Embracing all Departments of Botanical Science : Edited PY Jous M. COULTER, with the ASsistatice of ee members of the botanical staff of me University of Chic Issued September re 1951 Vol. LIE = © CONTENTS FOR SEPTEMBER 1931 gS oe as A PRELIMINARY REPORT ON THE -YEARLY ORIGIN AND DISSEMINATION. OF -PUCCINIA GRAMINIS (with PLATE IV). Frederick J. Pritchard - 169 EVAPORATION AND PLANT SUCCESSION. CONTRIBUTIONS FROM THE-HULL BOTANICAL 3 LABORATORY 147 (WITH SIX FIGURES), . George Damon Fuller +e 932 oo THE TETRANUCLEATE EMBRYO SAC OF CLINTONIA (WITH PLATE v). R. Wilson er Ss oy ORE ee Ta ee eG ei So eS eae THE EMBRYO SAC OF PHYSOSTEGIA (with pLates vi-vu). Lester W. Sharp - -- 218 THE BRAZIL: NUT (with PLATE ‘VINE AND ONE FIGURE). W.J. Young 9 - - «= 226 us ceyeae ARTIC N IMBEDDING ReeSe FOR BRITTLE OR Wooby Tissues. 4. AL Benedict - : - 232 CURRENT. Diba gon hs Se ee eo ie seh See SL ve ae ee (PLANT AND ANIMAL BREEDING FOR \SECONDARY SCHOOLS. | POPULAR MANUALS, MENDELISM oa i DEORE HONORS 3) SE RR ee CR TAS en ae aa . NOTES FOR STUDENTS oY bee ee nee eer ee ee oS oe eg ee ee ee e Botanical Gazette is published BESS ‘|The sliseription price is $7. 90 a year; the price of ape copies is 75 cents... {Postage is tote’ by. the oe sri = orders from the United States, Mexico, Cuba, Porto Rico, Panama Cai nal e, Republic of Pate a, Hawatian Ielands, Phiipnae ; | oman | oe Postal Un agen: cents on fo ay re tt (total $784), 0 * ee co 2% 11 cénts (total engine. hy : : “The following ea have been oe ted and are authorized to oe the “a hale indicated : ia For the British Empire: The Cambridge University Press, Fetter Lane, E.C,, and Wiliam. a Sx Wade & Son, ser asse r Sheet inal? gine Yearly subscriptions, including stages Sr 125. ach; single Stites incfading! soars oF 6d€ oe _ ~~.” For the Continent ‘of Eur he S quis ‘Universititestrasse 26, Leipzig, eee Yearly § sub-- *. scriptions, including postage, M we nae single copies, inclu me fy ostage, M, 3. pe oF or Japan and Korea: The Maroze en- Kabus hiki-K aisha, 6 Nihonbashi Tori Sadonie, Fokyo,. _. , Japan. way pay Lge includ postage, Yen 1S. 75 pci are? PES including postage, Ven oe ~Lysea e cee eS -. Claims miss umbers ahbaia® be made eithin the month followi ing the regular month of publi-. ca — cation. ra ophdets expect to supply missing numbers free only when.t ey have been los tin transit. > _ Business correspondence should be addressed to The University of Chicas gee Chicago, De es : *f "Communications for the editor should be Gerke sed to him at the University» of Chicago, Chicago, Hy 4 mtributors are requested to write scientific aud proper names with partic ar care, to use'the metric ‘ system of of = and: bie we and in. ations to follow. the form shown i in the pages ¢ of the ot ayes ; ge k apers it n éxce ~ ‘of aries th sepia sihetes are not accepted wales the author is willing to pay the eee "+ cost of the addition nal pages,in n-which case the number of pages in the volume is correspondingly gee ased. A Hilustra are furnis Ags without cast to Suthar aly feat adi or Some = upplied, copy? 5 © Of the: saxgestions ‘made in ¢- January’ number, he 07, will be sent = Sepuce “It is adv an to. - eonfer with the cas ors as . gab stincs requ ry article to be Ss ie if desired, must be ordered in a ‘publication. “Fenty ie separate of original Jes without cavers v8 ik be supplied ion * ‘: @ showing approximate of additiona been is printed on pee r blank which accompa ee will be nt = ae ery = : ‘ 4 ; 2 a VOLUME LItI NUMBER 3 ey SS BOTANICAL (GAZETIE SEPTEMBER 1917 A PRELIMINARY REPORT ON THE YEARLY ORIGIN AND DISSEMINATION OF PUCCINIA GRAMINIS FREDERICK J. PRITCHARD (WITH PLATE IV) Introduction The annual reappearance of Puccinia graminis Pers., the black rust of cereals, and its dissemination among the various species of the Gramineae, have long remained obstinate problems. For nearly a century botanists and also agronomists, because of its economic importance, have endeavored to discover how this fungus passes the winter and spreads to the grain fields. A review of the literature, to bring out certain points which have been too much overlooked by those who are committed to the conception that the barberry is the sole source of spring infection, will be of interest in connection with the data which my own observations afford. The barberry was considered a disseminator of rust by careful observers centuries ago. Even as early as 1660, as a result of their reports, an act of Parliament was passed at Rouen (22) con- demning the use of this shrub in the vicinity of grain fields. A similar law was passed in Mass. (28) in 1755. Successive measures of this nature were subsequently enacted throughout Europe (3). Proof of the influence of the barberry on rust contagion was furnished by ScHGLER (29), who in 1818 succeeded in infecting * Cited by ErrKsson. 169 170 BOTANICAL GAZETTE [SEPTEMBER rye with aecidiospores from barberry leaves. SCHOLER’s publica- tion, however, remained buried until brought to light by NIELson. Infection of the barberry with P. graminis was not accomplished until 1865, when DE Bary (3) readily infected the young leaves with germinating sporidia, thus establishing the heteroecism of the organism. Unfortunately he was unable at the same time to germinate the mature aecidiospores, either fresh or after various periods of preservation, and hence the cereal host species was not reinfected, although the following year he accomplished this upon young rye plants. The distance rust is spread from the barberry is variously estimated by different writers. MARSHALL (24),? who set large barberry bushes in the grain fields and made careful observations, states that the rust extended 10 yards in the direction of the pre- vailing wind. SCHOLER (29), on the other hand, used small bushes and found that it scattered over an area of 30 to 40 square feet. Much greater distances are frequently recorded in the literature, although usually based upon casual observation or opinion. WITH- ERING (33),° for instance, advises that no barberry bushes should be planted within 300-400 yards of a grain field. The absence of the barberry and Mahonia in several regions where Puccinia graminis is prevalent, as cited for Ecuador by LAGERHEIM (21), seems to indicate that the heteroecism of the fungus is merely facultative. According to Barctay (1), P.- graminis is also commonly present in Jeypore, India, while the nearest barberry bushes are nearly 300 English miles distant. Moreover, ‘‘the aecidia are formed in summer, while the wheat and barley are grown in winter and harvested in April or May.” In this same category ZUKAL (34) places Bosnia and Herzegovina, where, according to Branpis (34), the aecidial hosts, if present at all, are very rare. Perhaps the most striking case of this kind is in Australia, where P. graminis causes enormous damage to wheat, yet the barberry is not present and the aecidial stage has never been found. The existence of a perennial mycelium, although established for a 2 Cited by Artuur, Bull. Torr. Bot. Club 31:113. 1904. 3 Cited by Ertxsson and HENNING (16). tort} PRITCHARD—DISSEMINATION OF PUCCINIA r7t number of rusts, has never been proved for P. graminis. Erixs- SON (13, 14, 16) found the mycelium scarcely extending beyond the contour of the pustules. Dr Bary held that the development of the rust begins anew each year by the “germination of the teleu- tospores alone.” : P. graminis was formerly considered one species capable of infecting various members of the Gramineae, and this supposedly wide range of infecting power was thought to conduce to its spread. Errksson (16), however, after extensive inoculation experiments in Sweden, divides it into the following biological forms, which he finally classes as species: Puccinia graminis secalis (Secale cereale, Hordeum vulgare, and Triticum repens). ; Puccinia graminis avenae (Avena sativa). Puccinia graminis tritici (Triticum vulgare). Puccinia graminis airae (Aira caespitosa). Puccinia graminis poae (Poa compressa). Puccinia phlei-pratensis (Phleum pratense). CARLETON’S (10) experiments in America, however, do not support Eriksson and HENNING’s results. He finds no dis- tinction between the forms on wheat and barley. His results appear to establish two things: (1) “that the forms of black stem rust on wheat and barley, Hordeum jubatum, Agropyron tenerum, A. Richardsoni, and Elymus canadensis glaucifolius, are identical, with the probability that those on Elymus virginicus muticus and Holcus lanatus should be included; (2) that the black stem rust of Agropyron occidentale is physiologically distinct from any other.”’ Direct inoculation of the gramineous host with the germinating teleutospores has received some attention, although not as much as it deserves. Foremost among these experiments are probably those of DE Bary, who showed that the germinating sporidia of P. graminis would not infect the leaves of Triticum vulgare, T. repens, and Avena fatua. THUMEN (31), however, asserts that the sporidia of Melamspora salicina infect the willow quite as easily as do the uredospores. PLowricut (27) also, in a detailed report, claims to have infected wheat plants directly with sporidia (teleuto- bearing straw), although he afterward informed KLEBAHN that 172 BOTANICAL GAZETTE [SEPTEMBER “his work rested upon an error.’’ Other failures to infect wheat with germinating sporidia are reported by WARD (32) and Errks- SON (15), though no mention is made of the number of trials nor the point of inoculation. Notwithstanding these failures, BRE- FELD (8) thinks further attempts should be made to infect young cereals with germinating teleutospores. His discovery that only the youngest tissues of cereals are penetrated by smut sporelings gives encouragement for numerous experiments in this direction. The hardened tissues may offer too much resistance to the delicate germ tubes of the sporidia, he says, which bore directly through the epidermis instead of entering through the stomata, as do the germinating uredospores and aecidiospores. The behavior of the germinating teleutospores is influenced somewhat by their environment. MacGnus (23) found that teleu- tospores of P. graminis kept under a thin layer of water formed a germ tube instead of a promycelium. These results were after- ward confirmed by BLACKMAN (5), who also included two other genera. Other factors are sometimes operative, as KIENITZ- GeRLorr (18) reports that thin-walled teleutospores of Gymno- sporangium clavariaeforme also form a germ tube. When teleu- tospores germinate in air, however, they almost invariably form sporidia. This is true of P. graminis even in Australia, where it has no aecidial host species. The uredospores of P. graminis soon lose their viability, accord- ing to De Bary (3), in one to two months if kept dry. BOLLEY (6, '7), however, obtained a germination of 5 per cent after exposing them to air and sunlight during the month of August, and even claims they may live over winter. Christman (11) failed to ger- minate them after November 23, although the uredospores of P. coronata were viable the 26th of January, and those of P. rubigo- vera the 21st of March. Perhaps the most extensive experiments of this kind have been made by Eriksson and HENNING (16), whose results show that the uredospores of both P. graminis and P. glumarum are unable to survive the winter in Sweden. The absence of fresh uredo pustules during two or three months in the spring is cited as additional proof, since the period of incubation after inoculation with uredospores is only about ten days. The rott| PRITCHARD—DISSEMINATION OF PUCCINIA £73 statement is also made by KLEBAHN (19) that “in Germany P. graminis does not appear to pass the winter as uredo.”’ CARLETON (9) found this to be true in Kansas, and in a two weeks’ trip through Texas in December 1895, he could find no rust on winter wheat or oats, although it was present there in abundance the previous summer. The mycelium of the rust is not limited to the leaves and culms of cereals, but also enters the seed. ERIKsson (14, 16) found it in abundance in the “peripheral tissues’’ of grains, but was unable to trace it into the young seedlings. ZuKAL (34) has made similar discoveries, and even found it in the seed coats of barley which was furnished by Eriksson and supposed to-contain mycoplasm. Spores of the Uredineae are frequently present in the seed of the host. SmrrxH (30) found teleutospores of P. graminis in oat grains lying next to the gluten layer, and ERIKSSON and HENNING (16) report the presence of both uredospores and teleutospores of P. glumarum in the pericarp of cereal grains. Several rusts have been shown to infect their host species through the seed. CARLETON (10) demonstrated this conclusively for the Euphorbia rust (Uromyces euphorbiae C and P) with the seeds of Euphorbia dentata. The plants grown from disinfected seed were always free from rust, while the controls were heavily infected, although planted in sterilized soil and protected by bell jars. MAssEE (25) states that P. malvacearum Mont. commonly enters young hollyhock plants through the seed. According to McALPINE (26) P. beckmanniae was introduced into Australia in 1903 and P. impatientis in 1904 through seed of Beckmannia erucaeformis and Elymus condensatus, pa uign aed received from the U.S. Department of Agriculture. Experimental evidence seems to indicate that rusts may infect cereals through the seed. When oats were introduced into Ecua- dor by growing European seed in the botanical garden at Quito, LAGERHEIM (21) reports that the plants became heavily .infected with P. coronifera, although neither this rust nor any of its aecidial hosts had ever been found in Ecuador. Carefully planned experi- ments, covering a period of years, were conducted by ERIKSSON (15) to determine whether P. glumarum winters in the seed of wheat 174 BOTANICAL GAZETTE [SEPTEMBER and barley. Glass cages of various sizes and types, provided with cotton ventilators to filter the air and caps to keep out the rain, were employed. Some were attached to a suction pump and arti- ficially ventilated; others, on all sides except the north, were fitted with double panes of glass, between which was passed a continuous current of water. Despite all these efforts to produce a normal environment for the plants, the air inside the cages was always 2—6° degrees hotter than the air outside, and the light considerably diminished. The plants were always abnormal, often attaining two or three times the height of their outside neighbors. In a few cases a single winter cereal plant was placed in each of several glass tubes early in the spring, long before any rust appeared outside. As a rule, however, seeds were planted in pots of steril- ized soil and placed in the bottom of the cages. As all the air entering the cages passed through cotton filters, no spores could be carried in from the outside. Although the majority of his results were negative, a considerable number of infections was obtained with both winter cereals and annuals. This he considered fully as much as could be expected, since the plants were grown under abnormal conditions. A similar set of experiments was planned by MAssEE (25), who planted wheat seed infected with P. rubigo- vera in two pots of soil and kept them covered with bell jars pro- vided with cotton wool filters. In one pot 26 per cent of the plants rusted, and in the other 47 per cent, while not a pustule appeared on the controls. The amount of rust developing in the grain field seems to vary somewhat with the date of sowing. Both the early and late grain, - according to Errksson and HENNING’s tables for the different cereals, are usually less rusty than those sown at an intermediate date. GaLLoway (17) called attention to this fact in 1893, when all his duplicate plots of grain, sowed ten days later than the originals, were free from rust. Moreover, he says, ‘‘ Examining the weather records for ten days preceding the rust, we find nothing to warrant the belief that the simultaneous appearance of the fungus the first week in May in widely separated spots was due to peculiar climatic conditions.” ERIKSSON’S well known mycoplasm theory was advanced to 1911] PRITCHARD—DISSEMINATION OF PUCCINIA 175 explain such cases. This theory is based chiefly upon the claim that rust apparently infects the cereal host. through the seed, although its mycelium is not recognizable in the germ by aid of the microscope and present cytological technique. KLEBAHN (20), for a time at least, supported this view, and even figured the nuclei of the fungus while in the mycoplasmic condition. The following experiments on the life history of P. graminis were made at the North Dakota Agricultural College and Experi- ment Station at Fargo, North Dakota, to obtain information which would aid in producing a rust epidemic yearly in our wheat breeding plots to test the strains selected for rust resistance. This is a spring wheat region, where the winters are exceedingly cold and consequently winter cereals are not grown. The germinating rusted wheat grains were studied at Madison, Wisconsin, under the direction of Dr. R. A. HARPER. Method All the plants used for inoculation, except when otherwise stated, were grown in the greenhouse in beds containing 6-8 inches of fertile soil. The grass plants were transplanted to pots and placed in the greenhouse several weeks before they were used. The temperature was kept reasonably cool, and the air fairly moist by frequently watering the floor. The inoculations were made by first mixing the spores of a pustule in a small quantity of distilled water. The plants were then moistened with distilled water by means of an atomizer and the spores applied with a camel’s hair brush. Except in a few cases where the plants were very large, they were kept under bell jars 24-48 hours. If they became dry, they were sprayed again the second day. Generally, however, they were quite moist when the covers were removed. For part of the work inverted test tubes attached to stakes at suitable heights were employed, the lower end being lightly closed with cotton wool. The test tubes were found to retain the moisture even better than the bell jars. Parallel marks were sometimes made on the leaves by means of India ink and the spores placed between them. The 176. BOTANICAL GAZETTE [SEPTEMBER beds containing these plants were generally watered just before making the inoculations, to provide a source of moisture for the air beneath the covers. When not stated, the height of the plants on which bell jars or test tubes were used varied from 8 to 13 inches, without straightening up the leaves. The wheat seedlings, grown from the rusted seed at Madison, Wis., and sectioned for study, were killed and fixed in Flemming’s strong solution, imbedded in paraffin, and stained with either iron-alum hematoxylin or the triple stain. Experimental investigations Experiments were begun to show how readily sporidia of P. graminis from wheat and native grasses infect the barberry, al- though there are very few barberry bushes in North Dakota, so few in fact that they could hardly be considered as a source of rust epidemics, unless miraculous powers were attributed to the wind in causing a widespread and uniform distribution of aecidio- spores. In the following experiments small pieces of dead straw, which were covered with teleutospores of P. graminis and had lain on the ground during the winter, were arranged parallel to each other and tied longitudinally on the branches of the barberry bushes (Berberis vulgaris), just as the buds were beginning to unfold in the spring. TABLE I INOCULATION EXPERIMENTS WITH TELEUTOSPORES OF Puccinia graminis Pers. Number of Date of : Number of ‘ a : Source of material branches Results experiment inoculation Secaukitedl Be es April 30, 1906 | Agr. ten.* 5 5 positive Oe Sy es April 30, 1906 | Agr. ten 7 I positive yO ee , 1906 heat 2 2 positive Ge es, April 30, 1906 | Agr. rep 2 2 positive $e ey April 30, 1906 | Whea | I I positive EE ce ea April 30, 1906 | Hord. jub 2 2 positive oo es April 30, 1906 | Ely. tri 2 I positive 1 Gas Sn eae April 30, 1906 | Wheat | I I posi Do Re es , 1906 | 3 3 negative * Abbreviations: Agr. ten.=Agropyron te : Age. th te repens; Hord. jub.= Hordeum jubatum; Ely. trit.= Elymus paola: oe vul. a Berberis vulga Tort] PRITCHARD—DISSEMINATION OF PUCCINIA 177 In experiments 5~13 inclusive, the inoculated barberry branches were heavily infected the 14th of May. Only spermagonia were present on this date, but they were frequently on both surfaces of the leaves. There were a few spermagonia on other parts of the bushes, but no such dense blotches as appeared where the rusty straw was applied. Further inoculations were made upon the barberry by scraping the teleutospores from dead straw, wintered the same as that described for Table I, and placing it on young buds or leaves which were carefully marked off by India ink and — These results are recorded in the following table. TABLE II INOCULATIONS MADE UPON Berberis vulgaris WITH TELEUTOSPORES FROM Puccinia graminis Pers. Nambarof | Date of | source of matrt | Number ts - pag 1G eo ee May 8, 1906 Oats to buds ., Io negative Or an May 9, 1906 Ely. trit. 10 buds 2 positive Drier mine May 21, 1906 | Ber. vul. 10 buds Io negative Mc eee eee May 22, 1906 | Wheat 8 leaves 8 positive S25 a ae June 26, 1906 | Ely. trit. I SS June 26, 1906 | Hord. jub. 1 leaf negative As shown by the table, these results were mainly negative, perhaps on account of poor germination, since the buds selected were fully as young as those used earlier. In order to obtain pure cultures of aecidiospores of known origin for further experiments relative to their infecting power, inoculations were made upon barberry bushes which had been standing in the greenhouse in large tubs for nearly a year and had borne no rust. The infections were made by tying small pieces of old rusty straw on the bushes in places offering the least oppor- tunity for contamination and moistening the straw frequently with distilled water. A summary of the results is shown in Table HI. Aecidia appeared only on parts of the barberry inoculated, and, with the exception of the rusty oat straw from which all my inoculations so far have failed, infections were obtained from each kind of material. This with the data of the two preceding 178 BOTANICAL GAZETTE [SEPTEMBER tables shows that under favorable conditions P. graminis passes readily to the barberry from wheat and certain grasses, viz., Agropy- ron tenerum, A. repens, Hordeum jubatum, and Elymus triticoides, confirming the general results of DE BArRy and others. TABLE Ii INOCULATIONS MADE UPON Berberis vulgaris WITH TELEUTOSPORES OF Puccinia graminis Pers. vical Bo eM | Source of material Method Results : ee, a ea March 29, ro67 | Agr. ten. Bell jar | Positive Pee ae eas March 29, 1907 | Agr. ten Bell jar Negative CR rs mmc ae ee March 29, 1907 | Agr. rep Bell jar | Positive Ys fieaeearas ee lacy oe March 29, 1907 | Agr. rep Bell jar | N Ree ols ee March 29, 1907 | Oats Bell jar | Negative Deon jh sess March 29, 1907 | Oats ell jar | Negative 1 RAC See A SE March 29, 1907 | Oats Bell jar | Negative ; Ee Pinar Gl March 30, 1907 | Wheat Bell jar | Positive is eens oss March 30, 1907 hea Uncovered = Negative IO March 30, 1907 | Hord. jub Bell jar Positive Sie eee March 30, 1907 | Hord. jub. Uncovered Negative LE Bea cena .....| April 4, 1907 eat _ Uncovered _ Negative PA a ee Oe / April 4, 1907 Wheat | Uncovered | Negative G | i Observations were made on the dissemination of rust from barberry bushes by taking note of the infection on the surrounding grasses. There was a small barberry hedge in Fargo very favorably located for this purpose, as it was surrounded on three sides by meadow and was heavily rusted every year. Careful observa- tions for three successive springs (1905-1907) furnished some sur- prising data. Early each year, the plants of Hordeum jubatum, Agropyron repens, and A. tenerum in the immediate vicinity of the hedge became thoroughly covered with the uredo stage, while Phleum pratense and Poa serotina were absolutely free from it, and Elymus virginicus bore only an occasional pustule. The rust was abundant within 25 yards of the barberry bushes, but practi- cally disappeared at a distance of 60 yards. The most persistent searching was required to discover a single pustule beyond 80 yards, and in no one of the three springs at this early date, before rust had begun to spread from the uredospores, could I find fresh uredo pustules of P. graminis beyond 100 yards from the barberry hedge, notwithstanding the fact that in 1905 rust was fairly abun- 1g1t] PRITCHARD—DISSEMINATION OF PUCCINIA 179 dant in this region. Either the aecidiospores are not borne as great distances by the wind as formerly supposed, or their ger- minative power is remarkably low. There is some additional evidence in support of the latter view. Plots of small wheat plants in the experimental garden were sprayed repeatedly with aecidiospores in the spring of 1905, yet scarcely any rust appeared until the plants were nearly two feet high, a fact commonly observed here in the field every spring, although volunteer wheat plants barely out of the ground in the fall are often covered with rust. Two series of infection experiments were made to obtain further data with reference to the spreading of P. graminis by means of its aecidiospores. From 98 aecidial pustules, taken at random in 1906, a total of 368 plants were inoculated. Plants of wheat, rye, oats, barley, and usually Avena fatua, Agropyron tenerum, A. repens, and Hordeum jubatum were inoculated from each aecidial pustule and covered with bell jars 24-48 hours. Germination tests of the spores, made by placing them in water and on wet filter paper kept in a moist chamber at 18-20° C., showed a via- bility of about 8 per cent. Rust appeared only on Avena fatua, Agropyron repens, rye, oats, and Hordeum jubatum. No plants of barley or wheat were infected. These experiments were repeated in 1907 by inoculating 247 plants from 13 pustules of known origin, the original host species always being included in each group. Tests of the spores showed about the same percentage of germination as those used in the former experiments. No barley plants were infected, and the only wheat plants which developed rust were those inoculated with a form which came originally from wheat. The aecidiospores of only 9 pustules, however, of the rrr used in the two series of experiments caused infection. This relatively low number of infections agrees with the results obtained by repeatedly spraying the wheat plots with aecidiospores in 1905, and may partly account for the confining of the rust to the immediate vicinity of the barberry hedge as observed for the three successive years 1905-1907. It is also in harmony with the very limited spreading observed by both MARSHALL and ScHOLER when they set barberry bushes in the . 180 BOTANICAL GAZETTE [SEPTEMBER grain fields, and might easily be accounted for by the change of host species if the heteroecism of the fungus is only facultative. A suspicion has frequently been expressed that the black rust spreads to the grain fields by aid of the grasses which either harbor the mycelium over winter or are infected early by aecidiospores. In order to determine the interval between the appearance of rust on grasses and cereals, the following observations were made in the spring of 1905. Rust the following summer, although not as abun- dant in North Dakota as in 1904, was still quite pronounced. TABLE IV FIRST APPEARANCE OF Puccinia graminis Pers. UPON GRASSES AND CEREALS AT Farco, NortH DAKOTA, IN THE SPRING OF 1905 dh Host species nate Location Remarks June 27. .' Hord. jub. Uredo Grass garden A few pustules on a single plant June 29..| Hord. jub. Uredo Near barberry July 6...) Spring wheat | Uredo . | Field Far removed from barberry July g....| Agr. rep. Uredo Near barberry | Present in abundance on : both Agr. ii = Hord. jub. Non d else- whee although. a diligent sear — made. July to...) Winter wheat*} Uredo Field Found i sh oi a at a . considerable distance from bar ushes. July 12...| Agr. rep. Teleuto | Near barberry Present on both Agr. rep. and Hord. jub. July 13...| Winter wheat | Teleuto Field Same ‘lot of winter wheat mentioned above. July 16 ..| Spring wheat | Uredo Field Ascoicine quite generally on all the oldest wheat. | * This was an experimental ge of winter wheat in charge of Dox n J. H. ie the agro mist, and the writer was not aware of its presence until July 10, when the plants which had avn the winter were thoroughly cov: er with mature uredo pustules of P. graminis, some Fadie old, the rust having first appeared probably ro—r4 days earlier. The foregoing table shows that P. graminis probably appeared upon the experimental plot of winter wheat almost or quite as early as upon Agropyron repens and Hordeum jubatum, even when the latter were in the immediate vicinity of the barberry. It also shows that, with the exception of the one case mentioned Igtt] PRITCHARD—DISSEMINATION OF PUCCINIA 181 under date of June 27, the uredospores of P. graminis were gen- erally present upon the spring wheat earlier than they were observed upon the wild grasses remote from the barberry bushes. In fact, P. graminis was present in the uredo stage upon spring wheat July 6, and with one exception could not be found upon the grasses remote from the barberry even July 9, after which date no further search was made for uredo upon the latter. Experiments were made to obtain data with reference to the spread of P. graminis from grasses to the wheat fields by means of the uredospores. Twenty-eight uredo pustules were selected from Agropyron tenerum, A. repens, Avena fatua, and Hordeum jubatum, and 230 plants inoculated. From each pustule inocula- tions were made upon plants of wheat, barley, rye, and oats, and upon the host species from which the rust was obtained. Parallel marks were made upon the leaves with India ink, and the spores placed between them in order to distinguish the results of regular inoculations from accidental infection. There was very little spreading of the rust, however, as the infected leaves were always removed from the greenhouse. The plants were covered with bell jars 24-48 hours, as formerly. Germination tests of the uredo- spores showed an average viability of 70-80 per cent. The uredospores of 21 of the 28 pustules caused infection, but showed a decided preference for certain host species. The rust readily infected rye, oats, and the grasses, but not wheat or barley. In fact, the results of the few experiments made seem to show what was anticipated from the two series of infection experiments with aecidiospores, viz., that one form of P. graminis is common to Hordeum jubatum, Agropyron tenerum, A. repens, Avena fatua, oats, and rye, but is incapable of infecting either barley or wheat. This furnishes little encouragement to those who believe that P. graminis is spread to the wheat fields from the barberry bushes or from occasional protected spots, as beneath ice by aid of the native grasses. The data however give no information with respect to the forms of P. graminis on wheat or barley, as neither was infected, but in our breeding experiments in 1905 a number of wheat plots were surrounded by a border of barley which was practically destroyed by black rust, and yet there was no visible 182 BOTANICAL GAZETTE [SEPTEMBER evidence that it ever spread to the wheat. Hence it appears that the forms upon these two species are distinct. The wintering of P. graminis as mycelium in plant tissues in North Dakota is extremely doubtful, as there are no winter cereals and the uredo stage does not appear upon the grasses until very late in the spring, when they are quite large. To test the supposi- tion, however, that the fungus might pass the winter in occasional plants under shelter and produce a new outbreak of uredo the fol- lowing season, I placed heavily rusted plants of Agropyron tenerum, A. repens, Hordeum jubatum, Elymus virginicus, and E. canadensis in large pots three successive falls (1904-1907) and transferred them to the greenhouse where they remained until summer, but no fresh uredo pustules ever appeared on any of them. Furthermore, in collecting data relative to the appearance of P. graminis upon cereals and grasses in the spring of 1905, a piece of low meadow containing Hordeum jubatum, Agropyron tenerum, and A. repens, which was flooded by the city in the winter and used as a skating pond, was carefully observed, but no uredo pustules appeared here until they were found on the grains and grasses elsewhere. The origin of spring infections has frequently been attributed to over-wintered uredospores, although this is merely a hypothesis. In order to determine with some accuracy the duration of the ger- minative capacity of the uredospores of P. graminis, the following experiments were made. Bundles of rusty straw which ha stood in the shock until late in the fall of 1904 were placed on the ground. Others were tied to trunks of trees, and some stored in the attic of one of the college buildings, where the temperature was below freezing but much warmer than the outside atmosphere. Rusty wheat straw was also put in manila envelopes and in test tubes, and these laid in pasteboard boxes on the ground. All the material placed upon the ground was covered by snow the greater part of the winter. To still vary the conditions, test tubes of rusty wheat straw were attached in an inverted position to stakes out- side, 2-3 feet above the ground, while packets were buried in ice at the ice house and others kept in the laboratory. From the middle of September to the following July germination tests of the uredospores were made once a week from all these sources. At tort] PRITCHARD—DISSEMINATION OF PUCCINIA 183 the beginning of the experiment, about 10 per cent of the uredo- spores were viable, but by the end of September this had dwindled to 2 per cent; and only an occasional uredospore germinated in October and none whatever after November 15. Some confusion arose at first over a fungus whose hyphae emerged from the germ pores, but without showing any con- spicuous evidence of its entrance. This fungus proved to be an Alternaria, which parasitized many uredospores. Repeated attempts were made to germinate uredospores from Hordeum jubatum and occasionally from Agropyron repens which were buried under ice and snow, but always without success. Old uredospores can be obtained in abundance all winter and in early spring on Hordeum jubatum, lying between the stem and sheath, but it is practically impossible to find them here on other grasses in winter, although the plants may be buried under ice in low places, as they drop off before winter and are replaced by teleutospores. Hence no uredo pustules were available from other grasses except Agropyron repens, whose few winter-borne uredospores would not germinate. The germination tests show that during the winter of 1904-1905 in North Dakota all or practically all the uredospores of P. graminis probably lost their viability, and hence were not the cause of the large amount of black rust in the state the following summer. The annual reappearance of P. graminis in Kansas, Nebraska, and the Dakotas has often been explained by assuming that it passes the winter in Texas and spreads north by means of the wind and growing crops. To obtain data on this point an endeavor was made to catch uredospores of P. graminis from the air before any pustules appeared upon the wheat. A post 5 feet high was set in the edge of a wheat plot and a soup dish 7 inches in diameter, containing a small quantity of distilled water, just enough to fill one tube of the centrifuge, was exposed at its top 30-40 minutes. The whole inner surface of the dish was rinsed with the water to collect any spores adhering to its sides. The water was then poured into a tube provided with a tapering bottom, and the débris precipitated by means of a centrifuge. All the particle- bearing liquid was removed from the narrow end of the tube by 184 BOTANICAL GAZETTE [SEPTEMBER means of a pipette, placed upon six slides and examined micro- scopically. This process was repeated two or three times a week for nearly a month, but no uredospores of P. graminis were caught until uredo pustules were abundant on the surrounding wheat. Further observations were made to determine whether uredo- spores are commonly borne very great distances by the wind. On a piece of ground one-third to one-half acre in area, which we used for breeding rust-resistant wheat, a rust epidemic was produced every year. This was accomplished by plowing into the soil rusty wheat straw and spraying the wheat repeatedly with aecidio- spores of P. graminis tritici Erik. and Henn. It should also be mentioned that our original seed, the foundation stock, was obtained from the badly rusted crop of 1904. Hence there were present teleutospores, aecidiospores, uredospores, and probably infected seed. For the present, however, we are concerned only with the fact that rust annually appeared upon these plots in great abun- dance. In fact it was almost impossible to obtain any plump kernels of wheat from plants grown here. During at least two summers (1906-1907), when these plots were thoroughly covered with P. graminis, there was scarcely any rust on the field plots of wheat which lay a short distance north of the infested area and in the direction of the prevailing winds, although the latter passed over the breeding plots, often causing considerable annoyance while I was taking rust notes. The only possible hindrance to the passage of the spores was a few rows of shrubs covering a strip about 10 feet wide, thinly planted and varying from 6 to 8 feet in height, located 20-25 yards from the rust bed. However, there was a road about 20 feet wide running north and south through the shrubbery and along the west edge of the infested area. Hence there was ample opportunity for wind distribution of the uredospores, and former experiments have shown that they were highly viable during the summer of 1906, yet practically no rust appeared upon these neighboring wheat plots. The fact that P. graminis does not appear upon wheat in North Dakota in the summer until the plants are nearly 2 feet high, several weeks after the wheat crop is harvested in Kansas and Nebraska, rgtt] PRITCHARD—DISSEMINATION OF PUCCINIA 185 would also appear to indicate that the spores are not commonly borne very great distances by the wind. Little or nothing has been done in the past to test the possible infection of sprouting cereals by means of germinating teleuto- spores from the soil. When buried in moist earth it is not even known whether teleutospores can produce germ tubes or promy- celia. A striking fact in connection with the possible infection of seedlings by teleutospores was observed in our field work. Our breeding ground, in which we produced an abundance of rust annually as described above, consisted in 1907 of three parts which, however, were nat separated by paths or any visible marks. The whole west half had grown three successive crops of rusted wheat (1905-1907); all the east half except a narrow strip on the north end grew rusted wheat in 1905 and 1907, but produced a crop of flax in 1906; the remainder was in sod until 1907, when it was planted to wheat. The rusty wheat instead of being removed from the ground was always plowed under. The same varieties, except some of Farrer’s wheat which was not taken into account, were planted on all three areas at the same dates. The soil was equally level and very fertile. All the wheat was inoculated alike during the spring and summer of 1907, yet shortly before harvest the three parts were separated quite distinctly by lines of rust demarkation, the amount of rust varying with the number of crops of rusted wheat grown upon each area. Whether these results are due to the different quantities of teleutospores in the soil of the different areas or not cannot of course be definitely stated, but they are at least suggestive of the need of further experiments in this direction. If the perpetuation of the wheat rust in the absence of the barberry is due to the teleutospore infection of the germinating seed, variation in the time of seeding might easily account for the annual variability in its prevalence. The further possibility that rust may be carried in the seed itself is certainly also to be considered. Teleutospores and myce- lial fragments of P. graminis are often present in abundance in the pericarp of wheat grains, and can frequently be recognized by the appearance of pustules, as will be described later. Early in the spring of 1905 about 60 wheat grains with such contamination 186 BOTANICAL GAZETTE [SEPTEMBER were planted under each of two glass cages provided with cotton ventilators to prevent the entrance of spores from the air. The experiment was afterward repeated in the greenhouse, but rust never appeared on the plants in either case. The conditions however were exceedingly abnormal. The ventilators were entirely too small and the moisture inside the cages was always excessive. While the plants grew rapidly, headed, and_blos- somed, they failed to set seed both years. Another experiment made in the spring of 1905 appeared to give more favorable results. Wheat was sowed at various dates, some of it quite late. It was all inoculated early and repeatedly with both aecidiospores and uredospores of P. graminis tritici Erik. and Henn., the latter being obtained chiefly from the experimental plot of winter wheat of the same source as noted above, but the wheat of every sowing remained nearly free from rust until it began to head, when each in turn became thoroughly rusted. It might be assumed on this evidence that wheat has only a definitely limited period of sus- ceptibility, still very small volunteer wheat plants are often quite rusty in the fall. It is possible to attribute this peculiar behavior to infection through the seed with a long subsequent incubation period in the growing plant, although the possibility of its coming through the soil is not excluded. The infection of wheat grains with P. graminis can often be recognized by the presence of a tiny black spot where the grain separated from the mother plant. When black, this area is gen- erally filled with teleutospores, which can be distinguished in mass with the naked eye or at least with the aid of a hand lens. Such grains are usually shrivelled, but occasionally they remain quite plump. Grains showing a spot of larger area with somewhat irregular boundaries are usually infected with other fungi, as Alternaria or Helminthosporium, and may not even contain rust. These are the so-called ‘‘black-points”’ mentioned by BoLLEy.‘ In rusted grains of wheat the pustules are usually most abun- dant in the thick portion that was formerly attached to the rachilla, but they are also found in other parts of the pericarp, and often lie in the seed coats where they are pressed against the endosperm 4 Science, Oct. 21, 1910, p. 1. 191i] PRITCHARD—DISSEMINATION OF PUCCINIA 187 or embryo. As many as to pustules are sometimes seen in a single section, and nearly all of them are wholly inclosed by the tissues. All about the pustules are masses of rust mycelium, but the hyphae are not confined to these areas. They extend con- siderable distances from the pustules, and are present in numerous grains in which teleutospores cannot be found. To obtain further information relative to infection through the seed, badly rusted grains of wheat after germinating from one day to two weeks were studied in the botanical laboratory at Madison, Wis., by means of cytological methods. The seed avail- able was a remnant of former experiments, 4 or 5 years old, and revealed some very interesting phenomena. Teleutospores in certain pustules, lying in the region of the hilum, were found to be undergoing remarkable changes, resembling the so-called palmella formations of certain filamentous algae. The protoplasts appeared to grow and divide in various directions, often distending the walls until they became quite thin (figs. 5-13). The nuclei, though not well fixed, were present as irregular densely stained bodies. Frequently one or both cells of the teleutospore were still undivided (figs. 1-3, 15), but numerous later stages were present, in which the protoplast had divided one to several times. As a rule, the wall between the two original cells was quite thin and persisted for some time (figs. 5, 6, 8), but occasionally it could not be distinguished (fig. 7).. In the latest stages observed the cells became more distinct, often rounding slightly and acquiring thicker walls (figs. 7, 8, 11, 12). A view of the apical end of the teleutospore represented by fig. 12 is shown in a lower focus in fig. tr. In numerous cases the two halves of the former teleuto- spore finally separated from each other, forming two more or less globular multicellular aggregates (figs. 13@, 18). That these conditions are due to a parasitic mycelium, which has penetrated the teleutospores and completely replaced the protoplasts of the rust, is of course a possibility to be reckoned with. As is seen from the figures, however, direct evidence of the presence of such a parasite is entirely lacking. There is no mycelium outside the rust cells, and no evidence of a gradual absorption and replace- ment of the rust protoplast by that of a parasite. The subsequent 188 BOTANICAL GAZETTE [SEPTEMBER behavior of the cells will of course show their true nature, but as material is not available for following them through the later stages of germination of the seedling, it seems best to publish as a preliminary account the figures of the stages already found. The importance of their bearing on a possible method of wintering of wheat rust in the absence of the barberry or uredo is apparent. These peculiar phenomena were not confined to the teleuto- spores, but were frequently present in the stalk cells (figs. 2, 5, 9, 10), and even in the mycelial region below (figs. 14, 15). Fig. 14 represents a radial section through the base of a pustule, one teleutospore and neighboring stalk cells being included. As is seen, the growing cells of the sorus were associated more or less in groups, but usually interspersed with smaller empty cells. Sometimes they formed dense areas, where it was difficult to determine whether they were of hyphal or teleutosporic origin. Now and then faint outlines resembling distorted, multicellular teleutospores were seen in the mass, but in all probability at least some of the cells arose from the mycelium. Apparently identical cells were found in other parts of the pericarp remote from the pustules (fig. 17). Lying near were filaments composed of similar though usually smaller cells (figs. 16, 17, 19). These however were enlarged portions of a smaller mycelium, all the remaining cells being empty. Quite separate from the cells just described, fragments and often considerable pieces of what appeared to be living rust mycelium were found mixed with dead hyphae of the rust (figs. 20-22). They were usually in the pericarp, but often lay next to the deepest layer. There were occasional places outside the region occupied by the layer of feeding cells where they passed through into the cells of the scutellum and were found in considerable abundance within 6 or 7 cells of the growing plant itself (fig. 21). As noted, the fate of the teleutosporic and mycelial cells described above remains for future determination, as my present material contains no later stages. The evident suggestion is that they may serve as growing points for the development of new rust mycelia and the infection of the embryo and seedling. The possibility for infection of the seedling when the pericarp tgit] PRITCHARD—DISSEMINATION OF PUCCINIA 189 of the seed is filled with living rust would seem to depend chiefly on the presence of reserve food for the fungus and the capacity of the hyphae to grow through a few dead cells. The penetration of the dead tissue may and probably does offer some difficulty to the majority of the hyphae, but in some places only a single cell wall of the pericarp intervenes, which could scarcely be looked upon as an absolute obstruction. At any rate, an abundance of mycelium resembling rust was found in the scutellum close to the growing tissue, with apparently nothing to hinder its further progress in that direction. Whether after infection of the embryo in the manner suggested therust mycelium might grow with the plant and take on a virulent form at later stages, when it spreads to form pustules, is certainly an interesting possibility. Such a general systemic infection was assumed in ErRrksson’s mycoplasm theory, and there is some evidence in the general behavior of the rusts as noted above to suggest such a possibility. That such a palmelloid growth of fungal hyphae under peculiar conditions of nutrition is to be expected is abundantly shown by Racrgorskt’s interesting obser- vation on a palmella-like growth of Basidiobolus when placed in media rich in nitrogen. Further investigation of the infection of wheat by rust through the seed will be made when suitable material is obtained. Summary 1. Puccinia graminis passed readily from wheat, Agropyron tenerum, A. repens, Hordeum jubatum, and Elymus triticoides to the barberry. 2. Observed facts seem to oppose the theory that aecidiospores and uredospores are carried considerable distances by the wind. 3. Uredo pustules of P. graminis appeared upon the experi- mental plot of winter wheat as early as upon grasses near the bar- berry bushes, and with one exception were generally present upon the spring wheat earlier than they appeared upon the grasses remote from the barberry. 4. P. graminis does not appear to spread to the wheat fields by aid of the grasses. The few experiments made seem to show three distinct biological forms of this fungus: one for wheat, one Igo BOTANICAL GAZETTE [SEPTEMBER for barley, and one for rye, oats, Hordeum jubatum, Agropyron tenerum, A. repens, and Avena fatua. 5. Uredospores of P. graminis failed to survive the winter of 1904-1905 at Fargo, North Dakota. 6. The wintering of P. graminis as mycelium in plant tissues in North Dakota is very doubtful, as shown by the late appear- ance of the uredo pustules in the spring and the failure of rusted grasses to produce the uredo again after being housed during the winter. 7. The pericarp of rusted wheat grains is frequently filled with rust mycelium and numerous pustules of teleutospores. 8. Teleutospores in some of the germinating grains appeared to be germinating in a palmella-like stage. g. Pieces of mycelium resembling rust were found in the cells of the scutellum close to the growing plant. In conclusion, I wish to acknowledge my indebtedness to Dr. R. A. Harper for aid in the cytological study of the material and in the preparation of the paper. UNIVERSITY OF WISCONSIN ADISON, WIS. LITERATURE CITED 1. Barctay, A., Rust and mildew in India. Jour. Bot. 30:—. 1892. 2. Bary, ANton De, Recherches sur le développement de auelaiie champig- nons parasites. Ann. Sci. Nat. Bot. IV. 20:—. 1863. . —, Neue Untersuchungen iiber die Crednien: insbesondere die Entwicklung der Puccinia graminis und den Zusammenhang derselben mit Aecidium Berberidis. Mon. Ber. Akad. Wiss. Berlin. 1865. , Neue Untersuchungen iiber Uredineen. Mon. Ber. Akad. Wiss. Be "1866. 5. BLAcKMAN, V. H., On the conditions of teleutospore germination and of sporidia formation in the Uredineae. New Phytologist 2:10. 1903. 6. Bottey H. L., ey rust; is the infection local or general in origin? Agri. Sci. 5: 263. 7. ———, Rust nae etc. N.D. Agr. Exp. Sta. Bull. 68. 1906. 8. Beevetp, Oscar, Untersuchungen aus dem Gesamtgebiete der Myko- logie 14:154. I g. CARLETON, M. A., Coreal rusts of - United States. U.S. Dept. Agric., Div. Veg. Phys. and Path., Bull. 1899. 1git] PRITCHARD—DISSEMINATION OF PUCCINIA IQI Io. Lal al Lal w CARLETON, M. A., Investigations of rusts. U.S. Dept. Agric., Bur. Pl. Ind., Bull. 63. 1904 - CuRIstMAN, A. H., Observations on the wintering of grain rusts. Trans. Wis. Acad. Sci. 15:08. - Coss, N.A., Cube e an economic knowledge of Australian rusts. Agr. Gaz. NSW. 744. 1892. . Errksson, Jacos, Vie erie et plasmatique de certaines Urédinées. Compt. Rend. 124:475. er heutige He der Getreiderostfrage. Ber. Deutsch. Bot. Gesclls, 15:183. 1897 5 , our orgie et la propagation de la rouille des céréales par la semence. Ann. Sci. Nat. Bot. VIII. —:14, 15. 1902. (Contains a plate of illustrations of the special corpuscles.) - Eriksson, J., and HENNING, Ernst, Die Getreideroste, ihre Geschichte und Natur, sowie Massregeln gegen dieselben. Stokholm. 1806. - GatLoway, B. T., Experiments in the ae of rusts affecting wheat and other cereals. Jour. Mycol. 7:195. - Kienttz-Geruorr, F., Die Gonidien von ei clavariaeforme. Bot. Zeit. 46: 388. - Kiepaun, H., Die ious tes Rostpilse. Berlin. l 190 ————, Einige Bemerkungen iiber das Mycel des pS Ber. Deuiach. Bot. Gesells. 22:255. 1904. (Contains two figures - Lacernerm, G., Ueber das Vorkommen von europiischen Vedieen auf der Hochtbene: von Quito. Bot. Centralbl. 54:324. 1893. (Jour. Mycol. 7:327. Mies ) - Loverpo, J., Les maladies cryptogamiques des céréales. Paris. 1892. . Mateos P., Ueber das Auftreten der Stylosporen bei dem Uredineen. Ber. Deutech. Bot. Gesells. 9:90. 1891. Marsuatt, Rural economy of Norfolk. Ed. 2, London. 1795. p. - Masser, G., The cereal rust problem; does Errksson’s mycoplasm ani in nature ? wee Sci. D. 337. 1899. - McAtprne, D., The rusts of Australia. 1906. ; PLowRIcHT, C. B., Can wheat ins propagate itself apart from the barberry? Gard. heron: Sept. 9 , A monograph of the British Uicanes and Ustilagineae. Lon- don. 1 . SCHOLER, 'N. P., “Berberissens skudeliger Indflydelse paa Soeden. Landockomminske Tidender (1818). part 8, p. 289. Nielson, Ugeskrit for Landmoeda. 1884. - Situ, W. G., Corn mildew. Gard. Chron. II. 21:—. 1884. . Tuten, F, Vv, Mitteil. aus dem forstl. Versuchswesen Oesterreichs. as 1879 - Warp, H. Illustrations of the structure and life history of Puccinia graminis. in Botany 2:229. 1888. 192 BOTANICAL GAZETTE [SEPTEMBER 33. WITHERING, W. A., Botanical arrangement of British plants. Ed. 2. Vol. 1.3787. 34. ZUKAL, H., Untersuchungen iiber die Rostpilzkrankheiten des Getreides in Oesterreich-Ungarn 10:16. 1goo. EXPLANATION OF PLATE IV Phenomena appearing in the mycelium and Plein of Puccinia graminis in rusted grains of wheat during germination Fics. 1, 2.—Teleutospores, showing thin walls aa cells preparing for division; fig. 2 also shows an enlarged distorted stalk cell in which a cell wall has been formed. Fic. 3.—A teleutospore whose lower cell has divided. Figs. 4-6, 9, 10.—Early palmella-like stages, showing angular cells with thin walls. Fics. 7, 8, 11, 12.—Late palmella-like stages, in which the cells are more or less rounded, thicker walled, and less crowded. IG. 13.—A group of teleutospores lying in the edge of a pustule that was sectioned somewhat obliquely. Fics. 14, 15.—Radial sections through the base of pustules showing living cells of the sorus Fic. 16.—Mycelium lying in the pericarp; a few cells were alive and considerably enlarged, while the remainder of the filament was dead. IGS. 17, 19.—Dividing cells and living portions of mycelium lying in the pericarp remote from pustules; as in fig. 16, only a small portion of each filament was alive. : Frc. 18.—A group of cells found among the teleutospores of a pustule similar to that represented by fig. 13 (cf. 13a). ; Fics. 20, 22.—Fragments of mycelium found in the pericarp mixed with dead hyphae of the rust. Fic. 21.—A typical piece of mycelium found in the scutellum within 6 and 7 cells of the radicle. PLATE IV BOTANICAL GAZETTE, LII ate ES FO ige eae oi —emhie ee at CAZES 20 j PRITCHARD on PUCCINIA GRAMINIS EVAPORATION AND PLANT SUCCESSION: CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 147 GrorcGe DAMON FULLER (WITH SIX FIGURES) The plant associations on the sand dunes of Lake Michigan have been described by Cowtes (1), who has called attention to the succession which is here so strongly marked and so easily deter- mined. In much of the region immediately south of the lake, the forest succession consists principally of associations dominated respectively by cottonwood, pine, black oak, white and red oak, and beech in the order named. These are usually designated the cot- tonwood, pine, and oak dunes, and the oak-hickory and beech- maple forests. They represent the major associations in a succes- sion extending from the pioneer trees to the climax mesophytic forest formation of the region. The dynamic physiography and the details of the composition of the various stages in the succession have been so thoroughly discussed by Cowtes that little further elucidation is necessary, but hitherto no attempt has been made to obtain any quantitative determination of any of the factors influ- encing this succession. The researches of LrvincsTon (2) and others have shown that the evaporating power of the air is a rather satisfactory summation of the atmospheric factors which determine the growth of plants during that portion of the season free from frost, and that it can be accurately measured by the porous-cup atmometer; accord- ingly, in the spring of rgro, a number of observation stations were established upon the sand dunes near Millers, Ind., and the rate of evaporation was determined during the ensuing growing season. Both the porous-cup atmometer devised by LrvincsTon (3) and the type described by TRANSEAU (4) were employed in this investi- gation. They were mounted in wide-mouthed bottles having a * A preliminary report of evaporation studies in the plant associations upon the sand dunes of Lake Michigan. 193] [Botanical Gazette, vol. 52 194 BOTANICAL GAZETTE [SEPTEMBER capacity of 500 cc., closed with tightly fitting cork stoppers that were perforated for the atmometer tubes and for bent capillary glass tubes which served to equalize the atmospheric pressure within the bottles with that of the exterior air, without causing any loss by evaporation or permitting rain water to enter the reservoir. The bottles were sunk in the soil about two-thirds of their height, so that the evaporating surface of the instruments was 20-25 cm. above the surface of the soil. Except where otherwise specified, the readings were made weekly by filling the bottles from a gradu- ated burette to a file scratch on the neck. The small area of the water surface at this point made the probable error in readings less than +0.5 cc., and this could have had no appreciable effect upon the results. The instruments were all standardized to the same unit before being used, restandardized at intervals of 6-8 weeks during the season, and a final correction made on their being collected in the autumn. By the coefficients thus obtained all readings were reduced to the standard adopted by LivincsTon (5) in his recent paper on the operation of the porous-cup atmometer. The directions given in that article were so closely followed that it is unnecessary to detail further the methods used in operating the instruments. Two or three atmometers were discarded during the season on account of various irregularities in their operation, but others either maintained a uniform rate of water-loss or showed a variation that progressed uniformly at a readily calculable rate. To provide still further against the possibility of serious error, two instruments were often maintained a few feet apart at the same station, and several stations were usually established in the same association, the mean of the various readings being taken as giving the true measure of the evaporating power of the air for that asso- ciation. | No correction has been made for errors caused by rainfall, although during showers some water undoubtedly passes through the porous cup and into the reservoir, because it was thought that the amount of variation thus produced would be the same for all stations within so limited an area, and hence the comparative rela- tion of results would remain unchanged. This assumption has been largely verified by Brown (6), using an atmometer with a rain- 1g1t] - FULLER—EVAPORATION AND SUCCESSION 195 correcting valve. It is the intention of the writer, however, to employ this improved atmometer, also devised by LivincsTon (*7), in the continuation of these studies. Fifteen different stations were established in the various asso- ciations, care being taken to select spots which possessed the average amount of tree, shrub, and herbaceous vegetation characteristic of that specific association as a whole. Owing to a variety of accidents and other circumstances, all the stations did not give equally satisfactory and continuous records; hence the present preliminary report is confined almost entirely to the results from Io stations in 4 different associations. Many of these records extend from May 6 to October 31, or over a period of 178 days; at other stations the record begins at a somewhat later date, but continues until the severe frosts of November 1, and includes the important part of the growing season for all except a few very early spring plants. In order to facilitate comparisons between the various stations, and to exhibit the progress of the evaporation rate during the entire season, the average water-loss per day between the weekly readings has been calculated, and the results expressed in graphs with ordinates representing the number of cubic centimeters lost per day by a standard atmometer, the abscissae being the intervals between the weekly readings. The readings included within each calendar month are indicated at the top of the diagram. For con- venience of reference, the stations are numbered consecutively, beginning with that nearest the lake shore. The first group of stations was upon some slowly moving dunes directly north of the village of Millers, Ind., and between the southern shore of Lake Michigan and the Grand Calumet River. According to old maps, this river formerly discharged its waters into Lake Michigan very near the spot selected for one of these stations. Any such discharge has long since ceased, and its exact location has been entirely obscured by the advancing dunes, leaving the remaining river bed as a shallow channel in which the water has little or no current, the present discharge being some eight miles farther west. Dunes are now advancing into this channel at several points, and within a few years will doubtless occupy other portions 196 BOTANICAL GAZETTE ; [SEPTEMBER of its bed. Here, at a distance of too to 200 meters from the shore, the pioneer tree association becomes established, and persists upon dunes of variable size that are usually more or less actively moving. This association is characterized by a paucity of species, all having strongly xerophytic structures. Populus deltoides, Salix glau- cophylla, S. syrticola, Prunus pumila, and the two grasses Cala- movilfa longifolia and Ammophila arenaria are at this point the only conspicuous members of this rather open cottonwood dune association. In it, upon dunes that have become almost com- pletely fixed, two stations were established on May 6, and a third on July 9, and at the three stations at least four instruments were maintained in constant operation until the last day of October. These stations were about 200 meters from the lake shore, some too meters apart, and about 12 meters above the level of the waters of Lake Michigan. At all stations the atmometers received a small amount of shade for a few hours of the day, and on account of the _ open nature of the association were little sheltered from the wind, the cups receiving a rather sharp sand blast during high winds. Station no. 1 had some sheltering groups of cottonwoods on a slight elevation of sand a few meters southeast of the instruments, and no. 3 possessed a similar but smaller shelter at the southwest. These differences of exposure to winds probably caused some of the variations in the records of the different stations, but affected _ very slightly the average rate for the season. e graphs for three cottonwood dune stations have been plotted upon the same chart (fig. 1), and exhibit a great similarity in their general course and in their simultaneous maxima and minima. The rainfall at Chicago (20 miles distant) for the same period, expressed in centimeters, is shown for periods corresponding with those of the intervals between the evaporation readings, but as there seems to be no very exact correspondence between the amount of precipitation and the amount of evaporation, these data are omitted from the other charts. There is certainly a corre- spondence between the number of hours of cloudy or rainy weather and the amount of evaporation, but this has not been exactly determined, nor does it seem important in our present studies. The evaporation graphs indicate that the most critical period occurs © 1gIt] FULLER—EVAPORATION AND SUCCESSION 197 about the end of July, and this is also toward the end of a period of seven weeks with very little rainfall; hence it may be safe to assume, even without any direct data regarding soil-moisture, that a JUNE JULY AUGUST SEPTEMBER} OCTOBER Cd, 5 tale | | | [ | / a [i_ i a [ Lyi l\\ \ L\\ Wy (2ay/ 13) itt Vi\ A Weal 2 I [Vl Veli} : Wi “LIT A \\ | \ \ | i \ VA\\ | \ ie i\ { \\ | = iW! \ ae main \ \ ji ia } LV] \ ae all lf x N Me UI ff \ i | \{\ 3 | \| \ \ bod oy 10; Hj} | | | | Weekly rainfall on Bae ee ig +——+-—-—4 incom. fee eee ee Per aw Be nae rm Fic. 1.—Evaporation rates in the cottonwood dune association at stations nos, I, 2, and 3. 198 BOTANICAL GAZETTE [SEPTEMBER at this time there is a maximum demand by the atmosphere upon the water contained in the plant tissues, while at the same time only a minimum supply is available to replace such losses by transpiration. Two other periods of high evaporation are found to occur, one late in June and the other early in September. The latter is doubtless the one of greater stress, for it follows a month of very low rainfall. It will be seen that the maximum average evaporation for any week is just above 35 cc. per day, and that the minimum only once falls below to cc. per day. The average rate for the three stations upon the cottonwood dune for the 178 days of observation is 21.1 cc. per day. The graphs (fig. 1) indicate that not only is the cottonwood dune an association with a very high rate of evaporation, but also that it is subject to excessive variation. This is most noticeable during May and June, but to a less marked extent prevails through the season, the fluctuations being decidedly greater than in the other associations (fig. 4). The mean of the readings of these three stations is believed to express most accurately the true measure of the evaporating power of the air during the growing season in the cottonwood dune association, and is therefore plotted and used in comparison with similar graphs from the other associations (fig. 4). As the dunes gradually beeoiks fixed, an association dominated by evergreens succeeds the cottonwood dune. This pine dune asso- ciation varies somewhat in composition in different localities, but in the area under consideration is dominated by Pinus Banksiana, associated with Juniperus virginiana, J. communis, and in the older portions containing also Pinus Strobus. In the undergrowth Arctostaphylos Uva-ursi is conspicuous, associated with Rhus canadensis, R. toxicodendron, Prunus virginiana, Celastrus scandens, seedlings of Quercus velutina, Smilacina stellata, Asclepias tuberosa, Monarda punctata, and other woody and herbaceous plants. Two stations were placed in this association at spots of medium density of growth about 1oo meters south and east of the cottonwood dune series, but owing to several accidents only one record is worth reporting. This, from station no. 4, is unbroken for 178 days, and is often the mean of the readings from two atmometers. tort] FULLER—EVAPORATION AND SUCCESSION 199 This association is unique in the dominance of conifers, but is also notable for the comparative abundance of its undergrowth, although many species have decidedly xerophytic characters. That it is a comparatively short-lived association is evident from the presence of seedlings of Quercus velutina, the dominant tree of the succeeding association, very early in its history. Comparing the graph of its evaporation with that of the cottonwood dune (fig. 4), it will be seen that it is much lower, never reaching 20 cc. per day, and is subject to less violent fluctuations. Its maxima and minima are nearly synchronous with those of the cottonwood dune. The maximum evaporation rate is 17.5 cc. per day, the minumum falls below 4 cc., and the average for the season of 178 days is 11.3 cc. daily. Proceeding inland from the lake shore, the pines gradually decrease in numbers, and the black oak, Quercus velutina, becomes more plentiful, until at a distance of about 500 meters south of the last station it forms an almost pure stand with only occasional trees of white oak, Quercus alba. The shrubby undergrowth con- sists principally of Prunus virginiana, Rosa blanda, Viburnum acerifolium, Vaccinium pennsylvanicum, Ceanothus americanus, and seedlings of Quercus velutina and Q. alba. Among the herbaceous members of the association are Smilacina stellata, Lupinus perennis, Tephrosia virginiana, Lithospermum canescens, Asclepias tuberosa, Helianthemum canadense, Polygonella articulata, and Aster linarii- folius. In this oak dune association four stations were placed within a range of 100 meters; no. 6, on a fixed dune 15 meters high, well covered with the oak forest; no. 7, on a slope at an altitude of about 8 meters; and nos. 8 and 9, on the general floor of the forest some 5 meters above the level of the lake waters. All were about equally exposed and shaded. No. 6 was established on May 6, and the other stations on May 26. Station no. 9 was subject to so many interruptions that no report of its evaporation is presented, but the graphs from the other three (fig. 2) show a very close agree- ment, with differences corresponding directly to their elevation. A maximum of nearly rg cc. per day occurred in May during the second week of the record, before the trees were in full foliage. The absence of leaves would largely account for this excessive rate, 200 BOTANICAL GAZETTE [SEPTEMBER but as it occurred when only one instrument was recording, it may be regarded as lacking confirmation, and as it could hardly be a critical period on account of the abundant water supply in the soil, it is disregarded in the general discussion. Throughout the re- mainder of the season the rate is rather high, but not subject to great fluctuations. A minimum of about 5 cc. per day is reached in September, and is followed by a distinct rise as defoliation pro- MAY JUNE JULY AUGUST {SEPTEMBER} OCTOBER a Ab 2 = RSA ia ~ I ie \\ VAN | VAN —) 7 ne Att \ Ng SSMT/NE fi \ } = ae : N/ Fic. 2.—Evaporation rates in the oak dune association at stations nos. 6, 7, and 8. gresses. Station no. g (not plotted) gives a somewhat higher rate during July, affording a maximum for that month and for the sum- mer of 16 cc. per day. The average rate for the whole period is 10.3 cc. per day. The mean of all stations in the oak dunes is used (fig. 4). in comparison with similar graphs from the other asso- clations. At Millers, Ind., the vegetation exhibits no undisturbed ‘suc- cessional stages beyond the oak dune, but 15 miles farther east, near the village of Otis, Ind., there is a tract of the climax deciduous 1911] BS ULLER—EVAPORATION AND SUCCESSION 201 mesophytic forest dominated by the beech, Fagus grandifolia, and the maple, Acer saccharum. These two species form at least 85 per cent of the tree growth, with the remaining 15 per cent com- posed of Tilia americana, Ostrya virginiana, and Prunus serotina, and occasional trees of Quercus rubra, Platanus occidentalis, and Liriodendron Tulipifera. The undergrowth is largely seedlings of the dominant tree members of the association, together with Cornus alternifolia, Viburnum pubescens, Asimina triloba, Sambucus race- mosa, and such herbaceous forms as Trillium grandiflorum, Dicentra JUNE JULY AUGUST |SEPTEMBER ocroser | 2 j BS VATA | 3 NY YI | = ie | Ne \N / y AG T/T} M1 \ \ vs Bee ed FA —~ — | ‘ Mee ‘a — j J | Fic. 3.—Evaporation rates in the beech-maple forest association at stations nos. 11, 12, and 13. canadensis, Adiantum pedatum, Asplenium angustifolium, Poly- stichum acrostichoides, Viola rostrata, Impatiens biflora, Erigenia bulbosa, and Epifagus virginiana. As this represents the climax formation for a large portion of the United States, it was regarded as a standard to which other plant associations could be referred, and accordingly 3 stations were established in it on May 30, and maintained until the end of October, giving a continuous record for 155 days. On account of the difficulty in reaching these stations, readings were made only every second week throughout 202 BOTANICAL GAZETTE [SEPTEMBER the season. Of the 3 stations in the beech-maple forest, no. 11 was in an area dominated by the sugar maple and well surrounded by maple seedlings. No. 11 was near a large beech tree on a slope covered with Asplenium angustifolium and Impatiens biflora, while no. 13 was in the midst of beech seedlings between two large trees of the same species. Together they seemed to represent the aver- age conditions in a beech-maple forest. The resulting graphs (fig. 3) are very similar, showing coincident maxima and minima differing but little in amount. The maxima are in July and August, and amount to little more than 12 cc. daily; the minimum occurs in September and is scarcely 3 cc. per day. The average rate of evaporation at the 3 stations for the 155 days is 8.1 cc. per day. It is here interesting to note the close correspondence between the records for this beech-maple forest and those obtained by TRANSEAU (8) in a mesophytic forest containing a small percentage of beech and situated on Long Island, N.Y., where for the period of observation from June 5 to July 2, 1907, the evaporation rate averaged 8.5 cm. daily, compared with 8.4 cm. daily during the month of June, 1910, in the Otis, Ind., forest. While it is not safe to draw any very definite conclusions from records covering but a single month, it may be assumed that the two associations differ very little in the amount of mesophytism developed. Several methods may be employed in comparing the data obtained from the various evaporation stations. Perhaps the best is to plot upon the same chart graphs representing the mean daily evaporation by weeks, from the several stations in the different associations (fig. 4). It will be seen that the graphs show several similarities, but more differences. The maxima and minima are generally coincident in time and proportionate in amount. All show great irregularity during spring and autumn, and a compara- tively high rate during July and August. The general height of the different graphs probably gives the most instructive and interesting differences in the various habitats. That of the cettonwood dune is farthest removed from those of the other asso- ciations, and shows a habitat not only with great evaporating power, but one of great extremes, the difference in rate between Ig1t] FULLER—EVAPORATION AND SUCCESSION 203 two consecutive weeks being nearly or quite to cc. per day during May and the first part of June, and on two occasions amounting to an increase of 100 per cent in one week as compared with the preceding. This occurring early during the growing period would doubtless be very unfavorable for the development of any seedlings, especially as it was followed by the very high rates of the succeed- MAY JUNE JULY: AUGUST SEPTEMBER] OCTOBER | i! 30 / 4 \ E | ae” 25 : \ N A Hi tl 4 Hitt / ALL aN Lith \ se | y \ / | i | iN age | it | \ a ! bre / \ Lh, | vel EL AA i ae ee /\\ ‘é lilt OA Pe i\i 4s i ‘ f A hn, 1 4 i Hj pra ‘ a ‘ x op i t i \ i i “L “ \ \ Py \, ‘ | x eS i \ iAd i f he x \ | ih / = 1 E iH E ‘a ; Ni Hi ‘ s / NT, RTM ast S ¢/ ‘ 4 Ar il ’ / 5 sy ve yf \ oe “a y Y Re ; Cottonwood dune ememmmmee y oe - ; tee oe 7 cena ene he - el Oak dune Beech-maple forest —...-.--.. =: Pd 2 te Fic. 4.—Mean daily evaporation rates in the sand dune plant associations and in the iene maple forest. 204: BOTANICAL GAZETTE [SEPTEMBER ing months. The high maximum occurring at midsummer would probably prove the excluding factor for all mesophytic plants, even if not combined with such other factors as the deficiency of soil water at the same time. Such a graph seems to depict rather well a habitat of atmospheric extremes making large demands upon all available water, and naturally and necessarily resulting in a xerophytic plant association, with a very limited undergrowth and an almost entire absence of herbaceous plants and seedlings. Perhaps nowhere could an association be found so entirely de- pendent upon vegetative reproduction for its maintenance, for almost without exception any increase in vegetation is the result of subterranean branches. The graph for the pine dunes is decidedly lower and more regular in its contour than that of the association which it succeeds. Its four nearly equal maxima would indicate that within its limits there was throughout the summer season a continuous stress rather than a series of violent extremes. On the whole, it shows a water- demand of little more than half of that occurring in the cottonwood dune. Its greatest divergence is plainly due to the evergreen character of its vegetation, and is seen in its low range in May and the first part of June, and again in October, when it falls below that of the oak dunes and is even less than that of the beech- maple forest. This would give good reasons for expecting to find within this association truly mesophytic plants, whose activities are limited to the early spring. The graph from the oak dune stations shows two surprisingly high points; one during May, that may be partially explained by the absence of foliage; and the other near the end of June, which seems to coincide with maxima in the other associations. On the whole, it is more moderate during the months of summer than that of the pine dune, but the difference is not so great as to make it surprising that its undergrowth differs but little from that found in the pine dune association. The graph from the beech-maple forest stations is one of mod- erate height and great regularity. It is but fair to say that weekly readings would probably have introduced some minor irregular- ities, but without changing its general course or influencing the 1g1t] FULLER—EVAPORATION AND SUCCESSION 205 average rate for the season. At no point does it reach to half the height of that from the cottonwood dune, but surpasses that of the pine dune in October. The data of these observations relate only to the stratum of vegetation immediately above the surface of the soil, and would be quite different at a height of one or two meters. This lower stratum, however, is the critical one for a forest association, for the development of tree seedlings occurs within its limits, and Cottonwood dune Pine dune Oak dune | Beech-maple fi t Fic. 5.—Diagram showing the comparative evaporation rates in different asso- ciations on the basis of the average daily amount from May 6 to October 31, 1910. Cottonwood dune Pine dune Oak dune Beech-maple f Fic. 6.—Diagram es the comparative ev spoention rates in different plant auiovintions on the basis 0 4 I day for any week between May 6 and October 31, 1910. therefore it is the portion of the habitat which determines the forest succession and hence the most important ecologically. A single example may be cited from the meager data obtained during the past season regarding the rates of evaporation in the more elevated strata. Very near station no. 13 in the beech-maple forest, an instrument was established 2.5 meters above the surface of the soil, and showed for the season an average of 12.7 cc. daily, as compared with 9.1 cc. daily for no. 13, whose atmometer was 20 cm. above the surface. 200 BOTANICAL GAZETTE [SEPTEMBER The comparative rates of evaporation in the different plant associations may be compared in other ways. If the average amount of water lost by the standard atmometer daily throughout the season be taken as a basis and represented in a diagram giving the loss in cubic centimeters (fig. 5), a graphic representation results which, however, tells little more than what has been shown differently in fig. 4. Likewise, the maximum daily rates for the week of greatest evaporation during the season gives a similar representation of the conditions in the several plant associations (fig. 6). Upon a percentage basis, with the average rate per day throughout the season in the beech-maple forest taken as a unit, the comparative evaporation rate in the oak dune is 127 per cent, in the pine dune 140 per cent, and in the cottonwood dune 260 per cent. As the months of July and August probably represent the critical portion of the growing season with reference to its water supplies, a comparison like the preceding might be made for those months only, when it would be found that the comparative evapo- ration in the oak dune would be 113 per cent, in the pine dune 146 per cent, and in the cottonwood dune 230 per cent. Summary 1. These data represent the evaporation rates in the lower but critical stratum of the plant associations. 2. Evaporation at different stations in the same plant associa- tion exhibits variations similar in character and degree. 3. The rate of evaporation in the cottonwood dune association, both by its great amount and by its excessive variations, seems a sufficient cause for the xerophytic character of the vegetation and for the absence of undergrowth. 4. Evaporation in the pine dune association exceeds that in the oak and beech associations except when the latter are devoid of foliage. 5. The vernal vegetation of the pine dune is quite as mesophytic as that of the succeeding association, thus agreeing with its lower evaporation rate during that portion of the year. 6. Evaporation in the various associations varies directly with the order of their occurrence in the succession. 1911] FULLER—EVAPORATION AND SUCCESSION 207 7. The differences in the rates of evaporation in the various plant associations studied are sufficient to indicate that the atmos- pheric conditions are efficient factors in causing succession. Conclusions From the study of the data available, it seems evident that the porous-cup atmometer measures with very considerable accuracy the atmospheric factors which combine in making demands upon the water-supply of the aerial portion of the plant; the data, there- fore, may be directly related to the plants in an association, and used in determining the comparative xerophytism of plant habitats in so far as they are determined by atmospheric conditions. In such determinations it would appear that the true measure of the limiting atmospheric factors must be found either in the demand throughout the entire growing season as expressed in the average evaporation rate for that period, or in a maximum demand of several days’ duration occurring at a period when the water-supply in the soil is deficient, such as would be expressed in a high rate continu- ing for a week or more in the latter part of the summer. In the associations studied, these demands show practically the same ratio when compared with one another (figs. 5 and 6). If this be the case, we have in the Livingston or Transeau atmometers instru- ments of sufficient precision to furnish the most valuable quantita- tive data in the study of plant associations. A complete study of the water relations of a habitat may be obtained by combining the data supplied by the atmometer with quantitative determinations of the available soil-moisture. It is hoped that some such data may be available in the near future. It seems highly desirable, in investigations of this character, that the different investigators employ instruments standardized to the common unit recommended by LivinesTon (5), and further that a plant association of wide distribution be used as a basis of comparison, and that the conditions in other associations be expressed in terms of these units whenever it is possible to do so. As no association is more widely spread in the United States than the climax mesophytic forest which is frequently characterized by the presence of either Acer saccharum or Fagus grandifolia, or 208 BOTANICAL GAZETTE [SEPTEMBER both, so no unit seems so well suited for this purpose as the beech- maple forest association or its ecological equivalent. Thus it may be said that the atmospheric conditions in the lower stratum of the cottonwood dune association during the growing season are 260 per cent as severe for plant life as those in the same stratum of the standard association (the beech-maple forest) during the same period. The writer hopes to continue and extend these investigations during the coming seasons. Grateful acknowledgment is made of the helpful advice and suggestions of Dr. Henry C. Cow Les, under whose direction this investigation has been conducted. THE UNIVERSITY OF CHICAGO LITERATURE CITED 1. Cow gs, H. C., The ecological relations of the vegetation of the sand dunes of Lake Michigan. Bor. Gaz. 2'7:95-117, 169-202, 281-308, 361-391. 1890. 2. Livincston, B. E., Evaporation and plant habitats. Plant World 11:1-10. 1908. ———, The relation of desert plants to soil-moisture and to evaporation. Parceple Institution of Washington, Publication no. 50. 1906. 4. TRANSEAU, E. N., A simple vaporimeter. Bort. Gaz. 49:459-460. 1910. 5. Lrvineston, B. E., Operation of the porous-cup atmometer. Plant World 6. Brown, Wm. H., Evaporation and plant habitats in Jamaica. Plant World 13:268-272. 1910 . Lrvincston, B. E., A aie cospeecting atmometer for ecological instrumenta- tion. Plant World 13:79-82. 1910. 8. TrANSEAU, E. N., The relation of plant societies to evaporation. Bor. AZ. 452217-231. I THE TETRANUCLEATE EMBRYO SAC OF CLINTONIA R. WILSON SMITH (WITH PLATE V) The following results are published in the belief that from the standpoint either of morphology or of phylogeny it is important we should become acquainted with the variations of the angio- sperm embryo sac. By searching out and comparing all deviations from the normal type, we may hope to ascertain the directions in which the embryo sac is varying at the present time, and perhaps we may also discover some clue to the path along which it has come. The results here given were obtained from a study of Clintonia borealis, collected in the neighborhood of Toronto and of Lake Joseph, Ontario. The youngest ovaries, collected May 9, showed the ovules already completely anatropous, each with a large archesporial cell, having its nucleus in the synapsis stage (fig. 1). The arche- sporial cell undergoes no cell division, neither cutting off a parietal cell nor dividing into megaspores, but, as in many liliaceous ovules, passes directely into the embryo sac. Its nucleus, however, suffers a twofold reducing division which is of considerable interest. The nucleus in the synapsis stage is very large; it is usually situated slightly below the middle of the cell, and occupies fully four-fifths of its width. In the condition represented in fig. 2, the protoplasm is becoming denser about the periphery of the nucleus in preparation for spindle formation, and the loops of chromatic material are beginning to separate and spread throughout the nuclear space. Subsequently, when the fibrils of the spindle are quite distinct, the chromatin is found segmented into chromosomes, which frequently appear in the x’s, y’s, and other forms, character- - istic of the heterotypic division. The number of these chromosome pairs I have not been able. to determine with certainty, since the nucleus is too large to be included. in one section. Further, since all my sections are cut 209] [Botanical Gazette, vol. 52 210 BOTANICAL GAZETTE [SEPTEMBER longitudinally to the ovule and therefore at right angles to the equatorial plate, it is difficult to make an accurate count of the chromosomes at a later stage of the mitosis. It is certain, however, that we are here dealing with the haploid number, probably 12. In vegetative divisions 20 or more chromosomes can easily be counted, though in this case also it is not easy to determine the number with certainty. The chromosomes when drawn into the equatorial plate are short and thick, almost globular, strongly contrasting in this respect with the long, crowded chromosomes of the vegetative division. In none of my material, though careful examination was made, could there be found any difference in the separating chromosomes (fig. 3). Those going to the lower pole are fully as large and give the same staining reaction as those going to the upper pole. But on arriving at the poles of the spindle, the two groups behave very differently. Those at the upper pole unite into a normal nucleus, while those reaching the lower pole fuse together into an irregular lump, without spongioplasm or distinct nuclear membrane. Fre- quently chromosomes or chromosome fragments fail to reach the principal mass, and remain scattered along the spindle or in the cytoplasm outside. When Flemming’s triple stain is used, these fragments, as well as the large chromatic lump, take only the safranin and appear semitransparent, while the chromatin of the upper nucleus, taking the gentian violet, appears dark and opaque. No wall is run in at the close of this division, but a distinct cell plate is formed by the thickening up of the spindle fibers (fig. 4). Division follows in each of the daughter nuclei resulting from the heterotypic mitosis. My material, however, does not furnish any examples of the prophase of this division, nor any information with respect to the chromosomes. The telophase is represented in figs. 5 and 6. In both figures the remains of the first spindle and its cell plate are still distinguishable (on the left side of fig. 6). A cell plate is formed also on the second spindles, but these and the earlier cell plate are transient structures and disappear shortly. The division of the upper nucleus results in this case also in the formation of an upper healthy nucleus and a lower irregular lump of chromatin. By the division of the lower of the daughter rgit] SMITH—CLINTONIA 211 nuclei two such lumps are formed. Thus the embryo sac now contains an upper healthy nucleus and three lumps of chromatic material without spongioplasm. The commonest arrangement is that of figs. 6 and 7 rather than fig. 5, the healthy nucleus being somewhat above the middle of the cell and much smaller than the nucleus of the mother cell. These successive divisions, especially the second, must be com- pleted very rapidly, if one may judge from the rarity of their occur- rence in the material. Thus, of about 350 ovules in the stages represented by figs. 2-7, more than 225 were in synapsis, and sie 5 in the second division. It can scarcely be doubted that the four nuclei just described are the four megaspore nuclei, and that megaspore formation in Clintonia differs from the normal type simply by omitting the formation of walls and by an earlier beginning of the degeneration of the sterile megaspores. It is clear that division of the imperfect nucleus. formed by the heterotypic mitosis can be of no importance in the subsequent history of the embryo sac; yet among 80 embryo sacs of the age of fig. 7, there was not one in which the lower nucleus had failed to divide. The three sterile nuclei could be found in every case. This fact would imply a strong hereditary tendency to a second division, such as we might expect to accompany megaspore forma- tion; and incidentally it would indicate that the impulse to nuclear division must originate in the cytoplasm, since so imperfect a nucleus cannot be regarded as capable of exercising any of the functions of a normal nucleus. A second peculiarity of the embryo sac of Clintonia is its uni- polarity. Only two divisions of the megaspore nucleus occur, and thus are produced four nuclei which, in their position, relation to one another, and later behavior, exhibit the characteristics of the four upper nuclei of a normal embryo sac. The change from megaspore to mature embryo sac, involving two nuclear divisions, requires an interval of about three weeks, and it is therefore difficult to obtain karyokinetic figures. That those I have been able to secure are in the late phases is probably due to slow infiltration of the fixing medium. 212 BOTANICAL GAZETTE [SEPTEMBER The fertile megaspore nucleus moves to a higher position and rests for some time: The spindle of the first division is parallel to the axis of the embryo sac, and the two nuclei formed are always one above the other, as in figs. 8 and 9. Again at this division a temporary cell plate is formed. The second division occurs simultaneously in the two nuclei, and the spindles are at right angles to each other. The two upper sister nuclei and the proto- plasm about them become the synergids; of the other two, one surrounded by vacuolated protoplasm and a plasma membrane becomes the egg, and the remaining one is a free nucleus, in position and appearance the upper polar. Usually at these stages some remains of the sterile nuclei are still recognizable, but it is not always possible to be sure all three are present. They stain much less deeply than when first formed, taking little safranin and appearing to have a dark color of their own, independent of the stain. They vary considerably in size, and very frequently appear pitted or vacuolated, as in fig. 9. They are usually situated in the lower end of the embryo sac, as in figs. 8 and 11; fig. 9 is an exceptional case, since one of the sterile nuclei appears in the micropylar region. _Up to the tetrad stage the protoplasm of the embryo sac shows no tendency to unipolarity; it is coarsely granular and evenly distributed. But after the first division of the megaspore nucleus, when there is considerable enlargement of the sac, the protoplasm of the antipodal region becomes scant and stringy with large irregular vacuoles; that of the micropylar region is much denser, and the numerous vacuoles, which appear only at a late period, are small and globular. A third peculiarity of Clintonia is its comparative sterility. Though it blossoms freely, only a very small proportion of the flowers result in fruit. Propagation by vegetative outgrowths of the rhizome is the common means of multiplication. An examina- tion of 50 ovaries, collected one week after the opening of the flowers, disclosed no embryos and no certain proof that fertilization had occurred. In several embryo sacs one of the synergids was partially disintegrated, and in two cases two free nuclei were found below the egg apparatus, presumably derived from division Igit] SMITH—CLINTONIA 213 of the polar nucleus. Whether or not fertilization occurs normally | in those ovaries which develop into fruit, I am at present unable to say, nor can I assign the cause of the large proportion of abortive flowers. Apparently it is not due to any imperfection in the microspore, which contains two normal nuclei and appears plump and healthy. An attempt to estimate the percentage of fertile flowers by field observation proved futile. An area producing 550 flowers was kept under observation and undisturbed, but all to no purpose. The flowers one and all were abortive, and two weeks after opening | had withered and fallen away, leaving only the shriveled pedicels. An attempt also was made to determine whether the sterility is due to imperfect pollination. A small number of flowers were artificially pollinated, but these like the others yielded no seeds. However, as several days of heavy rain interfered with the experi- ment, I cannot regard it as conclusive. Discussion The interpretation of the embryo sac of Clintonia is made easier by recent investigations of certain Onagraceae. GEERTS (6) finds that in Oenothera Lamarckiana the single archesporial cell gives rise to a tetrad row of megaspores, of which the uppermost develops, slowly absorbing the three lowermost and producing four nuclei arranged much as in Clintonia. The same condition is reported by MopILewskKI (10) as occurring in Epilobium angusti- folium, E. Dodonaei, Oenothera biennis, and Circaea lutetiana; in all these the unipolarity of the embryo sac is strongly marked and there is ‘‘double fertilization.’’ A comparison of the embryo sac development of these and of Clintonia makes it clear that the four nuclei of figs. 5-7 represent four megaspores. Further, in these six species the unusual condition prevails of having the upper megaspore fertile. The chief differences shown in the development of Clintonia are in the absence of walls separating the megaspores and in the large proportion of sterile ovules. A nearly similar embryo sac occurs in Oenone and Mourera, two genera of the Podostemaceae examined by WENT (14). A mother cell after synapsis divides into two; the upper of these 214 _ BOTANICAL GAZETTE [SEPTEMBER after division of its nucleus gradually disintegrates; the lower cell also gives rise to two nuclei, one of which, the lower, becomes a mere clump of chromatin, while the other divides twice and the four resulting nuclei arrange themselves as in Clintonia and the above named Onagraceae. Though WENT does not discuss the theoretical value of the first four nuclei derived from the mother cell, it seems clear they represent megaspores, of which that next the innermost is the fertile one. Thus two megaspores appear in the upper cell, and two in the lower cell which becomes the embryo sac. The development of one of the middle megaspores, although uncommon, is not unknown. It has been seen in Acacia and Eriobotrya (GUIGNARD 1881, 1882), Trapella (OLIVER 1888), some of the Araliaceae (DucAMP 1902), and Asclepias (FRYE 1902); to this list, which is taken from CouLTER and CHAMBER- LAIN’S Angiosperms, may be added Vaillantia and Collipeltis (LLoyD 1902). In the examples thus far reviewed, the four functional nuclei of the embryo sac are the direct derivatives of one of four megaspores. Some cases of a different nature remain for consideration. In Limnocharis (HALL 1902) tetrads are not formed; the first two nuclei of the mother cell place themselves at opposite poles, and while the upper gives rise to the egg apparatus and a polar nucleus, the lower remains undivided. Nearly similar is Helosis, but in this case the primary antipodal nucleus soon degenerates (CHODAT and BERNARD 1900; I have not been able to consult the original paper). Cypripedium (Pace 11) furnishes another example of a tetranucleate embryo sac. In this plant the mother cell divides once and the lower of the two daughter cells becomes the embryo sac, its nucleus undergoing two divisions. Miss Pace interprets the first two nuclei of the embryo sac as megaspore nuclei. Thus according’to this view the embryo sac of Cypripedium is compound, being the product of two megaspore nuclei. Miss PAce extended the conception of a compound embryo sac to Lilium, in which four megaspores are thought to function, and more recently CouLTER (4) has extended it to all those cases in which tetrad formation is apparently suppressed, and espe- cially to the 16-nucleate embryo sac of Peperomia and the like. 1gtt] SMITH—CLINTONIA 215 MCALLIsTER’S (7) discovery of temporary walls separating the first four nuclei of the embryo sac of Smilacina, which otherwise resem- bles Lilium, is strongly confirmatory of this interpretation. Though the results of the present paper have no direct bearing upon this question, it may be pointed out that in Clintonia and the Onagra- ceae we see for the first time a mature gametophyte of four nuclei proceeding from an indubitable megaspore; and the occurrence in the Penaeaceae (STEPHENS 12) and Euphorbia procera (Mopt- LEWSKI Q) of four symmetrically placed groups of nuclei, each group similar in appearance to the gametophyte of Clinionia, certainly suggests a similar origin for each group. No case is yet known of a 16-nucleate embryo sac derived from one of four megaspores. In Peperomia (BROWN 1) and the Penaeaceae (12) there are no tetrads, and reduction occurs in the embryo sac. In Euphorbia procera the history has not been traced back to the mother cell. In Gunnera' also (MopiLewskr 8, Ernst 5) there are no tetrads. The case of Pandanus (CAMPBELL 3) offers some difficulty; the embryo sac is said to be one of three sporogenous cells (presumably megaspores). But CampsBett did not obtain evidence where the reduction divisions occur, and the view that in the group of three “‘sporogenous cells” the upper two are parietal cells rather than megaspores is a fair inference from his figures and data. The point certainly needs further investigation. Clintonia, Eichhornia (SmMiItH 1898), Avena (CANNON 1900), and Asperula (LLoyD 1902) give us examples of four megaspores in one sac, and in Crucianella LLoyp (1902) found all four mega- spores germinating within the one wall. No one doubts that these are megaspores, simply because three of them or their products disintegrate. But surely the weightier evidence is that of chromo- some reduction, and this applies equally to Lilium, Peperomia, etc. This is the position taken by Coutter (4). He maintains that in the genesis of the angiosperm embryo sac ‘the essential part of the process is found in the first two divisions,” and he adds ““megaspores, at least their nuclei, cannot be omitted.” BRowNn (2) thinks we cannot make chromosome reduction the sole test of ‘ ERNST understands SCHNEGG (1902) to assert the occurrence of tetrads in Gunnera Hamiltoni, but the latter author does not figure tetrads nor use the word, and it seems probable his “ Viertheilung”’ refers to nuclear and not to cell division. % 216 _ BOTANICAL GAZETTE [SEPTEMBER megaspore formation, and he proposes a different criterion. ‘A distinction,” he says, “between the first division of a megaspore and a division giving rise to megaspores is that while in the first case no cell plate is formed on the spindle, in the latter case either a wall or a cell plate is formed on the spindle.”” Brown admits the compound nature of the embryo sac of Liliwm and Peperomia, but for the reason just quoted refuses to admit it in the case of Cypripedium. To be consistent, he ought not to allow it for Lilium, since in this case a cell plate is formed in the third mitosis of the embryo sac. His distinction breaks down, however, in the case of Clintonia; in fig. 8 the first division of the megaspore nucleus is accompanied by a cell plate. It seems to the writer that the general principle of a compound embryo sac, while not altogether free from difficulties, furnishes the explanation of a large number of abnormal embryo sacs. McMaster UNIVERSITY Toronto, CANADA LITERATURE CITED This list does not include papers catalogued in CouLTER and CHAMBER- LAIN’S Morphology of angiosperms (1903); such papers when referred to in the text are indicated by the author’s name and the year of publication in paren- theses, as (HALL 1902). 1. Brown, W. H., The nature of the embryo sac of Peperomia. Bor. Gaz. 46:445-460. 1908. 3 2 , The embryo sac of Habenaria. Bor. Gaz. 48: 241-250. a. ere D. H., The embryo sac of Pandanus, Bull. Torr. ne cha 36: 205-220. 1909. 4. Coutter, J. M., Relation of megaspores to embryo sacs in angiosperms. Bor. GAZ. 45:361-366. 1908. 5. Ernst, A., Zur Phylogenie des Embryosackes der Angiospermen. Ber. Deutsch. Bot. Gesells. 26a: 419-437. 1908 6. Geerts, J. M., Beitrige zur Kenntnis der Cytologie und der partiellen Sterilitat von Oenothera Lamarckiana. Rec. Tray. Bot. Néerl. §:93-206. 1909. 7- McALuisTer, F., The development of the embryo sac of Smilacina stel- lata. Bor, Gaz. 48:200-215. 1900. 8. MopiLewski, J., Zur Embryobildung von Gunnera chilensis. Ber. Deutsch. Bot. Gesells. 26a: 550-556. 1908 BOTANICAL GAZETTE, LIT PLATE V EN xy Be eeatbe, ae, By PAY SMITH on CLINTONIA tgtt] SMITH—CLINTONIA 217 9. MopILewskI, J., Zur wee Ws von Euphorbia procera. Ber. Deutsch. Bot. Gesells. 2721-26. terior seg von eae Onagraceen. Ber. Deutsch. Bot. Gosells. 2'7:287-292. 1900. 11. Pace, L., Fertilization in i porinadion Bor. Gaz. 44:353-374. 1908. 12. STEPHEN: Ne, ie Pe e embryo sac and embryo of certain Penaeaceae. Ann. Botany 23:363-378. 1909 13. —-——, Recent progress in the study of the embryo sac of the angiosperms. New Phytol. 8:377-387. 1909 . Went, F. A. F. C., The development of the ovule, embryo sac, and egg in the Podostemaceae.- Rec. Trav. Bot. Néerl. 5:1-16. 1908. 10. a! - EXPLANATION OF PLATE V All the figures were drawn with the aid of an Abbé camera lucida on a Leitz microscope. For fig. 1, ocular 1 and objective 7 were used; for all the others, a 2 mm., 1.30 aper. apochromatic immersion lens with compensa- tion ocular 4. The drawings have been reduced one-half in reproduction. Fic. 1.—Apex of nucellus with megaspore mother cell. Fic. 2.—Megaspore mother cell with nucleus emerging from synapsis. Fics. 3, 4.—First mitosis in megaspore mother cell. Fics. 5, 6.—Second mitosis in megaspore mother cell. Fic. 7.—Megaspore mother cell with four megaspore nuclei, one healthy and three degenerate. Fics. 8, 0. —Embryo sac showing first — of fertile megaspore nucleus. FIG. 10. — apex of an older embryo sac. Fic. 11.—Embryo sac of a fully opened wane in this, as in all the others, there are no eee THE EMBRYO SAC OF PHYSOSTEGIA' LESTER W. SHARP (WITH PLATES VI AND VII) The material of Physostegia virginiana (L.) Benth., upon which the present work is based, was collected near Alma, Michigan, in August 1909. Although the investigation has brought out no new point of fundamental importance, the results are deemed worthy of record. The ovule arises from the floor of the sporangial chamber as a small protuberance, which in growing pushes out the ovary wall in such a manner that it becomes completely surrounded by the latter except at the funiculus. At the time when the archesporium is distinguishable as a single hypodermal cell, the young ovule is slightly curved, and as growth proceeds this curving becomes more pronounced, until finally an anatropous condition is reached. A single massive integument is developed. The archesporial cell, which cuts off no parietals, grows rapidly, and is markedly elongated at the time when its nucleus goes into synapsis preceding the first division (fig. 1). This cell, which, on account of the occurrence of the heterotypic prophases in its nucleus, is to be regarded as the megaspore mother cell, by two successive divisions gives rise to a row of four megaspores (fig. 2). Of these the outer three degenerate (fig. 3), while the innermost enlarges and gives rise to the embryo sac. The nucleus of the functioning megaspore divides, and the two daughter nuclei take up positions near opposite ends of the sac, which becomes strongly curved, and, owing to rapid growth, develops a large central vacuole (fig. 4). Each nucleus divides, forming the four-nucleate stage (fig. 5). These four nuclei by one further division give rise to eight, and walls soon form, resulting in their organization into a typical egg apparatus, three antipodal * Contribution from the Botanical Laboratory of the Johns Hopkins University, No. 20. Botanical Gazette, vol. 52] [218 -roit] SHARP—PHYSOSTEGIA 219 cells ie soon multiply to several, and two free polar nuclei (fig. eee before the division to form eight nuclei, a laterally directed lobe begins to develop from the antipodal region of the sac, and at the eight-nucleate stage is very conspicuous (fig. 6). It rapidly invades the integumentary tissue, forming what may for convenience be called the ‘‘endosperm lobe,” since it is soon to contain nearly all of the endosperm formed. During these early stages it probably serves in a haustorial capacity, as does the greatly enlarged antipodal portion of the embryo sac of Saururus (JOHNSON 7). Meanwhile the micropylar polar nucleus migrates to the narrow portion of the sac near the antipodals, where it meets and fuses with the polar nucleus of the antipodal group. The resulting fusion nucleus is invariably found in this position (fig. 7). At about this time the antipodal cell which lies nearest the sac cavity takes on an appearance different from that of the others. It becomes binucleate, the cytoplasm changes in character, stain- ing more deeply, and rapid enlargement causes its wall to become strongly convex (fig. 7). This enlargement continues until the cell bulges out conspicuously into the embryo sac cavity (fig. 10), and its wall thus partitions off the small pocket in which it lies _ with the other antipodals. In stages somewhat later it bears much resemblance to the first few cells of the endosperm, but the possi- bility that it also is of endospermous origin is precluded by the ' fact that it has been observed side by side with an undoubted endosperm nucleus resulting from the triple fusion (fig. 9). The function of the cell in question is in all probability haus- torial, recalling the behavior of the basal antipodal in several genera of the Galieae (LLoyp 10), although in the sac under consideration the neighboring tissue is not actively invaded. It soon fills all the space formerly occupied by the other antipodals, which dis- organize and completely disappear (figs. 13, 14, 16), while in its general form and relation to the vascular supply it is especially well suited to the performance of a nutritive function during the rapid development of the endosperm. Later it disappears and the tissue of the region becomes irregularly broken down (figs. 18-20). 220 BOTANICAL GAZETTE [SEPTEMBER The great variety in form and behavior exhibited by antipodal cells, together with haustorial structures of many types, has been so well summarized (COULTER and CHAMBERLAIN 3) that further comment here is unnecessary, since Physostegia offers nothing essentially new. At the time of fertilization the general aspect of the embryo sac, together with its position in the ovule and its relation to the vascular supply, are as shown in fig. 8. The usual configuration of the egg apparatus is that figured here, but in other cases it exhibits considerable variation from this. In regard to the posi- tions of the nuclei and vacuoles, the synergids represented in fig. 7 show striking similarity to the egg, and it is conceivable that at least the larger one might function as such. The pollen tube, which has grown down the style into the _ sporangial chamber, makes its way around the stalk of the ovule, or at times directly over its summit, to the micropyle, through which it enters the embryo sac. Clear cases of fusion of the male nucleus with that of the egg were not observed, but the presence of the pollen tube within the sac, the disorganization of the syner- gids, the immediate elongation of the egg with divisions to form an embryo, and a triple fusion in the central region of the sac (fig. 9) make it reasonably safe to conclude that fertilization of the usual type occurs. The formation of the endosperm is of considerable interest. It is initiated by the division of the endosperm nucleus, which occurs in the narrow region of the sac near the haustorial antip- odal, as shown in fig. 10. The spindle has a transverse orienta- tion and is very broad, owing to the large number of chromosomes present. The division is accompanied by a longitudinal wall running through the middle of the sac, as shown in fig. 11, which represents a sac cut in a plane at right angles to that of fig. ro. Here the wall is still in process of formation, spindle fibers being evident at its extremities. Extension continues until it comes into contact with the sac wall at or near the end of the endosperm lobe (fig. 12), while in the micropylar lobe it was not observed to do so, and probably ends freely. The nuclei now lying in the two resulting parts of the embryo sac divide, forming transverse Tort] SHARP—PHYSOSTEGIA 227 walls (fig. 12), and further similar divisions give rise to a large- celled, thin-walled tissue which fills the endosperm lobe (fig. 13). This endosperm formation may cease abruptly at the narrow portion of the sac (fig. 14), but usually extends for a little distance into the micropylar lobe (fig. 16). The two-ranked arrangement so conspicuous in the endosperm lobe in fig. 13 and in the micropylar lobe in fig. 16 is doubtless due to the longitudinal separation of the embryo sac into two parts as described above. The cessation of endosperm formation at an iideinite point results in nuclei being left free in the cytoplasm of the micropylar portion of the sac (fig. 13). These nuclei, usually two in number, enlarge (fig. 14) and may occasionally divide, the walls which appear on the spindle fibers being evanescent. Often the nuclei were observed fusing. Consequently, from one to at least four may be present in stages somewhat later, but they play no further active part, and disorganize with the other contents of the micro- pylar lobe (figs. 18 and 19). In embryo sacs which show a wall at the first division of the endosperm nucleus it is usual for the sac to be thereby separated transversely into two chambers, and for endosperm to be formed only in the micropylar one. Among such cases the endosperm may pass through a free nuclear stage, as in Sagittaria (SCHAFFNER 12), Limnocharis (HALL 5), and Ruppia (MuRBECK 11); or walls may be formed at all of the divisions, as in Ceratophyllum (StrRas- BURGER 13) and the Nymphaeaceae (Cook 1 and 2). Less fre- quently both daughter nuclei resulting from the division of the endosperm nucleus take equal parts in the direct formation of cellular endosperm, as reported for Peperomia pellucida (JoHN- SON 8), Heckeria (JOHNSON g), and Datura laevis (GUIGNARD 4). From the above account it is seen that essentially this is the mode of endosperm formation in @/ysostegia, and in this sac the main point of interest lies in the fact that the first wall is longitudinal rather than transverse. The factors governing the orientation of the spindle and the consequent position of the wall are not at all clear, and the feature is probably best regarded as a minor peculiarity rather than a character of much significance. The restriction of endosperm to the antipodal portion of the 222 BOTANICAL GAZETTE [SEPTEMBER embryo sac has been observed in a number of cases (COULTER and CHAMBERLAIN 3), the condition reaching its extreme in Loranthus (HOFMEISTER 6 and TREUB 14), in which scarcely more than the lower one-tenth of the sac becomes filled with permanent endo- sperm tissue. Among the Labiatae the work of TULASNE (15), HoFrMEIsTER (6), and VESQUE (16) shows this to be the prevailing condition in several genera. In Stachys sylvatica TULASNE figures endosperm developing in the antipodal region of a slightly curved sac, but without the presence of a special chamber; and in Beton- ica a condition which may well represent a later stage in the same situation. The figures of HOFMEISTER indicate that in Lamium the endosperm lobe is well developed before fertilization, as in Physostegia. Although no antipodals and only two “Keim- blischen”’ are represented, HOFMEISTER has figured stages which correspond approximately to those shown in figs. 7, 8, 14, and 16 of this paper. In all of these cases the embryo is brought into contact with the endosperm by the great elongation of the micropylar cell of the proembryo. The earliest clearly observed stage in Physostegia is shown in fig. 13. Here the first division in the fertilized egg has occurred, and the micropylar cell by its great elongation is pushing the chalazal cell into the endosperm, the cells of which at this time are relatively few in number. Nearly all the elongation is accom- plished by the one cell, but this soon divides to several (figs. 14 and 16). The first division in the chalazal cell is longitudinal (fig. 15), as is also the second. Each of the four resulting cells is then divided into two by a transverse wall (fig. 16), and the subsequent divisions proceed with much regularity (figs. 17 and 18). At the time when the embryo becomes imbedded in the endo- sperm, the micropylar and endosperm lobes are approximately equal in size. The former, as has been noted above, disorganizes and in later stages becomes entirely obliterated, while the latter increases rapidly in size owing to the active growth of the endo- sperm. This growth is accomplished at the expense of the cells of the integument, which in the mature seed is recognizable as only one or two layers of cells (figs. 19 and 20). At the same time the Ig1t] : SHARP—PHYSOSTEGIA 223 embryo grows rapidly, becomes characteristically dicotyledonous, and displaces nearly all of the endosperm. It attains a length of nearly 2 mm. in the mature seed, the coat of which is formed from the ovary wall. Summary 1. The archesporium of Physostegia consists of a single hypo- dermal cell, which, without formation of parietals, functions ; as the megaspore mother cell. 2. The megaspore mother cell by two successive divisions gives rise to a row of four megaspores; the chalazal one enlarges and gives rise to the embryo sac, while the other three disorganize. 3. The mature embryo sac contains an egg, two synergids, three antipodal cells which multiply to several, and two polar nuclei which fuse. 4. During the formation of the embryo sac a lobe develops from near its chalazal end, so that the sac consists of two distinct parts joined by a narrower portion. 5. Double fertilization of the usual type in all probability occurs. 6. The endosperm is cellular from the beginning, the wall accompanying the first division of the endosperm nucleus being longitudinal through the sac. The chalazal portion of the sac, or ‘“‘endosperm lobe,’’ becomes completely filled with endosperm tissue, which invades and destroys nearly all of the integument; while the micropylar portion of the sac never contains more than a very few endosperm cells, and later disorganizes, becoming com- pletely obliterated by the encroaching endosperm. 7. The first division in the fertilized egg is transverse, and the chalazal cell, which becomes imbedded in the endosperm through the great elongation of the micropylar cell, develops very regu- larly into a typically dicotyledonous embryo, which displaces nearly all of the endosperm. This investigation was carried on under the direction of Pro- fessor D. S. JoHNson, to whom the writer is indebted for many helpful criticisms. w . ¥ ~JI om an BOTANICAL GAZETTE [SEPTEMBER LITERATURE CITED . Coox, M. T., Development of the embryo sac and embryo of Castalia odorata and Nymphaea advena. Bull. Torr. Bot. Club 29: 211-220. pis. 12, 13. 1902. . The embryology of some Cuban Nymphaeaceae. Bor. Gaz. a ae pls. 16-18. 1906. . Coutter, J. M., and CHAMBERLAIN, C. J., Morphology as angiosperms, 1903. Pp. 960-113, 177. GUIGNARD, L., La eae oo chez les Solanées. Jour. Botanique 16:145-167. figs. 45. Hatt, J. G., An a Ca study of Limnocharis emarginata. Bot. GAZ. 33:214-219. pl. 9. 1902. 6. HormeIsTerR, W., Neue Beitrage zur Kenntniss der Embryobildung der Phanerogamen. Abhandl. Kénigl. Sachs. Gesells. Wiss. 6: 533-672. pls. 1-27. 1850. . Jounson, D. S., On the ray of Saururus cernuus L. Bull. Torr. Bot. Club 27:365-372. pl. 1900, , On the enor ie embryo of Peperomia pellucida. Bor. GAZ. 30:1-11. pl. I , On the ecoact of certain Piperaceae. Bot. GAz. 34:321- 340. pls. 9, 10. 1902. Liovp, F. E., The comparative embryology of the Rubiaceae. Mem. Torr. Bot. Club 8:27-112. pls. 8-15. 1902. - MurBECK, S., Ueber die Embryologie von Ruppia rostellata Koch. KGnigl. Svensk. Vetensk. Akad. Handl. 36:1-21. pls. 1-3. 1 ScHAFFNER, J. H., Contribution to the life history of Sagittaria variabilis. Bot. GAZ. 23:252-273. pls. 20-26. 1897. . STRASBURGER, E., Ein Beitrag zur Kenntniss von Ceratophyllum sub- mersum und phylogenetische Erérterungen. Jahrb. Wiss. Bot. 3'7:477- 526. pls. Q-II. 1902. TrReEvB, M., Observations sur les Loranthacées. Ann. Sci. Nat. Bot. VI. 13:250-282. pls. 13-20. 1882. TuLaAsNE, L. R., Nouvelles aaa a oe es végétale. Ann. Sci. Nat. Bot. IV. 4: fous. pls. 7-18. . VESQUE, J., Développement du sac a yonnaie des phanérogames angiospermes. Ann. Sci. Nat. Bot. VI. 6:237-285. pls. 11-16. 1878. PLATE vr BOTANICAL GAZETTE, LI. SHARP on PHYSOSTEGIA BOTANICAL GAZETTE, LII \ x i war PLATE Vil i ad os 4 \ B Nagel NN aN ANSE Npessa \ i HAS. Y . SHARP on PHYSOSTEGIA 1git] SHARP—PHYSOSTEGIA d 225 EXPLANATION OF PLATES VI AND VII All figures were drawn with the aid of an Abbé camera lucida, have a cor- responding orientation, and show magnifications as follows: figs. 1, 11, 13-17, X 215; figs. 2-5, 9, X 462; figs. 6, 7, 10, 12, X 385; fig. 8, X81; figs. 18, 19, X45; fig. 20, X25. The following abbreviations are used: a, antipodals; e, egg; el, endosperm lobe; em, embryo; end, endosperm; f, fusion nucleus; h, haus- torial antipodal; 7, integument; m/l, micropylar lobe; , nucellus; 0, ovary wall; p, polar nucleus; pf, pollen tube; s, synergids; v, vascular supply. PLATE VI Fic. 1.—Young ovule with archesporial cell nucleus in synapsis. Fic. 2.—Four megaspores; the division to form the two micropylar ones is delayed. Fig. 3.—Four megaspores; the innermost one much enlarged, the other three disceusnizing. Fig. 4.—Two-nucleate embryo sac. Fic. 5.—Four-nucleate embryo sac. Fic. 6.—Eight-nucleate embryo sa G. 7.—Mature embryo sac; the — nuclei have fused and the antip- odals fae increased in number; one antipodal beginning to differentiate as a — cell. 8.—Ovule with mature embryo sa —Triple fusion of male and a nuclei; haustorial antipodal cell ees sites antipodals disorganizing. IG. 1o—First division of endosperm nucleus. IG. 11.—Daughter nuclei resulting from first division of endosperm nucleus; the wall accompanying the division is still in process of formation. IG. 12.—Subsequent endosperm divisions, all accompanied by walls. PLATE VII Fic. 13.—Two-celled proembryo coming into contact with the endosperm; false antipodal cell well developed; the other antipodals and the syner- gids have degenerated. Fic. 14.—Later stage; — formation has ceased eet at the narrow portion of the sac in this cas Fic. 15.—Chalazal cell of enh divided longitudinally. Fic. 16.—Somewhat later stage; the endosperm has extended into the micropylar lobe. IG, 17.—Later stage of embryo. Fic. 18.—Endosperm invading integument; embryo digesting endosperm; haustorial antipodal cell and micropylar lobe disorganized. Fic. 19.—Later stage. Fic. 20.—Section of nearly mature seed; the embryo has used up the greater part of the endosperm, which in turn has obliterated nearly all of the integument; seed coat formed from the ovary wall (0). Pa THE BRAZIL NUT* Wy. YOUNG (WITH PLATE VIII AND ONE FIGURE) The genus Bertholletia, to which is assigned the Brazil nut of commerce, was established in 1808 by HumBotpt and BONPLAND, who placed in it a single species, B. excelsa. A translation of BONPLAND’s description of the fruit of this species is as follows: Fruit a spherical, compound nut the size of a child’s head and often larger, divided internally into four cells, each of which encloses several nuts; covered on its exterior with a husk of a green color, smooth and shining. Main nut very solid, rough and marked by branching furrows on its outer surface, 6 lines (1 cm.) thick, divided internally into four cells by as many membranous dissepiments which become obliterated in part or entirely after the maturity of the fruit, but of which there always remain traces. The tree is described as 33 m. high, with a trunk 9 dm. in diameter. Leaves alternate, oblong, subcoriaceous, 1 dm. broad and 6 dm. sea borne on short petioles. Type locality, Rio Orinoco. On account of the great height of the trees, these botanists were unable to obtain the flowers, although it is said that they offered in vain an ounce of gold for specimens. On this account, they were uncertain as to the position which the genus Berthol- letia should occupy. More recent investigations have established it next to Lecythis among Lecythidaceae, an arrangement now universally accepted. It is worthy of note, also, that BONPLAND failed to describe either the operculum or the opercular opening of the fruit, although the latter is shown in his drawing as becom- ing decidedly narrower at the inner edge. For more than half a century after the publication of Bon- PLAND’S description of B. excelsa, the genus was accepted as mono- typic. Evidence was being gradually accumulated, however, which led to the recognition of a second species. Among the * Published by permission of the Secretary of Agriculture. 2 BONPLAND in HUMBOLDT and BonpLanp, Plantes equinoxiales 1: 110, 3 Spruce, RIcHARD, Notes of a botanist on the Amazon and Andes. Edited by A. R, WALLACE. Esa56. 5 Botanical Gazette, vol. on _ [226 1911] YOUNG—BRAZIL NUT 227 later botanists to contribute to this end may be mentioned BERG, who in monographing the Brazilian Lecythidaceae described under B. excelsa a species distinct from that of HumpBoipr and Bon- PLAND.* Although BERc’s description is marred by several errors, it is sufficiently accurate to demonstrate that the species described is not the B. excelsa of BONPLAND. BeErco’s drawing of the fruit or pyxidium is moreover quite different from that of BoNPLAND. It remained, however, for Mr. J. Mrers to point out clearly the distinction between the two plants and to describe BERG’s species under the name B. nobilis. The more noticeable points of distinction between B. excelsa and B. nobilis are collected from MreErs’s description in the follow- ing summary: B. excelsa Humb. and Bonp. Tree 1oo ft. or more high, with trunk 2.5-3 ft. in diameter. Leaves green; petioles 9-18 lines long. Floral panicle 8 in. long, with single branch ae! equal in length, and nodes + in. apart. Fruit slightly gee 0.16 in. in length Cortex of fruit smooth, palish, entire, persistent. Opercular opening with straight or concave walls, narrowing slightly at its inner edge. Operculum cylindrical, with round- ish, indented apex. Operculum breaks away and falls from the fruit as the columella shrivels. B. nobilis Miers. Tree somewhat taller than B. ex- celsa, with trunk 14 ft. in diameter. Leaves rufescent; petioles 3-6 lines long. Floral panicle 10 in. long, with about 5 short branches, and nodes ©.25-0.5 in. apart. Fruit approximately — spherical , usually under 5 in. in diameter. Cortex of fruit comparatively thick and rough, darker, cracking as the fruit dries and tending to loosen and drop off as the fruit is han Opercular opening with sharp edge and concave walls, and widening con- siderably inward. Operculum oval or radially com- pressed, conical and pointed at the apex. Operculum remains attached to remnant of columella an latter shrivels, falls into the cavity of the fruit. co i fo] 4 Berc in Martius’ Flora Braziliensis, I. 142478. 5 Miers, J.,On the Lecythidaceae, Bertholletia. Trans. Linn. Soc. II. 30: 195-199. 228 3 BOTANICAL GAZETTE [SEPTEMBER The differences noted above, as far as they relate to the fruit, are well shown in the copy of Miers’s drawing, reproduced half- size in text fig. 1. The idea that B. excelsa Humb. and Bonp. is the source of commercial Brazil nuts has become so thoroughly grounded in popular and even in botanical literature that it seems to be accepted on faith and passes unchallenged. The extent of this belief will be apparent when we consider that of the following quotations only the last two, or possibly three, make any mention of a second species, to which, moreover, they assign a wholly subordinate position. Brazil nut.—One of the triangular edible seeds of a tall South American tre (Bertholletia excelsa).—Standard Twentieth Century Dictiona Brazil nut-—The seed of the fruit of Bertholletia excelsa.—Century Dic- tionary. Brazil nui.—An oily 3-angled nut, the seed of the lecythidaceous Brazilian tree Bertholletia excelsa.—Webster’s New International Dictionary. Cream nut (Bertholletia excelsa Humb. and Bonp.).—This is a common nut in our markets brought from Brazil; hence it is often called Brazil nut.—Nut culture in the U.S., p. 106, Div. of Pomology, U.S. Dept. Agriculture Brazil nuts, cream nuts, Para nuts.—These are edible nuts imported from Brazil. The nuts are the product of Bertholletia excelsa (Humboldt and Bon- pland).—U.S. Disp., roth ed., p. 1420. Bertholletia excelsa.—Brazil nut.—A large tree belonging to the family Lecythidaceae, and yielding the Brazil or Para nuts of commerce. A tree 100 to 150 ft. high, ie throughout northeastern South America to the Island of Trinidad—Coox and Cotiins, Economic plants of Porto Rico, Contrib. U.S. Nat. Herb. é 291. 1903 Beriholletia Humb. and Bonp. —Tall trees. One or two species. South erica. a. B. excelsa Humb. and Bonp.—Seeds, Brazil nuts, Para nuts, cream nuts, nigger toes, Castana nuts.—Lyons, A. B., Pl. names, sci. and pop., 2d ed., p. 71. Bertholletia.—Brazil nut, Para nut, cream nut, nigger toe.—Species 2, both of which furnish Brazil nuts——Hastines, G. T., in Bartey’s Cycl. of Hort. The Brazil nut, also called Para nut, from the port of shipment, is the seed of a large tree (Bertholletia excelsa Humb. and Bpl.).—Another species, B. nobilis Miers, also yields a similar nut.—WrnTon, A. L., Microscopy of vege- table foods, p. 312. This state of affairs seems to be due primarily to BONPLAND’S assumption, stated in connection with his description of B. excelsa, 1g1t] YOUNG—BRAZIL NUT 220 that it is this species which furnishes the Brazil nut. The long time which elapsed previous to the identification of a second species allowed this view to become so thoroughly established that MieRs’s work appears to have been overlooked by persons inter- Fic. 1.—Reproduction of Mrers’s drawings of Bertholletia, copied half-size from Trans. Linn’ Soc. 30: pl. 37. figs. 1-3, Bertholletia excelsa: 1, pyxidium cut open to s! structure; 2, section of opercular opening; 3, operculum; 4-7, Bertholletia i 4, pyxidium cut open to show structure; 5, section of opercular opening; oper- culum; 7, a — of seeds (Brazil nuts).—Published by courtesy of the fein Society of Lon 230 BOTANICAL GAZETTE [SEPTEMBER ested in botany from the economic standpoint. The work of various botanists during this interval, and especially BrRe’s description of B. nobilis under the name B. excelsa, no doubt con- tributed to the same end. Moreover, the seeds of the two species, so far as can be judged from the descriptions and drawings avail- able, are so similar as to be distinguished with difficulty if at all. After making a careful study of the situation, the writer has become convinced that the commonly accepted view is erroneous, and that the Brazil nuts of commerce are derived from B. nobilis Miers (B. excelsa Berg) and not from B. excelsa Humb. and Bonp. - The reasons for this view are given below. t. Commercial samples of Brazil nuts contain, in larger or smaller numbers, opercula derived from the fruit, and the presence of these in itself is evidence that the nuts were derived from B. nobilis, since, as has been noted in the comparison, the opercula fall from the mature pyxidia of B. excelsa, and hence would not find their way into samples of nuts from that source. On the _ other hand, their presence among nuts from B. nobilis is perfectly normal and what would be expected, since in this species the opercula fall into the interior of the pyxidia and become mixed with the nuts. . Moreover, the opercula, so far as the writer has been able to observe, are always of the B. nobilis type, as shown in fig. r. They vary in form from ovoidal bodies to cones of varying slope, being modified apparently by the size and degree of persistence of the columella, as well as by the extent of the grinding against surrounding nuts to which they have been sub- jected during shipment. All, however, are provided with a dis- tinct apical point except where it has been broken off, in which case the fact is usually quite evident. It cannot be denied that the absence of opercula of the B. excelsa type does not preclude the possibility that nuts of this species may be occasionally mixed with those of B. nobilis, since the writer is not aware that it is possible to distinguish the species from the character of the nuts alone. : . 2. Every pyxidium of the Brazil nut which the writer has had an opportunity to examine has indicated that the fruit is that of B. nobilis. Their main points of structure are well shown in YOUNG on BRAZIL NUT 1911] YOUNG—BRAZIL NUT 231 figs. 2 and 3, which illustrate pyxidia obtained from different sources. A comparison of the photograph with Mrers’s descrip- tion of B. nobilis will leave no doubt of their identity. Most if not all of the pyxidia which the writer has examined were brought to this country by the importers of Brazil nuts, and represent the source of the nuts in which they deal. 3. The testimony of others, although comparatively scanty, should not be overlooked, since it is improbable that the authorities quoted as stating that the Brazil nut is the seed of B. excelsa have given the matter any exhaustive study. After this description of B. nobilis, Miers states ‘‘these seeds are known in commerce as Brazil nuts,’ and proceeds to give statistics regarding their exportation and use. Moreover, BERG’s error regarding B. excelsa, although perhaps adding to the confusion, is in reality indirect evidence of the same fact, since it is doubtful whether he would have confused the two species had he not been sure that the speci- mens from which he made his description were those of the Brazil nut, which he, in common with others of his time, regarded as B. excelsa. Norte.—Acknowledgment is due Mr. H. C. SKEELS of the Office of Foreign Seed and Plant Introduction, U.S. Dept. of Agriculture, who has reviewed the work and confirmed the conclusions of the writer. U.S. Derr. or AGRICULTURE WasaincTon, D.C. EXPLANATION OF PLATE VIII Bertholletia nobilis Miers.—The form of the operculum and opercular opening, and the loose, broken cortex are characteristic of this species. Fic. 1.—Opercula from So Brazil nuts; x. Fic. 2.—Entire pyxidia; Fic. 3.—Pyxidium cut open me show structure; nuts in piace; small speci- men; natural size. Bearer eR ARTICLES AN IMBEDDING MEDIUM FOR BRITTLE OR WOODY TISSUES A mixture of rubber and paraffin as an imbedding medium for brittle objects was first described by J. B. Jounston,’ and the following is a modification of his original formula. -Melt 98 grams of paraffin of the melting point usually used, to it add 0.4 gram of asphalt (mineral rubber) and heat until the asphalt is dissolved, giving the paraffin a dark color. The purpose of the asphalt is to increase the power of the paraffin to dissolve rubber. For very woody tissue so much asphalt may be added that the paraffin becomes black. To the dark-colored liquid paraffin add 2 grams of crude rubber cut into very small pieces, and keep the mixture at a temperature of 95° C. for several hours, or at the melting point of the paraffin for several days until the solution is saturated with rubber. Then decant the clear supernatant liquid and allow it to cool. Use the dark solid exactly as paraffin is used. There are two points which require care in manipulation. First, as the rubber tends to separate out slowly if the mixture remains in the melted condition too long, allow the mixture to cool when not infiltrating; second, the elasticity of the mixture leads to the formation of internal air bubbles if the “blocks” containing the imbedded object are cooled too rapidly. During winter, when the water is very cold, it is best not to immerse the blocks completely, but simply let them rest on the surface until hard. The addition of the rubber decreases the melting point of the mixture by two or three degrees. The relative amounts of the different components of the mixture can be modified to suit individual requirements, and with a little practice the results obtained equal those obtained with the much more cumber- some celloidin method.—H. M. Benepict, University of Cincinnati. t Journ. Micr. and Lab. Methods 6: 2662. 1903. Botanical Gazette, vol. 52] [232 CURRENT LITERATURE BOOK REVIEWS Plant and animal breeding for secondary schools There has been a growing demand in recent years that the secondary schools, especially those located in rural districts, shall give courses in agri- culture, domestic economy, and other subjects bearing a practical relation to the life of the people in whose midst the schools are located. In several states these subjects are now a part of the prescribed course. Such require- ments make demands for properly trained teachers and for suitable text- books. A well-conceived and charmingly written manual of plant and animal breeding has been prepared by Professor EUGENE DavENporRT' to partially meet this growing need. In some respects this work is essentially an abridgment of the same author’s earlier work on Principles of breeding, but less attention is given to philo- sophical discussions and more to facts regarding the origin and history of the various domesticated races. Several early chapters describe the manner in which plants and animals came to be domesticated, and point out the need of their further improvement. A chapter on the “ways of the wild” gives a very readable discussion of natural selection and the survival of the fittest, thus giving a basis for a proper appreciation of the relation between artificial selection and the natural evolutionary processes. The principles which are involved in the improvement of plants and animals are then discussed at some length, chief attention being given to Gatton’s Law of ancestral heredity and the correlation table. MENDEL’s laws are given very inadequate treatment. The author evi- dently has hazy conceptions of unit characters, dominance and recessiveness, latency, atavism, mutation, etc., and his discussions involving these subjects lack the definiteness and accuracy which characterize the rest of the book. He repeatedly emphasizes the statement that each individual possesses all the characteristics of all its ancestors, a statement directly opposed to all Mendelian experience. This lack of precision in the treatment of the prin- ciples of Mendelian heredity constitutes the most fundamental defect of the ook. It is not only too plainly apparent in the discussions, but is also seen in a number of erroneous definitions in the glossary, as the following examples a show: ‘“Gamete, the fertilized ovum”; “Mutant, an individual or ‘Daveieek yaa Ne Dome sticated animals and plants. A brief treatise upon the origin and evelopment of domesticated races, with special reference to the methods of improvement. pp. xiv+ 321. figs. gg and frontispiece. Boston: Ginn & Co. 1910. 233 234 BOTANICAL GAZETTE [SEPTEMBER strain essentially new and produced spontaneously by nature through aia bud variation, or otherwise, synonymous with the older term ‘sport’’’; “Zyg tions as these. However, the defect in regard to Mendelian heredity is mainly a “sin of omission,’ and the prepared teacher can easily fill in the vacancy, especially with the aid of PUNNET?T’s Mendelism. DAVENPORT’s book can not fail to interest, instruct, and inspire, and is deserving of a wide distri- bution.—Geo. H. SHULL. Popular manuals The scientific men and women of England have always been interested in interpreting the result of science to the intelligent public not trained in science. Even their scientific papers are apt to be more popular in form than are those prepared in the United States. We cannot but feel that science in America has suffered very much from lack’of proper interpretation. Those who are willing to write on scientific subjects for popular reading are usually unfit for the task; and those who are fit, are unwilling. The projected Cam- bridge Manuals of Science and Literature furnish a notable illustration of the continuous effort in England to interest the public in scientific matters. They are not intended primarily “for school use or for young beginners,” but also for educated readers who want brief and simple, and at the same time authori- tative statements of recent discoveries. The five volumes now issued, dealing with cree will indicate the subjects treated and the kind of authors pre- paring them The coming of evolution, the story of a great revolution in science, by Joun W. Jupp (171 pp.); Heredity, in the light of recent research, by L. DONCASTER (140 pp.); Plant-animals, a study in symbiosis, by FREDERICK KEEBLE (163 pp.); The natural history of coal, by E. A. NEWELL ARBER (163 pp.); Plant life on land, considered in some of its biological aspects, by F. C. Bower (172 pp.). : To issue such a series, at one shilling a volume, is to place this material in the hands of a very wide range of readers, and must react favorably upon the general interest in science. Another series, having the same purpose, is called Home University Library, ten volumes of which have now appeared. It is an English series (Williams and Norgate), as one might expect, published in this country by Henry Holt and Company. The books are larger than the Cambridge Manuals (uni- formly 256 pp.), selling for 75 cents, and are more pretentious in contents, suited doubtless to a somewhat better trained group of readers. Four of the volumes are of interest to botanists, as follows: Modern geography, by Marion I. Newsictn; Polar exploration, by W. S. Bruce; The evolution of plants, by D. H. Scort; Evolution, by Patrick GreppEs and J. ARTHUR THOMSON. tgit] CURRENT LITERATURE 235 A third series is the A ppleton’s Scientific Primers, edited by J. REYNoLDS GREEN, an English botanist. Three of this series have appeared, the third by the editor and entitled Botany. It is written from the English point of view, which lays much stress on details and terminology, but is effective in ieedentiag the plant as a living organism, for the author is a physiologist. A great deal of material is packed in the 128 pages, and it would be interesting to know the impression such material makes upon those without laboratory experience.—J. M. C Mendelism PuNNET?’s little book? on Mendelism, which was one of the first attempts at a simple popular presentation of its subject, has been completely rewritten and enlarged for its third edition. It is in fact a new book, written however from the same point of view and for the same circle of readers. The author limits himself to the presentation of illustrative examples, with no attempt at exhaustiveness in any phase of the subject, referring readers to BATESON’S book on Mendel’s principles of heredity for more detailed information and for references to the literature. The material used to illustrate the various principles is well chosen, and is mostly derived, as might be expected, from the work of the Cambridge group of geneticists, of which the author is one. This results in a decided advantage, since the author’s familiarity with his material favors clarity and vividness of presentation. The slight sense of provincialism given by this method is in this way more than compensated for. While the treatment is in the main admirable, several unfortunate errors have crept in. It is stated (p. 2) that “among animals the female contributes the ovum and the male the spermatozoon; among plants the corresponding cells are the ovules and pollen grains.” . Several other zoological writers on genetic subjects have obviously made the same mistake. The animal ovum (after maturation) and spermatozoon are homologous cells, but ovules and pollen grains are not single cells, and not even homologous structures, the ovule consisting mostly of maternal somatic tissue, and the pollen grain being a much reduced gametophyte. The embryo sac within the ovule, and the sperm nuclei in the pollen tube, approximately correspond to the ovum and spermatozoa. On page 51, line 16, c should be C, and in fig. 8 on the following page the three squares which are black should be albino, and the three mark “albino,” but containing C, should be black. The author assumes that dominance of a character always indicates that such character is due to some- thing added to the recessive form, thus ignoring the possibility pointed out several years ago by the reviewer that the positive character may be reces- *Punnetr, R, C., Mendelism. Third edition, entirely rewritten and much_ enlarged. at mee 192. pls. 6 and frontispiece. figs. 32. New York: The Mac- millan Co. 3The “presence and absence” hypothesis. Amer. Nat. 43:410-419. 1909. 236 BOTANICAL GAZETTE [SEPTEMBER sive through the failure of the unpaired gene in the heterozygotes to produce a visible effect. A number of excellent text figures and six plates, five of them colored, add greatly to the attractiveness of the book, and the press work leaves nothing to be desired. This little manual is worthy of an even larger measure of the appreciation which has been given to its two preceding editions by those engaged in other scientific fields, and by general readers who are not themselves engaged in science, but who like to keep themselves informed on the advances that are being made in science.—GrEo. H. SHULL. ° MINOR NOTICES Alpine plant life.—In an attractive volume intended for the general reader, ARBER‘ has described the plant life of the higher altitudes of the Swiss Alps. The plants are treated in ecological groups, and an evident effort has been made, not unsuccessfully, to maintain the ecological point of view through- out. It might be questioned if most modern ecologists would find as many beautiful adaptations as are evident to the author, who declares that not only the color of the flowers, but the density of their pigment ‘“‘may be primarily due to a specialization in favor of a particular class of insect visitor.” Other adaptations of alpine plants receive considerable attention, and the probable origin of the alpine flora is briefly discussed. The text is pleasing in style, the descriptions are accurate and profusely illustrated by more than 75 excellent plates and figures. A glossary of botani- cal terms and a chapter on the structure of the flower should make all the descriptions intelligible even to the reader who is entirely without scientific training.—Gero. D. FULLER. NOTES FOR STUDENTS Cecidology.—The anatomy and histology of insect galls continues to be an interesting and profitable field not only for the entomologist, but also for the plant pathologist and the experimental biologist. _WEIDEL’ gives us a valuable study of the life history of the gall of NV euroterus vesicator Schlecht. — the gall characters which are recognized by the zoologist to a owth enzyme,” he discusses his methods. These methods are well worthy 4 ARBE . A. NEWELL, Plant life in alpine Switzerland. 8vo. pp. xxiv+355- pls. 47. pans gp London: John Murray. toto. $1.50. 5 WEIDEL, F., Beitrige zur Entwicklungsgeschichte und vergleichenden Anatomie der Cynpidengallen der Eiche. Flora 102:279-334. pl. 15. figs. 49. I9gtt. ro1t] CURRENT LITERATURE 237 of notice by our American workers. The mature galls were taken into the the plant tissue. The “growth enzyme”’ is from the larva, and e gall kes ac galls. He also states that the character aig ee somewhat upon the part of the host plant on which the gall is form KUsTER® gives a brief discussion and ee of one of TROTTER’S’ recent papers, in which he compares the protoplasmic and histological characters er He calls attention to the necessity of comparative study of the structure of gall with the normal structure of the plant. The galls and dicot stems both have the radial arrangement of parts, with parenchyma tissue in the center, but the fibrovascular bundles of the galls are not so well developed as in the stems. KUsTer sees enough differences in structural characters to prevent agreement with TROTTER, but does not go into an extended discussion of these differences. REVILLIUS® gives a very ranach discussion of certain pseudo-galls or ead tedinate The first of these was briefly described by Rus- SAAMEN IQOI. e author agrees with RUBSAAMEN, but gives a more detailed PRE The insect attacks the upper surface of the leaf, causing the tips to curl. The upper epidermis is seriously injured and the mesophyll somewhat distorted, but the palisade cells only slightly changed. The meso- phyll is poorer in chlorophyll than in the normal leaves. When the buds are attacked they fail to develop. A similar gall not previously described occurs on S. graminea. A Thysanopterocecidia on the Polygonum Convolvulus is also described, but in this the insect attacks the under surface of the leaves. The structural characters are practically the same as the preceeding. The LEEUWEN-REIJNVAANS® give a fourth paper on the cecidia of Java, ‘Kis STER, geen be die. Sprossihnlichkeit der protoplasmatischen Gallen. Marcellia 9:159, 7 TROTTER, “ es a di una omolgia caulinare nelle galle prosplastiche. Marcellia 9: 109. 1911. § GREVILLIUS, Dr. A. Y. von, Notizen ueber Thysonopterocecidien auf Stellaria media Cyr., S. graminea L., und Polygonum Convoloulus L. Marcellia 9: 161-167. 1gto ice UWEN-REIJNVAAN, J. eae W. Doctors, Einige Gallen aus Java. Vierter Beitrag. Marcellia 9: 168-193. 238 BOTANICAL GAZETTE [SEPTEMBER in which they describe 50 specimens, most of which are caused by insects of the genus Cecidomyia. This material was collected in the Oengaran moun- tains at an elevation of 700 to 1000 meters. Large, soft galls with water parenchyma were especially abundant. TROTTER™ gives brief descriptions of 24 species of galls collected by Dr. Forti in Asia Minor, and occurring on Quercus aegilops L. (Q. vallonea Kosch.), Q. lusitanica Lan., and Rosa sp. Most of these species had already been described. KIeFrrerR (Bitsch) and Hersst (Valparaiso)™ describe seven new species of cecidia and insects producing them, from Chile, and give brief descriptions of those species not previously described. Among the papers on American cecidology we note FELT’s” key, parts of which will be serviceable to the botanist as well as to the entomologist, but there are not enough characters of the galls given to enable exact determi- nations. 1TH _M. PATCH’ gives a most excellent piece of work on the aphis galls of the elms. Although, with the exception of brief descriptions of the galls, the major part of the work is devoted to the biology and life history of the insects, the work is of great value to the botanist. Several species which have previously been very much confused are separated in a manner which makes them easily omanreng The value of the work is increased by the illus- trations and bibliographies SmitH’s™ bulletin comes to us as a valuable contribution on bacterio- cecidia. The historical discussion and the long series of experiments are interesting and valuable. It is very doubtful if any cecidia have a wider range of host plants than has been proven for this one. The fact that the galls are produced most readily in soft, rapidly growing tissues, is in harmony with results already obtained by the study of insect cecidia, and further studies will doubtless bring out other similarities. The very limited dis- cussion given to the stimulus and to the character of the cecidia leads us to hope for another bulletin in which these phases of the subject will receive more attention. Norton’ records a very interesting crown swelling of the peach due to to TROTTER, * oo di Galle Roccolte dal Dr. A. Fortr in Asia Minor. Mar- sm - a und Hersst, P., heigl sa und Gallenthiere aus Chile. ak f Bak, Wats u. Infek. 29: 606- » Pett, BP. ae midges of Aster, ey one and Salix. Jour. Econom. Ent. ba sara = gat ‘ , Gall aphids of the elm. Bull. No. 181, Maine Agric. Experi- ment Nealon IgII 4 Smita, E. F,, Brown, N. A., and Townsenp, C. O., Crown gall of plants; its cause and remedy. Bur. Plant Industry, Bulletin 213. rg1t. *s Norton, J. B. S., Crown swelling disease of peach. Phytopathology 1:53, 54- 1911. tort] CURRENT LITERATURE 239 unknown causes. The structure of the swelling is characterized by spongy masses of parenchyma filled with starch and interspersed with woody layers. An interesting myco-cecidia of the orange is described by FLORENCE Hepces. This cecidia is attributed to Sphaeropsis tumefaciens, nov. sp., which is described. The external characters of the gall are given, but the development and histology are omitted—MeEt T.- Cook. Phycomycetes.—PETERSEN gives an abbreviated English translation of his paper on the aquatic Phycomycetes of Denmark, which was originally published in Danish. The paper” is divided into three parts, the first dealing with the phylogeny and relationships of the Phycomycetes, the second with their occurrence and distribution, and the third with descriptive taxonomy. s to their phylogeny, the author adheres to the view that the aquatic Phycomycetes and their near relatives constitute a phylogenetic series. If they were derived from the algae at various levels, they would hardly show the homogeneity which runs through the aquatic forms. As to the direction of their evolution, he holds that the lower Phycomycetes have been derived from the higher forms through reduction of the plant body. This view, which necessitates the assumption that motile zoospores and cilia were acquired by the degenerating forms, meets with difficulty when the non-aquatic Pero- nosporales are considered. The author regards the Pythiaceae, on account of their probable relationship with Lagenidium, as the ancestors of Lagent ceae. The Peronosporales, to which the Pythiaceae belong, would pultoadl form a part of the reduction chain, and it would be necessary to assume that zoospores adapted to aquatic conditions have arisen among the aerial Pero- nosporaceae from conidia eminently suited for aerial] distribution. The alternate ypothesis that the Peronosporaceae are losing their aquatic characters in a dry habitat, instead of acquiring them, seems more reasonable. e chief argument of the author is directed against the view of FIscHER that the Phycomycetes are derived from the Monadineae. Here he rightly points.out, among other differences, that the germinating zoospore of the Phycomycetes leaves the spore membrane behind, while in the endophytic Monadineae the zoospore makes its way in its entirety into the host cell. The author rightly regards the Synchytriaceae as a distinct group, which represents a line of development different from the rest of the Chytridiales. The idea is not fully carried out, however, in his synopsis of the families given later. In the second part of the paper are given many interesting observations on the biology and distribution of the aquatic Phycomycetes in Denmark. The Saprolegniales occur frequently on fish and frog spawn, but they do not © HEDGES, FLORENCE, Sphaeropsis — noy. sp., the cause of the lime and orange knot. Phytopathology 1:63-6s. 7 PETERSEN, H. E., An account of chk a Phycomycetes, with bio- logical and ——— remarks. Ann. Myc. 8:404~560. figs. 27. 1910 over Ferskvands-Phycomyceten. Botanisk Tideskrift 29: t). jer 345-429. he. = 1g0og (with English abstract 240 ~ BOTANICAL GAZETTE [SEPTEMBER produce such epidemics among fish as have been reported in other countries. Dead twigs, which have fallen into the water near the shore, form the most common habitat for these fungi. They sometimes occur on remains of aquatic plants, like Nuphar and Nymphaea, but herbaceous plants do not generally seem to be a favorable substratum for their growth. Leaves which fall into ngi. ) Phycomycetes is in early spring, while the water is still too cold to allow growth of bacteria and infusoria. The rest of the paper consists of a taxonomic arrangement of the species, with notes as to their habits and occurrence. The brief descriptions which are given for the known species in the former paper are omitted in the trans- lation, diagnoses being given only for the new species. Of these there are twelve. One, Pythiomorpha gonapodyoides, represents a new generic type. It is unfortunate that the designation ‘“‘sp. nov.”” accompanies the names of these species in the translation. It is needless to point out the confusion that may result from such double publication of new species in editions appearing nearly a year apart. The paper, which is an excellent achievement in local botany, shows the results which sustained study of a group may be expected to yield in territory of which the flora is presumably fairly well known. It is to be hoped that it may direct the work of botanists of other countries to this fruitful field. According to a brief article by MatrE and Tison,™ sexuality usually attrib- uted to Urophlyctis is lacking in that genus. In Urophlyctis empty cells are found accompanying the sporocysts, thus making it appear as if conjugation had taken place. These empty cells, however, according to the authors, are nothing more than the older vegetative cells whose contents have passed into the younger cells, which arise as buds from the older ones. The authors con- genera, Urophlyctis, Physoderma, and Cladochyirium, forming a well-defined natural grow CHMER RED has described the abnormalities occurring in a species of of these plants and some of which have been figured by several investigators, occur mostly in the sporangia, and cause these organs to assume forms and modes of behavior characteristic of other genera of the Saprolegniales. Varia- tions are described simulating the sporangia of Leptomitus, Pythiopsis, Achlya, %8 Marre, REeNf, et T1soNn, ApRIEN, Recherches sur quelques Cladochytriaceae. Compt. Rend. 152: ie 10%. nee 19 LECHMERE, A. FE, g ofa species of Saprolegnia New Phytologist 9: 305-319. pls. 1, 2. Ig10. Tori] f CURRENT LITERATURE 241 Dichtyuchus, and Aplanes in form, manner of discharge, and germination of spores. A common type of variation is one in which chains of rounded spo- rangia discharging laterally are formed. It is well to have these variations recorded from observations on a single form in pure cultures—H. Hasset- BRING : Photosynthesis in water plants.—BLAcKMAN and SmirH” have published two papers upon “‘Gaseous exchanges of submerged plants,” being nos. 8 and 9 of the excellent series on ‘‘Experimental researches on vegetable assimilation and respiration”’ issued from BLACKMAN’Ss laboratory. The first of the present papers deals with ‘‘A new method for estimating the gaseous exchange in submerged plants.’”’ Instead of using the oxygen elimination as the basis for study, the CO, consumed is determined. Water of known CO, content (determined by tritation) is passed over submerged plants of a given illumi- nated surface, and the CO, withdrawn for photosynthesis determined by later titration. Correction is made for CO. produced by respiration and for that in the eliminated gas. The method seems to insure reasonable accuracy. In agreement with other workers, BLACKMAN and SmitH find Elodea extremely sensitive to adverse conditions. A few days of storage in tap water in laboratory or greenhouse cuts the assimilation 17 to 30 per cent. The plant also endures great concentration of CO,. Water saturated from an atmosphere containing 30 per cent CO, does not interfere with assimilation; it is not likely that air plants would long.endure such concentrations. The points of large significance can be set forth by quotations from the summary of the second paper “The aim of this study is to demonstrate the mature of the relation between assimilation and the chief environmental factors: (1) CO,-supply, (2) light- intensity, and (3) temperature. The relation is such that the magnitude of this function in every combination o these factors is determined by one or the other acting as a limiting factor. “The identification of the particular limiting factor in any definite case is carried out by applying experimentally the following general principle. When the magnitude of a function is limited by one of a set of possible factors, increase of that factor, and of that one alone, will be found to bring about an increase of the magnitude of the function.’ e experiments in this paper deal with such moderate intensities of assimilation as may be fairly well maintained for several successive hours. - With more intense assimilation the values soon fall off by the action of internal factors grouped at present as the time factor. Experiments in which this additional factor has to be reckoned with will be considered in a later paper.”’ ” BLackMAn, F. F., and Smita, A. M., amare oe on vegetable accimi hanocec d respiration: VIII. Sue method for of submerged plants; LX. On assimilation in ahinens water planta and its velattoni to the Sica aseleel of carbon dioxide and other factors. Proc. Roy. Soc. London B 83:374-412. IQIt. 242 BOTANICAL GAZETTE [SEPTEMBER The work from BLACKMAN’s laboratory has done much to substitute a physico-chemical conception for the too general stimulus conception of the German plant physiologists. In this direction these papers again bring forth evidence for the non-existence of true optima, for the great importance of “limiting factors,” and for the significance of what BLACKMAN has designated as the ‘‘time factor.”—WILLIAM CROCKER. Cytology of the ascus.—The controversy to which the behavior of the ascus nucleus has recently given rise, has led GUILLIERMOND* to reinvestigate the bject. Contrary to the results of Miss FRASER??: 23, 24 and her coworkers, these new observations extend and entirely confirm his previous studies, and convince him that the number of chromosomes remains constant during the three successive mitoses of the ascus nucleus. He discusses the method of formation and the separation of the chromosomes of the first division, and whether there exists a second: numerical reduction during the third nuclear division. In all of the species studied (Humaria rutilans, Peziza catinus, Pustularia vesiculosa, Galactinia succosa), he finds that the number of chro- mosomes of the equatorial plate stage and of the anaphases remains the same, and that the distribution of these chromosomes is accomplished in the same way in all of these forms. As in previous studies, GUILLIERMOND?S: 2° believes that the process described by Marre??: 28 that is, a double longitudinal division of the chromosomes during the anaphases, which results in doubling the num- ber of chromosomes found in the ee plate stage, rests on incorrect observations. He also believes that Marre’s contention that there exists in the ascus of Galactinia succosa protochromosomes, which fuse into four definite chromosomes, is untenable. GUILLIERMOND holds that there are eight definite chromosomes and not four, which are formed directly and not from proto- chromosomes. These eight chromosomes are divided only during the meta- 2 GUILLIERMOND, M. A., Apercu sur l’évolution nucléaire des ascomycétes et nouvelles observations sur in mitoses des asques. Rev. Gén. Botanique 23:89-120. IgIo. 22 FrASER, H. C. I., Contributions to the cytology of Humaria rutilans. Ann. Botany 22:35-55. 1908. 73 FRASER, H. C. I., and WeEtsForp, E. J., Further contributions to the cytology of the ascomycetes. Ann. Botany 22:465-477. 1908. 24 Fraser, H. C. I., and Brooxs, W. E. Sr. J., Further studies on the cytology of en ascus. Ann. Botany 23:538-549. 1909. : UILLIERMOND, M. A., aoe sur la karyokinése des ascomycétes. Rev. om Sepsis 16:1-65. 190. , Remarques sur i karykinése des ascomycétes. Ann. Mycol. 3:344- 361. 1905. 27 Marre, R., Recherches cytologiques sur quelques ascomycétes. Ann. Mycol. 3: pe aae 1905. , Recherches sur la karyokinése chez les ascomycétes. Rev. Gén. Bota- nique pits esis. 1904. Igti]} CURRENT LITERATURE 243 phases, and not again during the anaphases. The exact manner of division of the chromosomes seems to agree with that described by Miss FRASER, but on the basis of certain stages, which he thinks were missed by her, he interprets his results in a different way. He describes a synapsis stage, whose loops correspond to the y-shaped chromosomes, which later appear on the spindle in the equatorial plate. Although he does not very strongly insist on this f ‘ scribed by FARMER and Moore for higher forms of plants and animals obtains in the ascomycetes. In the first part of the paper an interesting discussion of the state of these Aix and other problems relating to the ascomycetes will be found.—J. B. Overton. Anaerobic growth.—LeHMAN” has studied anaerobic growth in higher plants, trying to determine whether the view of WIELER or that of NABOKICH is correct. WIELER claims that the higher plants will not grow in total absence of oxygen, but that only a very low oxygen pressure is needed for growth. NABOKICH claims that higher plants will grow in absence of oxygen. He maintains, however, that proper nutritive conditions must be supplied, as in fungi. For this purpose a glucose solution is suitable. This solution certainly increases anaerobic growth in the pea seed, sunflower seedling, and other forms. In a later article, not cited by LEHMAN, NABOKICH® describes the course of anaerobic growth in higher plants. Soon after placing the organ in the oxygen-free medium, growth ceases (Vacuumstarre). Some- what later growth begins, and the rate rises until it equals that of aerobic growth. Still later growth ceases and death of the organ ensues. NABOKICH explains the course of anaerobic growth as follows: oxygen acts as a stimulus to growth, and not merely as an energy releaser, hence with its withdrawal growth ceases; intramolecular respiration later produces poisonous by- products, whith in low concentrations act as stimuli to growth, but which with further accumulations stop growth and kill the organ. The bad feature of this explanation is the indefiniteness of the term stimulus. NABOKICH finds that resting plant cells or those with low metabolic activity can remain in oxygen-free condition for long periods without injury. LEHMAN found only very slight if any anaerobic growth in Vicia Faba, Pisum sativum, Lupinus albus, Brassica Napus, Phaseolus multiflorus, and Cucurbita, ais in distilled water or glucose solution. In Zea Mays and Glyceria fluitans, anaerobic growth was marked in glucose solution, but was nil in distilled water. In Helianthus annuus, anaerobic growth was slight in distilled water, but considerable in glucose solution. LrHMAN concludes that anaerobic growth in any higher plants is not long-enduring nor considerable *? LEHMAN, Ernst, Zur Kenntnis des anaeroben Wachstums héheren Pflanzen. Jahrb. Wiss. Bot. 49:61-90 * NaBoxicu, A. J., Ueber die Wachabiusebies Beih. Bot. Centralbl. 26: 7-140. Iglo. 244 BOTANICAL GAZETTE [SEPTEMBER when compared with aerobic growth. He also finds no coincidence between intensity of “intramolecular” respiration and of anaerobic growth. e con- clusions of these workers are drawn from too few and these mainly cultivated forms. Study of wild forms of varied habits may show very different results. —WILLIAM CROCKER. Structure of the spore wall.—A notable addition to our aide of the structure and development of the spore wall is contributed by BEER in a study of the young pollen grains of [pomea purpurea. At the conclusion of the reduction division, the tetrads of young pollen grains become surrounded by massive mucilaginous walls, which show the reactions of callose and pectose. Within this mucilaginous wall, and surrounding each young pollen grain, i with th awkward and misleading term “special mother cell wall. e exine is deposited by the pollen protoplast upon the inner surface of the special wall, and at first is homogenous, but soon becomes differentiated into an outer lamella, with a network of thickening bands on its inner surface, and at the ‘intersection of the bands are the rudiments of the spines. At this stage a clear space is seen between the outer lamella and the thickening bands, and in this space the rodlets characteristic of the mature pollen develop. The spines project into the pollen cavity before they begin to appear externally. The intine develops within the exine as a thin layer, with thicker portions where it protrudes into the exit pores. Chemically, it consists of pectic bodies associated with some cellulose. In older pollen grains the exine consists of a delicate outer lamella perforated with countless pores, so that it really forms a reticulum with open meshes, beneath which are the thickening bands con- stituting the mesospore, perforated by the narrow exit pores for the pollen tubes. The outer lamella of the exine dips into the exit pores and covers the protrusions of the intine at these spots. Since nearly the entire growth of the rodlets and spines takes place after they have become separated from the protoplast, it is concluded that they are able to develop without any direct contact with the protoplasm. This short paper presents a thorough study of a single species and suggests a series of investigations, for it may be predicted with the utmost confidence that the account will not hold for angiosperms in general, and the author makes no such claim. After various types of pollen grains have received similar attention, it will be time to generalize—CuartEs J. CHAMBERLAIN. Chemotaxy.—SuiBaTa* gives the first part of a full statement of his exten- sive work on chemotactic responses of the spermatozoids of pteridophytes. This 3 _ Rupotr, Studies in spore development. Ann. Botany 25:199-214. pl. 13. 19 3? SurpaTa, K., Untersuchungen iiber die Chemotaxis der Pteridophyten Sper- aaa “Jah b Wiss. Bot. 49:1-60. 1911. \ 191i] CURRENT LITERATURE 245 part deals with positive reactions, while the second part will deal with the negative. SHIBATA himself has contributed no small part of the knowledge in this field, especially with the forms Isoetes, Salvinia, and Equisetum. The paper is divided into seven sections dealing with the following phases of the subject: (1) introduction and methods, (2) action of organic acids, (3) action of metallic ions, (4) action of H and OH ions, (5) action of alkaloids and other organic bases, (6) application of the Weber-Fechner Law, (7) the classes of chemotactic sensibility and their relation to each other. h of facts is so great that no statement of it can be attempted here. Some of the generalizations, however, especially those derived from the seventh section, are of considerable interest. SurpatTa concludes that there exists in the pteridophytes three categories of positive chemotactic sensibility: (1) for the anions of malic acid and of the related dicarboxyl acids, (2) for the in t same category one member dulls the action of any other. In general, the ulling effect is proportional to the attractive value, but this is not always the case. Citrate, which is 1/10 as powerful in attracting Salvinia sperms as is maleate, is just as effective in dulling the action of maleate as is maleate itself- SHIB t found no dulling action between any two chemotactically active substances.— WILLIAM CROCKER Coremia formation by Penicillium.—By methods which at the present stage of plant physiology appear somewhat crude and superficial, WACHTER’ has attempted to find the factors influencing the formation of coremia in a orm of Penicillium, which he designates by the usual name of P. glaucum, but which can be easily identified as P. expansum Link. The method of study consisted in growing the fungus on sterilized slices of various fruits and vege- tables, and on the expressed juices of these, and also on an inorganic nutrient solution with various concentrations of sugar, this being the only medium approximating anything like known conditions. When the results are sifted, we are left in the same position as before as to the factors which influence the formation of coremia, namely, that when grown on various substrata of unknown composition this form (like other coremia-forming species) some- times forms coremia and sometimes not, a fact, moreover, clearly formulated Se THOM in regard to this and other species of similar habit. The work o 33 WACHTER, ve peepee die Koremien von Penicillium glaucum. Jahrb. Wiss Bot. 48:521~-548. 34'THom, CH. ee eres, of species of Penicillium. U.S. Dept. Agr., Bur. Animal Industry, Bull. 118 246 BOTANICAL GAZETTE [SEPTEMBER Tuo, however, came to the author’s hands only in time to be noted in the proof. A closer approximation to definitely known conditions, if not yielding positive results, might at least have resulted in excluding certain groups of factors as having no influence on the formation of coremia. In the latter part of the paper, the author distinguishes 11 forms of Penicil- lium by their growth characters on the substrata which he used in the first part. The forms are not further characterized nor identified with other descriptions. The author lays stress on cultural characteristics, and the utilization of the coremia-forming habit for separating the species of Penicil- lium. Both have been used by Tom in his partial monograph of the group. —H. HASSELBRING. Feed containing smut spores.—The feeding of grain products containing large quantities of smut sporés to animals has usually been regarded as per- nicious, both on account of the widespread — supposed to be based on practical experience, that the smut spores are injurious to animals, and on account of the danger that the spores pass faced through the animal body and, as asserted by BREFELD, become a source of infection when they are distributed over the fields in manure. These questions have been reinvesti- gated by Honcamp and ZIMMERMANN, who as a result of feeding ESRI : which large quantities of smut spores, mostly of Tilletia caries with som T. laevis, were fed to different domestic animals for long periods of as e; came to the conclusion that in no case could any injury be definitely attributed to the smut spores. The spores which had passed through the bodies of animals, with rare exception, were incapable of germination. Fur experiments showed that sound spores mixed with manure or other fertilizers and scattered over the soil rarely cause infection of grain. These experiments indicate that the danger of infection from smut spores scattered over the fields in manure has been largely overestimated. This is true more particu- larly of the spores that have passed through the animal body. The only source of infection to be regarded of significance in agricultural practice is that from the spores adhering to the seed grain, a fact which may be inferred from the almost total prevention of smut by treatment of the seed grain.— H. HaASsELBRING. Temperate plants in Helgoland.—Since the spring of 1904, KucKUCK has been experimenting with the introduction into Helgoland of various species of plants of warm temperate climates.%* Although situated but 30 3s Honcamp, FR., und ZrmMERMANN, H. (unter Mitwirkung von G. SCHNEIDER), Untersuchungen iiber das Verhalten von Brandsporen im Tierkérper und im Stall- diin: r. Centralbl. Bakt. II. 28:590-607. 1910. os , P., Ueber die Eingewohnung von Pflanzen wirmerer Zonen auf oe ‘Bot Zeit. 68%: 49-86. pis. 1-3. figs. 2. 1910. Igtt] CURRENT LITERATURE 247 km. from the mainland, this island enjoys many of the features of an insular climate. February, the coldest month, has a mean temperature of only 1°34 C., and the lowest temperatures of the winter seldom exceed —8° C This is much milder than the climate of the mainland, but less genial than that of the southern coast of England. Notwithstanding the favorable temperatures, many plants are injured by the severe and incessant winter winds, and by the lack of a protective covering of snow. Kuckuck describes his results in detail, indicating the successful culture in the open of a large number of species, including such plants as Pittosporum Tobira, Camellia japonica, two species of Fuchsia, and various opuntias. Perhaps the most noteworthy of them is the fig, Ficus carica, which has been cultivated on the island for thirty years, attains a height of 4.5 meters, and matures fruit regularly. Kuckuck considers in general that the winds are more hostile to plant life than the frosts, and believes that other species might prove hardy if they could be given soils better suited to their requirements.—H. A. GLEASON. Twining.—NIENBURG?’ has made a detailed study of the nutation move- ments of young twining plants in their early stages of circumnutation. He believes that all the circumnutation and twining movements can be explained by the joint action of autonomic nutation and negative geotropism. He also believes that he has entirely disposed of NoLt’s conception of lateral geotro- pism. A careful analysis of his results, however, shows that lateral geotropism will also explain all movements he describes, with the possible exception of one on the centrifuge. The strongest evidence for NoLL’s conception was gained from the use of the centrifuge, and now with a slight alteration of the position of the plant NrENBURG obtains results on this instrument that seem to disprove Nout’s conception. NIENBURG’s centrifuge experiments have their main value, however, in showing the need of further centrifuge snes in this field—Wititam CROCKER. Amphibious polygonums.—A recent paper very plainly shows that exten- sive experimental cultures will be necessary before the taxonomic and ecological relationships of the various species of Polygonum can be settled. NreuwLAND* distinguishes at least three closely related species of this interesting genus which exhibit both an aquatic and a terrestrial form, but adds no experimental data to our present scanty fund. The species described vary so mu response to varying conditions of habitat that it seems possible that all these forms, with intermediate gradations, might be produced from the same stock by careful methods of culture. An interesting historical résumé of the litera- 37 ek oe Die Nutationsbewegungen — Flora 102; I17-1 46. 38 ies: J. A., Our amphibious Persicarias. Amer. Midland Naturalist 2:1-24. IQII 248 BOTANICAL GAZETTE [SEPTEMBER ture shows that our knowledge of the ecology of these plants has advanced but little beyond the observations recorded by JoHN Ray? more than two centuries ago.—GeEo. D. FULLER Syndiploid nuclei.—Nuclear figures in chloralized root tips, described by NEMEC, then by STRASBURGER, and then discussed and figured at some length in NEmec’s recent book on fertilization, have been reinvestigated by STRAS- BURGER.” He used again the root tips of Piswm sativum, and made a critical comparison of the nuclear figures in normal and chloralized tips, and compared the peculiar mitoses of syndiploid nuclei with the normal heterotypic mitoses of the same species. He agrees with NEMec that the syndiploid nuclei grad- ually disappear, but denies that any heterotypic mitoses are concerned in the disappearance. NEmec’s figures, intended to support the theory of a somatic heterotypic mitosis, are discussed and explained as only peculiar vegetative mitoses, with merely superficial resemblances to genuine reduction divisions. —CHARLES J. CHAMBERLAIN Structure of protoplasm.—During the last decade cytologists have been so busy with various phases of the chromosome problem that little attention has been given to the structure of protoplasm. A preliminary announcement by LEpPESCHKIN* is entitled ‘On the structure of protoplasm,” but this paper deals with artificial emulsions rather than with protoplasm itself. e prin- cipal conclusion is that streaming protoplasm cannot have the foam structure described by Btitscuir, but rather has the structure of an emulsion. He admits that the peripheral layers of protoplasm in infusoria may have a foam structure.—CHARLES J. CHAMBERLAIN. Peat bogs in Iowa.—A comparison has been made by PAMMEL* between the t bogs of northern Iowa and those occurring in other parts of the United States. The principal types found in this state are the aspen bog, ow bog, sedge bog, and rush bog, none having a very extensive develop- ment. The sphagnum bog is conspicuously absent. A detailed comparison of the bog flora of Iowa, Wisconsin, and Michigan shows that in Iowa many of the typical bog plants of more northern regions are replaced by others of a very different character—Gero. D. FuLter. 3? Ray, JoHN, History of plants. Vol. I, p. 185. 1686. 4° STRASBURGER, EpuArp, Kernteilungsbilder bei der Erbse. Flora 10221~-23. pl. 1. 1911 4* LEPESCHKIN, W. W., Ueber die Struktur des Protoplasmas. Ber. Deutsch. Bot. Gesells. 29:181-190. 1911. # PAMMEL, L. H., Flora of northern Iowa peat bogs. Iowa Geol. Survey 19: 739-784. 1909. For the restoration of energy; if/ the relief of mental and nervous exhaustion, and to give ome a good appetite there is nothing so beneficial as Horsford’s Acid Phosphate ( dee: alcoholic. ) »Providence,R I, Rumford Ct The Typewriter That’s Ten Years Ahead Is the Typewriter for You. THE L. G. SMITH & BROS. TYPEWRITER With Ball Bearings throughout and all the writing » Measures up at every point ‘to the highest scale of modern needs. Better work and more of it, greater efficiency through and through, the L. C. Smith & Bros Typewriter is ue writing machine oe you. Send for the Book today. L. C. SMITH & BROS. TYPEWRITER CO. Syracuse, N. Y., U.S.A ENNEN’ Borated Talcum FOR MINE For Prickly Heat and Sunburn Relieves ail Skin Irritations Sample Box for 4c stamp GERHARD MENNEN CO, : Newark, N. J. Trade-Mark Intending purchasers of a strictly first- class Piano should not fail to exam- ine the ‘ merits passed tone-quality, unequaled ae pe ee ele- —— ailed gance of me on applica’ THE SOHMER-CECILIAN INSIDE PLAYER ti hepa oo peaalnie and finish. Catalogue m Favorable -Term ible Parties SOHMER & COM PANY . 315. 5th Ave., Cor. 32d St B &L.O.CO OCULAR DEMONSTRATION is more convincing oS Mita precept. Have you a microscope at command—the most valuable Stacarcniel adiunc in Physiology, Zodlogy and Botany classe Bauscl lomb Microscopes have accomplished important work in most of the leading schools and colleges in the country. Our BH-2 is specially made for class work. It has a 7.5X eyepiece, 16mm nd 4mm objectives, with lock and key. eae Meritline 75 and 320 diameters. Price ace Special prices to schools Write today _ particulars —_ free booklet, ““A Manual of Elementary cease opy Address Dept. 7D name, backed half a century of experience, is on Re products — lenses, — ans 4 glasses, “laboratory taba neering entific ments, Bausch 6 lomb Optical 6. LONDON. “ROCHESTER. NY. FRANKFORT Free Trial As a busin : appeal ie oe nef purchase type better typevr —not merely“ ‘just = certainly do not want you to kee For 20c a Day Sewerin ONE PERFECT VISI- If p me a little down, prea pony the balance atthe rate f rie oo a day—no payments on Sundays and H The rae . visible—sou do not have to look beneath a lot of proving he! bars to sec whatis written! [t has ack Spac ap ha bulator, Two: easy or Gee fe Key speediest operator, idee enouah, so the beginner— It is a mely Dura and almost Nolssices Let Me Help vie xen let me help te NEL TED Send for Catalog and Other Advertising bon spony Fo ox x Type yee tes Front St., Gran ianlan. Mich. will return the’ typewriter I decide not to purchase It ee ni SE Address____ Business For those who KNOW Drawing | Eternal Writing Ink 85 En Higgins’ faeries uid ice Paste Neaetubte Glue, Etc. Are ie Finest and Best Inks and Adhesives —_ ¢ yourself from the use of corrosive and fle ae ry inks and op vi and adopt the nag gins and Adhesive They will be revelation to you, they are Pe sweet, clean, eel put At Dealers inssniay. CHAS. M. HIGGINS & CO., Mfrs. Branches: Chicago, London 271 Ninth Street. Brooklyn, N. Y. 8 FINE INKS 42 ADHESIVES ‘No More Hand ea Writing Calculating Both are eliminated by the Remington Adding and Subtracting Typewriter (Wahl Adding Mechanism) VISIBLE ld VISIBLE WRITING = ADDING Remington Typewriter Company ITALIAN BOOKS every description ITALIAN ee Boo che ak ab te ‘secu TO bith terse Sed a ca, aches Sag Castelnuovo, or aterion mailed on application. BRANCH 147 MULBERY meer PAT. PAPER AX. ” PASTENERS the past YEAR SOLD ood SOnrty YOU of their ; “they alu . 3 sizes. Put upin brass Png sot 100 Famen work. No Shopping, | NEVER see on coy fastener id 10¢ rn r , assort i booklet free. «foram Seiaunt tothe trade. — e 0. K. Mfg. Co. , Syracuse, N. Y., U.S. A. ) AND UP $2.30 AN THE ORIGINAL NON-LEAKABLE FOUNTAIN PEN) The Pen Point is Always Moist. ° a o - a 4 edeees o a rad eakable carries the most end d liner guarantee. € CHOOSE MOORE’S FORITS QUALITY For Sale By Dealers Everywhere. AMERI CAN FOUNTAIN PEN (0 Qdams, Cushing b ring a — 168 DEVONSHIRE ST.. CANADIAN AGENTS, W.J. GAGE sr cn. ToRRTR.O ee EVER NEED DUPLICATES _ Of Form Letters, Price Lists, Bills, Invoices, Drawings, Menus. Rep rs ANYTHING ? Then take advantage of our offer ra 0 DAYS TRIAL, WITHOUT DEPOSIT and tea Ar of iiiainats of satisfied customers who all agree that Daus’ Improved Tip Top Duplicator is the simplest, easiest, and quickest method of dupli icating_on the market. .100 copies from Pen-written and 50 copies oom Type- Ww ita Original. machine contains a continuous roll of our “Dau Oiled | Linen Back audicatinr surface which can ie reed ov a ve over again. If you have tried other Gina ators without success, ou will be et ple ie wi Ae Net Price FELIX F. DAUS DUPLIGATOR COMPANY, Daus Bldg,, 111 John St., . NEW YORK ne Complete Duplicator, Ca) o- (prints 83x13 inches). $500 ORIGINAL— GENUINE Delicious, Invigorating 9¢ MALTED MILK The Food-Drink for all ages. Better than Tea or Coffee. Rich milk and malted-grain extract, in powder. A quick lunch. Keep it on your sideboard at home. IMS Avoid Imitations— Ask for ““HORLICK’S’’— Everywhere ; 6 The University of Chicago Press FOREIGN AGENCIES FOR BOOKS AND PERIODICALS British Empire THE CAMBRIDGE UNIVERSITY PRESS Fetter Lane, London, E.C., England Continental Europe TH. STAUFFER Universitatsstrasse 26, Leipzig, Germany Japan and Korea THE MARUZEN-KABUSHIKI-KAISHA 11-16 Nihonbashi Tori Sanchome, Tokyo, Japan INQUIRIES AND ORDERS WILL RECEIVE PROMPT ATTENTION ee ITE GR ha TIE i Se irr eho TPS H. MICHAELYAN © 2om'sr. New york OME of the readers of this Periodical may be under the impression that Oriental rugs are luxuries whose attainment borders on guilty ex- travagance. @ We are in a position to prove the contrary. For $20.00 or $25.00 we will send you a Persian rug on thirty days’ trial, at the expiration of which period we will refund the money if the rug is returned. @ The size of the rugs are from 6 to 7 feet long and from 3 to4feetwide. Thecolors desirable. If you’ have an old rug to replace with a good Oriental, or a bare corner in your home to beautify, or if you wish to make a lasting, suitable gift, we would sug- gest that you send for one of these rugs. q@ Kindly state if $20.00 or $25.00 rug is desired, and give the size and color you prefer, and we will select a piece as near to your requirements as possible. @ Visitors to New York welcomed. Correspondence upon matters pertaining to Oriental rugs invited. 7 The University of Chicago Press Announces that a representative stoch selected from its list of books and pamphlets is carried by The Baker and Taylor Company 33 East 17th St., New York, N.Y. Patrons located east of Buffalo and Pittsburgh will effect a material saving in time by placing their orders through this agency. EXTBOOKS for the graded Sunday school, for religious education in schools and _ colleges, and for individual study of the Bible are published by the University of Chicago Press. They comprise 37 volumes, providing material for every grade of students, from the kinder- garten to the college. Put yourself in touch with the editors, authors, and publishers of this series and ob- tain the advice of experts in grading your Sunday school, or in selecting textbooks for day school, study circle, or home use. : Send for the new handbook of 150 pages, giving specimen pages from all books and much valuable information about graded work in religious education. The University of Chicago Press Chicago | . - Illinois Learn to Breathe Every Singer should learn to breathe properly and thus increase capa acity for work and reduce fatigue to a minimum THIS NEW VOLUME WILL TEACH YOU RESONANCE IN SINGING AND S ING by DR. THOMAS FILLEBROWN Twenty-one pap Bare be 1 9 92 Oral gery in Harvard Un rsity For Singers, Speakers, and all who ner to improve the quality of the voic PRICE, POSTPAID~ - - $1.25 is hardly too egg! to say that if teachers and important, not only to students of singing who have to become professional oo Ate 9 to all who wish to enjoy perfect health . Finck, in The Nation of Fe say" a OLIVER DITSON COMPANY remont CHAS. H. DITSON & pong 8-10-12 East 34th Street NEW YORK CITY Paleo Styles The name ‘Esterbrook’”’ stands for all that is best in pens. The standard of the world. All styles—fine, medium and broad points. Ask your stationer, The Esterbrook Steel Pen Mfg. Co. 95 John St., New York Works: Camden, N.J. WESTON ALTERNATING CURRENT SWITCHBOARD H ETERS AND VOLTMETERS will b found vastly “a instrument in- ended for the same so | Dead Beat, and Ex- service hey are Abso tren rely alee: Me ve, - Practically Wie from temperature Error. They require extremely aa power to operate them and they are very lov Cor esfon Ww ést Z WESTON SEECTaAL INSTRUMENT COMPANY NEWAR nde CE ee ee os sé solic 4 Si ben — : Audrey House Stiy Place, Holborn. Parts, Faance i: E, H, afi be eM" George es, BERLIN: Weston In ecb eon Co. , Schineberg + 5. JUDS® * FREIGHT FORWARDING CO. Rageern: vee mage hy Marquette Bldg St. 1S, 1501 me Los Angel ngeles ee Central Bldg. Boston, 736 Old South Blac, San Francisco, 217 Front St. fork, 342 Whitehall Building HIGHEST in | QUALITY, SMOOTH- NESS ano FLAVOR & CHOCOLATE ror CHOCOLATE CONNOISSEURS — “TEN CENTS &. ee CENTS. SOLD EVERYWHERE GOODE’S BASE MAPS a series of outline maps for all classes of work in applied sciences and the various fields of research Prepared by J. PAUL GOODE Associate Professor of Geography in the University of Chicago This series is designed to meet the needs of teachers and students ina wide variety of work with maps. The maps are adapted to the use of classes of every grade, from the university to the common school: in geography, including commercial or economic geography, in choralogcenice: geology, botany, zodlogy, anthropology and ethnology, sociology, econom- ics, politics and history. e maps have been prepared by being first drawn on a large scale, to insure accuracy of detail, and then greatly reduced in the engraving. the quality of the drawing they are superior to most maps used in books and magazines. In two Sizes 8 x 103 in., 1 cent each 15 x 103 in., 3 cents each No. 1. The World: on Mercator’s projection. No. 14. No. 2. ape ag a on an equal-area pro- o. 16. ject The British Isles: conic projection. Europe, Western and Southern: conic projection. France: conic projection. No. 3. South Reins Sanson’s projection. No. 17. No. 4. ree conic projection. No. 18, The become fixed and transmissible. A perfectly a, graded series of parasites may be selected : which exemplify all stages of dependency, atro- phies or reductions, and adjustive arrange- ments; but nothing may be assumed as to the manner in which progress has been made from one stage to another. It seems fair to conclude, however, that the evolu- tionary movement is generally toward in- creased dependency of the parasite, ac- companied by ac- centuated and more complete atrophies. The view that such a movement may some- times ultimately lead to extinction, al- though by a long and indirect way, seems also justifiable by in- ference, although such an end must not be assumed for all groups of parasites. 1.—Cissus laciniata parasitic on Tse Blakeana; the host has been a to expose the roots of the xeno- KaxMovtes parasit Igtt] MACDOUGAL—PARASITISM 251 In the experiments carried on at the Desert Laboratory from 1908 to 1911, the desert grape (Cissus laciniata) of Mexico, the expressed juice of which shows a pressure of over 11 atmospheres, was found to maintain itself on the flattened joints of Opuntia Biakeana at about 9 atmospheres; not so successfully on Echino- cactus Wislizeni, the drinkable juice of which has a concentration equivalent to about 6 atmospheres; while it soon perished when attached to stems of the great tree cactus (Carnegiea gigantea) at less than 7 atmospheres (fig. 1). The last named plant exudes an acrid fluid from fresh wounds, which are quickly closed by the formation of heavy, corky layers. Opuntia versicolor, a species with cylindrical stems showing a pressure of 12 atmospheres, was able to draw supplies for extended periods from Carnegiea and the other hosts mentioned. Plantlets of A gave were equally effi- cient, although this xeno-parasite formed such a great number of Foots as to destroy the tissues of the host plant. Cissus also formed roots which penetrated the host, while the absorptive contact of Opuntia (flat-stemmed) was by the epidermal cells of the stems in every case examined. The briefest inspection of the results of the analysis of plants used in these experiments, shows that the direct proportion of mineral salts in the sap and the acid contents of the sap have no direct bearing on possible parasitism among the higher plants." The relation of seasonal cycles, capacity for development of absorp- tive elements de novo, and an accommodative adjustment of the Osmotic pressure of the cell sap are to be mentioned as factors in the making of nutritive couples. The greater number of the para- sitic arrangements made are to be included with the root parasites. A few additional experiments were set up to test certain points after the completion of the manuscript printed in 1910. The results of these and of the continuation of older preparations seem to warrant the presentation of this additional note on the subject. May 11, r910.—A number of beans of a mixture of species native to the deserts of southern Arizona were attached to joints ‘See MacDovcat and Cannon, The conditions of parasitism in plants. Publ. No. 129, Carnegie Inst. of Wash. 1910. 252 BOTANICAL GAZETTE [OCTOBER of prickly pear, with the radicles thrust into cavities in the soft tissue. The bean was held in place by a setting of plaster of Paris, and a moist strip of cloth was brought from a vessel of water to furnish moisture until the plants should become established in their new relations. May 13.—A large number of new insertions of the “‘rusty”’ bean in joints of Opuntia and bodies of Carnegiea and Echinocactus were made on this day. Some of the original preparations were showing notable growth. May 14.—Some of the plants first arranged had thrust the tips of the plumules beyond the cotyledons, but had not yet straight- ened the hypocotyl. One bean with wilted plumule was taken out of the Opuntia. The main root had grown but little. A secondary branch from near its base had come out and extended . down into the cavity, alongside the main root, showing as great a length. May 22.—Twelve seedlings on Opuntia had survived, of which one had developed the plumule to an extent that the leaves were unfolding from between the cotyledons. Six seedlings on Echino- cactus had survived, and were showing some slight development. Three seedlings out of g insertions on Carnegica had survived and had made-.a slight development. The cotyledonary curvature was still markedly present. May 31.—Temperatures of 111° and 112° F. out of doors, and all parasites were flagging, apparently dying. All soon perished. About a dozen germinated beans of the form known as ‘small Papago white” were inserted in joint of ‘‘Mission Pear” (Opuntia sp.), near the laboratory at Carmel, California, on June 23, without any protection except a cloth shade. These, with the exception of two, dried out, although small secondary roots were formed by June 27. All were replaced and a small vial was arranged with a strip of cloth to give shade and moisture. About 8 similar preP- arations were arranged on Oenothera biennis and O.H 206. On July 1, only one of this lot had become dry, the fogs of the pre- ceding days having been an obvious advantage. July 14.—Seven Papago white beans on Mission Pear thriving. of which three had well developed leaves of the first simple pair, Igit] MACDOUGAL—PARASITISM 253 and one showed a second pair. The others still retained the plum- ule partly between the cotyledons. August 2.—All beans were dead or nearly so. All of the devel- opment in these plants was undoubtedly carried on at the expense of material in the cotyledons; and the roots soon perished after being immersed in the mucilaginous tissues of Opuntia or the stems of Oenothera. The high humidity of the fogs and low temperatures ranging between 45° and 65° F. also made for the endurance of the seedlings. These tests are chiefly interesting in contrast with the cultures of Prrrce, in which plants of Pisum salivum were grown on stems of Vicia Faba to maturity. The advantage of the aeration of the roots in the central cavities of the stems of the host and also of one legume parasitic upon another, doubtless accounts in large measure for the success of ' these cultures. The completion of the original manuscript on this subject left several preparations in good condition, which were two years old. Among these were Opuntia Blakeana, O. versicolor, O. arbus- cula, and O. leptocaulis on Carnegiea; O. leptocaulis on O. discate; also one Agave americana on Carnegiea. Some of these parasites remained alive throughout a part or all the year, it being noted that those shielded from direct illumination by the body of the host survived longest. March ro11 found arrangements of Opuntia versicolor, O. Blakeana, and A gave on Carnegiea. All these preparations were made with plants as xeno-parasites Which were characterized by a water balance of some amount and by an osmotic pressure of the sap of 9-12 atmospheres. Further- more, the survivors were held in place by a mass of plaster of Paris molded about the bases of the stems which held the roots closely appressed against the corky tissues of the host. This state of affairs may be seen to furnish a fair approximation of the physical conditions under which an Opuntia was found with the roots in a small cavity in the trunk of a Parkinsonia, and of the Same species in a cavity in the summit of a trunk of Carnegiea.° A further illustration is offered by a case photographed and reported * Peirce, G. J., Artificial parasitism, etc. Bot. Gaz. 382214. 1904. 3 See Publ. No. 129, Carnegie Inst. of Wash. t1gTo. 254 BOTANIC ‘ TANICAL GAZETTE [OCTOBER ar Tehaucan, —Cissus lac Mex.; winiala and O ; an epiphytic bromeliad is puntia growing from sin 3 attached to one of the ter ne C ane mE minal joints of th e Opuntia. tgit] MACDOUGAL—PARASITISM 255 by Dr. W. A. Cannon, in which a flat-jointed Opuntia was found established in a cavity in the trunk of an Acacia Greggii. One or more species of Opuntia native to the Tehuacan region find a foot- hold in the crevices of tile roofs,.and stone and adobe walls, in a very noticeable manner; and it was in this vicinity that one of these plants and a native grape were found rooted in the sinus of a forked tree Yucca (fig. 2). The conditions of such association seem favorable for the slow extraction of solutions from the host plant through non-living tissues without the actual contact of the living cells, an approxi- mation to the initial conditions of parasitism. It is obvious that the crowded root systems of a wide physiological variety of plants in the soil furnish numberless duplications of these conditions, and it seems entirely reasonable to suppose that such contiguity of absorbent and succulent roots may acccount, in part, for the greater number of root parasites. It is to be noted that among the higher plants the part played by destructive secretions is at a minimum. The activity or absence of such substances in seed parasites has been variously described. In no instance, however, are there such abundant and disintegrating effects as may be seen resulting from bacterial and fungal parasites of plants and animals. The parasitic arrangements described above, in which the host furnishes lodgment and a slowly yielded supply of solution, are characterized by a slow growth of the parasite, in which the amount of development is limited, the members being reduced. The Opuntia parasitic on Parkinsonia, which was described in Pub- lication No. 129, Carnegie Inst. of Washington, rg1o (see pl. 10), was taken from the host early in 1910 and set in the adobe soil of the terraces in the courtyard of the Desert Laboratory. In the course of the growing season of that year, it made three new joints, each of which was three or four times the bulk of those previously formed, the total growth in the previous 7 or 8 years. F urther- more, in this autophytic growth it developed characters which demonstrated that it properly belonged to Opuntia Toumeyi instead of O. Blakeana, with which it was first identified, because of its small joints and atrophied spines (fig. 5). 256 BOTANICAL GAZETTE [OCTOBER The Opuntia versicolor which had been fastened in a cavity in the side of a tall Carnegiea early in 1909, lost three of its four short branches and the terminal section of the stem during the dry foresummer of 1910. Activity in the rainy season in the midsummer following resulted, not in the formation of additional sections or members, but in the increase in thickness of the stem FIG. 3.—Opuntia versicolor parasitic on Carnegiea gigantea, March 1910 and roots; the latter were thin and fibrous when the preparation was made, January 23, 1909. After two years of parasitic exist- ence, the visible portions of the root system were much enlarged, after a manner sometimes exhibited by autophytic individuals of the same species (figs. 3 and 4). An Opuntia Blakeana set in a cavity of Carnegiea, where it was held by plaster, early in 1909, likewise formed no additional 1git] MACDOUGAL—PARASITISM 257 members during the following two years. Some thickening of the cylindrical basal segment, however, was noticeable. The work described in this and previous papers has been suc- cessful in the demonstration of certain physical conditions which make parasitism possible, and has led to the suggestion of physi- ological activities which limit or facilitate the adhesion of two seed plants in a dependent nutritive combination. Wider observations would doubtless increase the known parasitic combinations, while it may be safely assumed that present conditions are as favorable for their making as at any time in the history of the plant world. New parasites may be expected to be brought to our attention from time to time. The assumption of a mutualistic or depend- ent role, in fact any de- parture from a purely autophytic condition by a green plant, is inevi- tably followed by reduc- tions or atrophies. Such Fic. 4—Same plant as in fig. 3, March rotr, with enlarged roots and stem, and with but one surviv- ing branch. combinations are displayed by a number of seed plants, not far short of half the existing species. It is of interest to note that the parasiti- cal consequences have not yet been seen in green plants furnished With food material including organic compounds. The total reaction is complex, and the exciting ‘causes are probably not simple. Whatever they may be, they are furnished only by the living or decaying bodies of other organisms. The part played by the pathological effects and physiologic reactions of parasites in 258 BOTANICAL GAZETTE [OCTOBER the evolutionary development of plants has never been adequately portrayed, even in a speculative manner. The vigor of growth, widely varied capacity for reproduction, range of endurance to unfavorable conditions, and accommoda- tional adjustment displayed by parasitic fungi and bacteria in general seem to place the greater majority of these forms in a Fic, 5.—Opuntia Toumeyi; this plant was found growing in a cavity of the trunk of a small tree of Parkinsonia microphylla in 1906, and the small joints formed during its parasitism are to be seen near the base and to the right; the larger joints were developed after the plant began an autophytic existence rooted in the soil; photo- graphed February rort. Igtt] M ACDOUGAL—PARASITISM 259 position where the only obvious way to extinction would be by the destruction of their hosts, resulting from their own effective- ness. Nothing known of the life history of any of these forms suggests a possible aban- [ — donment of the parasitic | habit and of an advancing morphological develop- ment. So far as the higher plants are concerned, the only consideration hitherto given to parasitic forms has been to view them as pass- ing down an inclined plane of atrophies, which would ultimately lead to their ex- tinction, without reference to the abundance of devel- opment of the host forms. No hint has yet been ob- tained as to the possibility of a retracement, by which a dependent might once more regain its standing as an autophyte. Regressive action of this character would naturally be discernible only in a Series of material extend- ing over long periods of time, such as that obtained by the paleontologist. It is interesting to note that this subject is one to which some serious attention has been given, and Dr. J. M. CrarKe* has recently summarized the information with regard to the case of the limpet and the —Cissus laciniata parasitic on Fic. Opuntia Blakeana (see fig. 2). a 4 The significance of certain early parasitic conditions. Science 33:291. TQTT. 260 BOTANICAL GAZETTE [OCTOBER crinoid of earlier times and the gastropods and sea urchins of the present. It is made clear by CLARKE that the limpets of the early Silurian were largely parasitic on the crinoids, a habit that per- sisted for millions of years, until the closing stages of the Paleozoic, when evidences of it were lost, and no traces of parasitism of snails on the few crinoids of the present are known. Other gas- tropods of the limpet structure are now parasitic on the starfish and sea urchins, close relatives of the crinoids. The earlier lim- pets were not carried beyond the stage of possible regression in their parasitism, but the modern parasitic gastropods are ‘often so modified by their degeneracy that their nature is hardly recog- nizable, and this parasitism is fixed and beyond repair.” Two separate cases of adaptational adjustments seem involved, and the parasitism of the modern gastropods is taken to be wholly independent of the earlier assumption and abandonment of the habit. The suggestion lies near, however, that a family which has thus furnished two separate series of parasites is one which by morphological characters or physiological tendencies is liable to assume dependent relations with other organisms as hosts. Parasitism among the higher plants of the present time is con- fined to ten families, one of which has been added recently to the list by the work of Dr. W. A. CaNnNon. It may be safely assumed that in some of these, the Orobanchaceae, for example, the habit is far beyond retraction. Desert LABORATORY Tucson, ARIZONA CONTRIBUTION FROM THE ROCKY MOUNTAIN HERBARIUM. IX NEW PLANTS FROM IDAHO AVEN NELSON Most of the plants considered in this paper were collected in Idaho. Since they were secured during a single season by an amateur, a word concerning the collector and the field investigated will not seem out of place. Early in 1910 specimens were received from J. Francis Macsripe for determination. In the corre- spondence that developed it was soon apparent that he was a close observer and deeply interested in the flora of his neighbor- hood and state. A proposition from him to collect for the Rocky Mountain Herbarium led to the discovery that he was a boy just out of the Boise High School. An agreement was soon reached whereby he was to undertake field work in some part of Idaho. To determine the least worked and therefore the most inviting - field, appeal was made to the two men who probably know the flora of the state better than any others, namely the former pro- fessor of botany at the University of Idaho, L. F. HENDERSON, and Professor Ext1as Netson of the Experiment Station. These Were agreed that southwestern Idaho was practically unexplored, that name. Their judgment has been confirmed by the work thus far carried out, and further collections in this very interesting field will be made in Igit. Ertoconum ovatirotium Nutt.—As the collections of this so- called “aggregate” species multiply, the probability increases that the seemingly quite distinct forms of it represent but one very variable species. The type of the species was the comparatively small yellow-flowered form. Then Nutra gave us E. purpureum, differing in no respect except in color. It has since been shown that between the two the specimens show all shades of yellow to white, and white to purple. At most then, NuTTatt’s second species 261] [Botanical Gazette, vol. 52 262 BOTANICAL GAZETTE [OCTOBER ought not to be recognized as more than a variety, and as a recog- nizable though not necessarily permanent variation. What is true of E. purpureum Nutt. is equally true of three of SMALL’s segregates. They are based on no permanent characters, since in this genus color and size have been shown to vary with every change in the ecological factors. Two of these species, E. ochroleu- cum and E. orthocaulon, occur in the semi-arid portion of the Snake River basin and its tributaries. They may grow inter- mingled in the same district, as was the case in the superb specimens mentioned below. I therefore propose one varietal name to repre- sent the two as follows. ERIOGONUM OVALIFOLIUM celsum.—E. ochroleucum Small, Mem. N.Y. Bot. Gard. 1:123. 1900; E. orthocaulon Small, Bull. Torr. Club 33:53. 1906. MACBRIDE’S specimens, soon to be distributed under this varietal name, represent well the two colors, the oval to oblong leaves, and the tall scapes. New Plymouth, Idaho, May 21, 1910, nos. 85 and 86. ERIOGONUM OVALIFOLIUM vineum.—E. vineum Small, Bull. Torr. Club 25:45. 1808. Besides the wine-colored flowers, this is more noticeably tomentose, hence may be kept distinct from the preceding variety, though like that it merely represents the species in its maximum development. Stanleya rara, n. sp.—Inflorescence inordinately crowded, becoming 4 or more dm. long, the rachis only moderately stout: pedicels about 1o mm. long, in fruit 15-20 mm.: sepals yellow, linear, about 10 mm. long and 1 mm. or more wide: petals yellow, linear, narrower than the sepals and about three times as long; the claw longer than the sepals and but little narrower than the blade: anthers 3-4 mm. long, at length well exserted and more or less curved or coiled: ovary at full anthesis about 4 mm. long, some- what shorter than its stipe: pods at maturity filiform, 4-6 cm. long or possibly more, irregularly curved and spreading, on stipes nearly half as long and somewhat longer than the pedicels. This is a tentative description of a seemingly excellent species, and is described from only a fragment of the plant. This had been gathered for a bouquet by Mrs. Crourners, on a dry hillside, near Big Willow post-office, in Canyon Co., Idaho, about May 25, 1910, where it undoubtedly is indigenous. Igrt] NELSON—IDAHO PLANTS 263 This fragment is no. 217 in MACBRIDE’s series. He will try to secure the plant in quantity in rort. Thelypodium milleflorum, n. sp.—Tall, branching, wholly glabrous, biennial, 1-2 m. high, the stout main axis and the much slenderer ascending branches a deep purple below, becoming paler upward: leaves coarsely and irregularly dentate to entire, passing from oblong below to linear above; the lower petioles 6~r15 cm. long, usually shorter than the blades, becoming shorter upward: inflorescence greatly crowded, at length very long (that of the main axis often 4-6 dm.) but even in fruit quite dense: flowers, pedicels, and even the rachis very pale or milky white: sepals narrowly oblong-linear, slightly cucullate and greenish at the tip, about 5 mm. long: petals very narrow, twice as long as the sepals; the spreading blade nearly linear: the clawlike portion filiform but distinctly expanding again near the base: filaments at length well exserted, and the purple, linear, scarcely sagittate anthers coiled: pods a pure green, in good contrast with the pale pedicels and rachis, almost filiform, 6-10 cm. long, normally strongly ascending or suberect, but often irregularly spreading as if from their weight: stipe 2-3 mm. long; the style about the same length: the ascending pedicels a little longer than the stipes. This is T. Jaciniatum Endl. in part, some specimens being found in herbaria under that name. That species differs from this in many ways, but notice- ably its shabitat (on rocks), its smaller size, its laciniate leaves, its shorter, thicker, spreading pods, and opener inflorescence with green pedicels and rachis. The best specimens are MACBRIDE 234, New Plymouth, Idaho; abundant in rich soils on open slopes; in May, and by June in full fruit. It is also rep- resented by Cusick 1955, from dry bottom lands, Malheur Co., Oregon; AKER 1020, Eagle Valley, Ormsby Co., Nevada; CorTon 391, Yakima region, Washington. Rorrpa patusrris (L.) Bess.—In studying MAcBRIDE’s col- lections, I found a variation of this widely dispersed species that is quite noteworthy. This led to an examination of all the available Specimens at hand, as well as of those representing what we have been calling R. hispida (Desv.) Brit. In this study it became evident that MAcBRIDE’s specimens have the size, habit, and general aspect, and the perfect glabrateness of R. palustris, but - 264 BOTANICAL GAZETTE [OCTOBER the globose or subglobose pods of R. hispida. One is therefore driven to the conclusion that these are but variations of one species. In the present disturbed condition of nomenclature, one scarcely knows what generic designation to employ. However, if one ignores names prior to 1753, the order of the three names commonly employed seems to be Roripa Scop., Fl. Carn. 520. 1760; Radicula Dell. ex Moench, Meth. 262. 1794; Nasturtium R. Br. Ait., Hort. Kew. Ed. 2. 4:109. 1812. Following the same plan on the specific name it seems to result — as follows: Roripa terrestris (R. Br.), n. comb.—Nasturtium terrestre R. Br., l.c.; N. palustre DC., Syst. 2:191. 1821; Roripa palustris (L.) Bess., Enum. 27. 1821. RORIPA TERRESTRIS hispida, n. comb.—Brachylobus hispidus Desv., Journ. Bot. 3:183. 1814; Nasturtium hispidum DC., L.c.; Roripa palustris hispida Rybd., Contrib. U.S. Nat. Herb. 3:149. 1895. RoRIPA TERRISTRIS globosa, n. var.—Tall and often declined, 4-10 dm. high, perfectly glabrous; pods globose or subglobose, with a short necklike constriction between pod and receptacle. MACBRIDE 275 is typical; swampy land, Falk’s Store, Canyon Co., Idaho, June 22, 1910; also by AVEN Netson, Head of Wood’s Creek, Albany Co., Wyoming, August 1910. Spiraea idahoensis, n.sp.—A shrub, wholly glabrous throughout, 10-18 dm. high, branched below; the current year’s branches erect, 3-5 dm. long and very leafy: bark of young branches very pale reddish brown: leaves large, ovate to elliptic or often oval, usually rounded-obtuse at both ends but sometimes subacute at apex, nearly regularly serrate often almost to the base, 5-9 cm. long: panicle large, more or less compound, cylindrical or pyramidal, ' the lower branches of the panicle axillary to the uppermost some- what reduced leaves: calyx lobes reflexed, triangular-ovate, mostly acute, about as long as the disk: petals rose color, about 2 mm. long, twice as long as the calyx lobes, ovate, subacute or obtuse: filaments slender, more than twice as long as the petals: carpels ovate-oblong, smooth and polished, about o. 5 m. long. It is singular that this Idaho shrub should so long have passed for S. Wenziesii Hook. That species finds its typical development along streams and 1g11] NELSON—IDAHO PLANTS : 265 in cold bogs of the Northwest. It is always more or less pubescent, and its leaves are typically narrower and smaller. Its Idaho counterpart is a shrub of the mountains or foothills, in moist soil but not in marshy or wet places. S. idahoensis is reported plentiful throughout southern Idaho. The type is MACBRIDE 630, collected at Trinity, Elmore Co., August 23, IgIo. Potentilla trina, n. sp.—Perennial from a rough shreddy but slender vertical caudek, 4-8 cm. long, green and glabrate or even quite glabrous: stems less than 1 dm. high, slender but erect, few- leaved and few-flowered: leaves trifoliate: basal leaves on slender petioles 5-8 cm. long; leaflets short-petioled or subsessile, 1-3 cm. long, broadly obovate-cuneate, deeply and incisely toothed, the teeth more or less incised; stem leaves sessile, narrowly cuneate, incisely toothed at apex: cymes very few-flowered: calyx tube sparsely and minutely hirsute; sepals triangular-lanceolate, about 5mm. long, acute, obscurely ciliolate; bractlets oblong, mostly obtuse, shorter than the sepals: petals obovate, emarginate, 6-8 mm. long: stamens about 20: carpels 20-25. his is a very near relative of P. emarginata Pursh, and may be only a 8eographical variety of that arctic species. If it stands as a species, it must do So on the strength of its almost glabrate condition, larger and longer rootstocks, larger leaflets, and erect habit. Collected by Macsrine in the Trinity Mountains, on the grassy banks of Star Lake, one of the Trinity Lakes, August 30, 1910, no. 680. Only a few plants were found. Prunus padifolia, n. comb.—Cerasus padifolia Greene, Proc. Biol. Soc. Wash. 18: 59. 1905. MAcBRIDE secured some excellent red cherry specimens on his collect- ing trip in Idaho in 1910. These led to an examination of GREENE’s interest- ing paper on “Some West American red cherries.” A checking up of the Specimens in the Rocky Mountain Herbarium in the light of this paper revealed Some sheets referable to the above name, including MACBRIDE 443 and 479 from Silver City and Twilight Gulch. He secured two sets of specimens, one typically red-fruited, the other with fruit a clear lemon yellow. Otherwise no differences in the two collections could be seen. A character not mentioned y GREENE is the glandular denticulation of the leaf margin. Thermopsis xylorhiza, n. sp.—Stems clustered, erect, rather Slender, from a branched woody caudex surmounting a stout Woody root, 4~7 dm. high, simple and (at maturity) leafless below, sparingly branched above, glabrate and somewhat striate: green, 266 BOTANICAL GAZETTE [OCTOBER glabrous above, very sparsely pubescent beneath; the stipules - ovate or obovate, obtuse or acutish, 2-4 cm. long, either longer or shorter than the petiole; leaflets oval to narrowly elliptic, obtuse or acutish at apex, mostly somewhat cuneate at base, 4-8 cm. long: raceme of 10-20 rather crowded flowers; calyx finely pubes- cent;' the campanulate tube 6-7 mm. long, the triangular acute teeth half as long; the deep-yellow corolla more than twice as long as the calyx: the young pods erect, straight, white with fine silky pubescence, at maturity greenish and sparingly pubescent, moder- ately or only slightly arcuate, spreading, 4-8 cm. long and 5-7 mm. broad; the pedicels 5 mm. or less. So far as known to the writer, the other western species all have a semi- fleshy running rootstock, but aside from the woody character of the caudex and roots this species has other good characters to distinguish it. Secured by MacsriveE at Falk’s Store, Canyon Co., Idaho, May 24, 1919, no. go. Hypericum tapetoides, n. sp.—Depressed perennial, spreading by the slender rhizome-like stems which root at the nodes, very leafy: leaves glabrous, oval or obovate, tapering to the half- clasping base, 5 mm. or less long, longer than the internodes: flowers rarely solitary terminal, usually in cymes of 3-several: sepals 5, similar, narrowly elliptic-oblong, abruptly acute, about 3 mm. long: petals 5, orange yellow, elliptic, very delicate, 5—7-nerved, as long as or longer than the sepals, marcescent: stamens 12-20, distinct, nearly as long as the petals: styles 2-4, equaling the stamens, slightly dilated upward to the truncate or subcapitate summit: capsule ovoid, acute, as long as the sepals: seeds numer- ous, oblong, minutely longitudinally roughened striate. Very distinct from H. bryophytum Elmer, Bor. Gaz. 36:60. 1903, and from H. anagalloides nevadense Greene, Fl. Fran. 113, apparently the only species to which it makes a close approach. It was found growing in dense mats on sunny mossy, boggy stream and lake banks, usually intermingled with mosses and with these forming thick soppy-wet carpets of green. MACBRIDE 453, Silver City, Owyhee Mountains, in bloom, July 22; no. 570, Trinity, Elmore Co., in fruit, August 1910. SPHAERALCEA RIVULARIS diversa, n. var.—Differing from the species in the green and almost glabrous leaves which are shallowly only 3-5-lobed; the lobes mostly obtuse, often broadly rounded, 1911] NELSON—IDAHO PLANTS 267 never sharply serrate on the margin but varying from entire to merely undulate crenate: flowers not crowded-terminal as in the species, but axillary-pediceled in the upper leaves and in a short nearly naked terminal raceme of 3 or 4 flowers: carpels hirsute- hispid on upper part of the back only. MACBRIDE 582, moist hillsides, Manyon Creek, Elmore Co., August 11, IgIo. Phaeostoma rhomboidea, n. comb.—Clarkia rhomboidea Dougl., Hook. Fl. Bor. Am. 1:214. 1833; Opsianthes gaurioides Lilja, Linnaea 15:261. 1840. The genus Phaeostoma was established by Spacu (Hist. Veg. Phan. 4: 392. 1835), one species being referred to it, namely P. Douglasii, which was the earlier Clarkia elegans Dougl. I am not so much surprised that this excellent genus was later suppressed (during the Benthamian era) as I am that it has not been since restored. There are only a very few species referable to it, but these are so aberrant in the genus Clarkia that one trying to find them by means of keys now available meets with a number of contradictory and mis- leading statements. Clarkia rhomboidea runs just as readily to Godetia as to Clarkia, for it requires a decided mental bias to recognize the narrowed base of its petals as a claw. Removing the species with entire petals from Clarkia, it becomes homo- geneous in that all the species have clawed, 3-lobed petals, only 4 real stamens, and a stigma evidently lobed. Phaeostoma, on the other hand, has entire _ petals with or without claw, eight perfect subequal stamens, and a stigma with lobes so short that the stigma looks capitate or disciform. It is to be noted too that in Phaeostoma some of the leaves are opposite. The other species referable to this genus are as follows: Phaeostoma elegans, n. comb.—Clarkia elegans Dougl., Lindl. Bot. Reg. t. 1575. _ Phaeostoma xanthiana, n. comb.—Clarkia xanthiana Gray, Proc. Bost. Soc. Nat. Hist. 72145. 1861. Phaeostoma parviflora, n. comb.—Clarkia parviflora Eastwood, Bull. Torr. Ctub 30:492. 1903. Sphaerostigma implexa, n. sp.—Annual, more or less branched from the base and upward, 1-2 dm. high; the stems and branches puberulent and purplish tinged, the bark not exfoliating; the branches ascending, almost as long as the main axis: leaves glabrate or puberulent, oblanceolate to oblong-lanceolate, tapering to a short petiole; the lower 5-7 cm. long, upward passing into the 268 BOTANICAL GAZETTE [OCTOBER narrow bracts which are gradually reduced; raceme crowded, becoming narrow and more or less secund, puberulent: calyx lobes lanceolate, 5-6mm. long, and about twice as long as the tube: petals greenish- or yellowish-white, suborbicular, abruptly acutish, or with a tooth on the subtruncate apex, as long as the calyx lobes: capsule narrowly linear, subcylindrical and only slightly enlarged downward, at maturity 20-25 mm. long and greatly con- torted or implexed. The habit and general appearance of this suggests S. decorticans (H. & A.) Small, from which it is far removed geographically and otherwise. ype, MacsripE 27, from Falk’s Store, Canyon Co., Idaho, dry stony hill- sides, May 17, 1910. Onagra (OrNoTHERA) ornata, n. sp.—Stout biennial, widely spreading from the summit of a rather large woody root; the sev- eral stems assurgent and simple, 5 dm. or more high, very leafy, densely and finely pubescent, with some scattering ciliate hairs: leaves narrowly oblong-lanceolate to linear-lanceloate, the largest 10-14 cm. long, reduced toward the base and into the bracts (first year leaves not seen), with short dense subcinerous pubescence: inflorescence crowded: calyx densely white hirsute-pubescent, at anthesis its tube less than 4 cm. long, about twice as long as the ovary, its lobes as long as or longer than the tube: corolla a deep golden yellow, unchanged in drying or shading to orange; the petals broadly triangular-obovate or obcordate, as long as the calyx lobes: anthers yellow, 12-15 mm. long; the filaments much | shorter than the petals: style not protruding from the bud but elongating and surpassing the stamens as the buds open: capsule pubescent, 2-3 cm. long, somewhat thickened on the angles and only slightly tapering: seeds angled. This highly beautiful evening’ primrose, coming as it does from a state supposedly fairly well worked, is a distinct surprise. Doubtless, however, it is an indigenous plant. The excellent key prepared by Dr. R. R GaTES (Mo. Bot. Gar. Rept. 20:126. 1909) now makes it possible at least to place species of this genus in fairly well-marked groups. This proposed specie? will be somewhat aberrant in the O. grandiflora group. That the present species has nothing in common with the O. biennis group is evident not only from GarTEs’s key, but is attested by the well-known fact that in that group the petals of all the recognized western species (O. strigosa, O. Hookeri, etc-) become 1git] NELSON—IDAHO PLANTS 269 paler, pinkish or even white, on drying. GREENE is the only writer who has mentioned a western form (California) in which the petals remain yellow, or turn a deeper yellow, but he referred this to the misunderstood Oenothera grandiflora Ait., which Miss Vatt (Torreya 5:9. 1905) has since definitely located for us. It seems strange, however, that neither HowELL nor PIPER make any mention in their floras of the large-flowered species representes by this and the next. MacsrivE reports this species as scattering in the foothills but more abun- dant upon the adjacent mountain slopes, near Boise, Idaho; no. 262, June 18, IgIo. Onagra (OENOTHERA) Macbrideae, n. sp.—Annual, from a rather slender, vertical taproot: stem simple below or sometimes with one or two smaller accessory erect stems from the crown, usually sparingly branched above, 4-8 dm. high, glabrate in appear- ance but with a sparse crisped pubescence and a few longer cilia- tions: leaves glabrate or more evidently pubescent, especially on the midrib or veins which are often substrigose; the radical leaves narrowly oblanceolate, tapering above to the acute apex; cauline leaves similar but smaller and passing into the sessile bracts: inflorescence open from the first: calyx lobes nearly glabrous, about 3cm. long, shorter than the glabrous slender tube, the linear tips short: petals yellow, thin, fading to a deeper yellow or orange red, obovate-obcordate, about 4 cm. long, twice as long as the filaments: anthers more than 1 cm. long: pistil not protruding from the bud, about equaling the petals: capsule moderately fusiform, nearly straight, and 8-costate, 2-3 cm. long: seeds apparently wing-angled. Two such splendid plants as these by one collector, seem quite an achieve- ment for one season. In so limited a genus, since both are from the same State, one might suspect that they should be united, but that is impossible, for one is a coarse, pubescent, spreading biennial with woody stems and crowded inflorescence: the other a glabrate, erect, herbaceous annual with few and much larger flowers. That this species is indigenous can scarcely be doubted, It was secured more than 50 miles from a railroad in a practically uninhabited desert area in the Owyhee Mountains, Idaho. It affords me much pleasure to dedicate it to Mrs. C. M. Macarme, who so industriously and discriminatingly assisted her son in the field work during most of the season of 1910. Type no. 473, Twilight Gulch, July 27, rg10. Dodecatheon dispar, n. sp.—Glabrous throughout, obscurely, if at all, granular-glandular in the inflorescence: rootstock short, thick, 270 BOTANICAL GAZETTE [OCTOBER ascending or erect, producing an abundance of fleshy roots: leaves numerous, oblanceolate, tapering gradually into the long, margined base, tapering lanceolately toward the subacute apex also, 2-3 dm. long: scapes 4-6 dm. high, few-flowered (1-6), the pedicels very unequal: calyx tube obconical, about 5 mm. long; calyx lobes linear- lanceolate, longer than the tube: the sinuses broadly rounded: corolla lobes lance-linear, one-half longer than the sepals, the tube very short: stamens distinct and sessile, stout subulate, as long as the sepals: capsule circumscissile near the apex, then splitting at the summit only into 5 valves, each of which opens for a shorter distance in the dorsal suture, ovoid to oblong, equaling the calyx lobes. Among the operculate species, having distinct anthers, I can find none with which to compare this large glabrous form. MACBRIDE 672, moist flats near the Trinity Lakes, Elmore Co., Idaho, August 29, 1g10. COLLOMIA GRANDIFLORA axillaris, n. var.—Stems slender, cin- erous-puberulent, 3-5 dm. high: leaves puberulent: the capitate flower clusters small and few-flowered, on very short foliar-bracted branchlets axillary in most or even all of the leaves, the terminal cluster often not much larger than the others: calyx very glandular. Collomia grandiflora is thus seen to be exceedingly variable. Any one com- paring this variety with material typical of the species would have no hesitation in declaring them remarkably distinct. But with C. grandiflora diffusa Mul- ford before you, and a goodly number of intermediates between the species and the varieties, one hesitates to name it at all, So striking a variation, how- ever, ought to be designated in some way. MACBRIDE 580 is the type; Trinity, Elmore Co., August 8, rgro, open hill- sides. Less well represented by his no. 376, Silver City, July 14, 1910, steep hillsides. Phlox aculeata, n. sp.—Depressed-caespitose on the intricately slender-branched caudex: stems slender, sparsely crisped, viscid- pubescent, especially above, the internodes short or nearly wanting: leaves densely crowded, filiform, straight or curved, rather rigid and aculeate, the midrib and margins slightly thickened, obscurely puberulent and the uppermost also minutely glandular; usually only 10-12 mm. long but often a few of them are a half longer: flowers solitary or more often 3-5 at the ends of the branchlets, on pedicels 3-7 mm. long: calyx densely glandular-pubescent, 1911] NELSON—IDAHO PLANTS 271 apparently cleft nearly to the base: its lobes nearly linear, scarious on the slightly broadened base, acuminate and aculeate above, 7-8 mm. long: corolla usually a deep pink, shading to lighter or even white; its tube a half longer than the calyx; its lobes narrowly ovate, rounded and obscurely denticulate at summit, about 8 mm. long: style and the longer stamens as long as the corolla tube: capsule large, spreading the calyx lobes apart, 4-5 mm. long: seeds oblong-ovate, rugulose and minutely puncticulate. It might be referred to the P. caespitosa group but for the usually 3-5- flowered cymes which relate it to the Kelseyi group (5 species), and of these it is most nearly related to P. pinifolia Brand., which is erect and with calyx and pedicels pilose and not glandular. Macsripe tells me this is common on the dry bench lands in the vicinity of New Plymouth, in the Payette Valley. His collection, no. 73, New Plymouth, May 20, 1910, supplies the type. Phacelia luteopurpurea, n. sp.—Slender annual, sparingly branched from the base and upward, hispidly short-hirsute, 1-2 dm. high: leaves 2-5 cm. long, somewhat irregularly bipinnate, the oblong-linear lobes rarely few-toothed: inflorescence rather densely and conspicuously dark glandular-pubescent: sepals linear, spatulate, as long as the corolla tube and exceeding the Mature capsule, hispid as well as glandular: corolla narrowly campanulate; the tube yellow or yellowish, only 3-4 mm. long, more than twice as long as the broadly rounded spreading purple lobes: stamens nearly as long as the corolla tube, inserted in the Margin of pocket-like depressions near the base but without any vertical folds: style 2-cleft at apex only: capsule ellipsoidal, 2mm. or more long; the ovules about 16; the seeds often fewer, irregularly oblong, with fine transverse acute rugulae. Most nearly related to P. bicolor Torr., but at once distinguished by its glandular pubescence and short corolla. "These two, with P. glandulifera Piper, P. Ivesiana Torr., and P. Fremontii, are the members of the section Evctypta Wats. (Micnoomnerns A. DC.). The type is MacsripE 84, New Plymouth, Idaho, May 21, 1910; sandy soil, Madronella purpurea (Howell), n. comb.—Monardella purpurea Howell, Fl. N.W. Am. 550.—Low, scarcely more than 2 dm. high, the shrubby hase freely branched: twigs of the season very numer- 252 BOTANICAL GAZETTE [OCTOBER ous, slender, simple, puberulent, 10-18 cm. high, very leafy: leaves entire, oblong or ovate-lanceolate, subacute, rather thick, obscurely puberulent or nearly glabrous, 12-25 mm. long, usually much exceeding the internodes, tapering into a short petiole: head of flowers close, 15-20 mm. high and about as broad; involucral bracts in two rows, the outer only slightly shorter, all obovate: calyx tube about 1o mm. long, minutely hirsute; the small tri- angular teeth softly hirsute: corolla tube minutely pubescent, distinctly exceeding the calyx, its linear purple lobes about half as long as the tube. GREENE’s argument (Leaflets 1:168) for discarding the name Monardella seems convincing; therefore, I transfer two most excellent species. The above is re-characterized in the light of Macsripe’s perfect specimens from Silver City, in the Owyhee Mountains, no. 434, growing in granite soils. Madronella parvifolia (Greene), n. comb.—Monardella parvi- folia Greene, Pl. Baker. 3:22. 1901; appearing in CouLTER and Netson’s Manual as Monardella parviflora, a slip in copying. LITHOSPERUM RUDERALE lanceolatum, n. comb.—L. lanceolatum Rydb., Mem. N.Y. Bot. Gard. 1: 233. 1900. There can be little doubt that Prrer is right (Contrib. U.S. Nat. Herb. 11:486. 1906) in replacing L. pilosum Nutt. by L. ruderale Dougl.; but not in reducing L. lanceolatum to complete synonomy. RYyDBERG’s name probably should be retained as representing a recognizable variety. The characters on which he relied to separate it specifically from its nearest ally, L. pilosum, are characters of degree, mainly size. This character may so readily be ac- counted for by environment that one is not justified in giving more than varietal significance to it. In the light of most remarkable specimens of this variety secured by MAcBRIDE at Big Willow, Canyon Co., no. 110, the salient char- acters may be restated as follows: Stems very numerous, stout 4-6dm. high: the inflorescence paniculately branched, sepals elongating and surpassing the very large nutlets, which are distinctly keeled and provided with a conspicuous flaring white polished collar bordering the broad con- cave basal scar. Pentstemon Macbridei, n. sp.—Caudex woody, subterranean: stems several to many from each of the few crowns of the caudex, puberulent, slender, simple, erect, closely and equably leafy, 1-3 dm. long exclusive of the ample inflorescence: leaves puberu- Foti] NELSON—IDAHO PLANTS 273 lent, narrowly linear, tapering to both ends, 3-6 cm. long, all sessile except the lowest which are somewhat reduced in size and short-petioled, the upper passing into the bracts which are gradually reduced upward: the cymose panicle ample, 1-2 dm. long, or often longer, the open, lower branchlets more or less elongated and bear- ing simple or compound cymes, puberulent as are also the pedicels ~ which are often much longer than the calyx and with a small pair of bractlets: sepals broadly ovate-lanceolate, acute, green and glabrate with subscarious margin, 5-6 mm. long: corolla showy, bluish-purple, gradually dilated, moderately bilabiate, glabrous within and without, its tube 14-16 mm. long, its oval-oblong lobes spreading, about 5 mm. long: anthers saccate, opening only above the middle, glabrous even on the line of dehiscence, sterile filament flattened at apex, wholly glabrous. This beautiful Pentstemon seems not to be closely related to any de- scribed species except P. gracilenta Gray, from which it is readily distinguished. That has glabrous herbage and is glandular pubescent in the inflorescence. Its leaves are broader and largely basal, upwardly becoming distant and reduced; the relatively smaller and narrower inflorescence is naked-peduncu- late; and the corolla is smaller and the sterile filament more or less bearded. I take pleasure in naming this for my young friend J. FRANCIS MACBRIDE, who collected so industriously during the summer of 1910. The type is no 105, secured on loamy slopes, near Big Willow, Canyon Co., Idaho, May 27. Pentstemon perpulcher, n. sp.—Stems few-several from a short thick woody caudex, 4-8dm. high including the inflorescence, erect or ascending, puberulent below, becoming glabrous above: basal leaves narrowly oblanceolate, 3-10 cm. long. including the tapering base and petiole; cauline linear-lanceolate, with sessile clasping base, reduced upward and passing into the linear bracts: thyrsus crowded or more open, rather narrow and secund, 1-3 dm. long: sepals glabrous, ovate, acute with subscarious and minutely €rose margins: corolla blue, mostly less than 20 mm. long, with moderately dilated glal throat and oval lobes: anthers dehiscent, glabrous; sterile filament stiffly bearded at the tip, not at all dilated. I hesitate to designate another species in the P. glaber group. Several Segregates have already been published by various authors, none of which, however, seems to have anything to do with the specimens in hand. The 274 BOTANICAL GAZETTE [OCTOBER characters relied upon to separate the new species are (a) the erect slender stems with the narrow leaves and secund thyrse, giving the plant the aspect of P. unilateralis Rydb.; (6) the pronounced puberulence of the plant below the inflorescence; (c) the short corolla, a third shorter than any of the other species of the P. glaber group; (d) the glabrous anthers; (¢) the habitat, the plant seemingly much at home on dry banks of ‘the sage brush deserts of western Idaho. All of these characters are directly opposed to the accepted ones of typical P. glaber Pursh. MacsrIpE 80, New Plymouth, Canyon Co., Idaho, May 21, roo, is the type. Pentstemon Woodsii, n. sp.—Moderately short pubescent throughout, and more or less glandular upward: stems wholly herbaceous, from the branches of a short woody subterranean caudex, erect, leafy, terminating in a small cyme of three or five flowers: leaves not at all coriaceous, oblong to oblong-lanceolate, acute, ascending, dentate or denticulate except the lower which are smaller than the others and entire, the larger 3 dm. or more in length and much longer than the internodes: sepals narrowly lanceolate, about 1omm. long: corolla purplish blue, gradually dilated upward, about 3 cm. long, its oval-oblong lobes less than 5m. long, finely woolly in the throat on the lower lip: anthers dehiscent through the junction of the two cells but not explanate, finely matted-woolly; sterile filament not dilated at apex, the very tip bearing a few long woolly hairs: style slender, scarcely exserted but surpassing the included stamens. I would refer the present specimens to P. montanus Greene (of which I have seen no authentic specimens) were it not that GREENE says of that “leaves cinerously puberulent, corolla pink-purple, and sterile filament naked.” He would hardly have failed to mention the decidedly glandular pubescence of the inflorescence and the thin, not at all leathery, leaves. In TWEEDY ’S specimens, cited as the type, it is mentioned that the corollas ackent in drying, which is not the case at all in P. Woodsii. The fine specimens taken as the type were received from Mr. C. N. Woops, Supervisor of the Sawtooth Forest Reserve, no. 26 5, for whom it is a pleasure to name the species. UNIVERSITY OF WYoMING LARAMIE, WYOMING THE DEVELOPMENT OF THE ASCOCARP OF LACHNEA SCUTELLATA? WILLIAM H. Brown (WITH PLATE IX AND FIFTY-ONE FIGURES) The material upon which the present study is based was col- lected at Cold Spring Harbor, Long Island, where the ascocarps of Lachnea were found in large numbers upon decaying wood in damp places. The ascocarps appear to be frequently produced in crops, as a considerable number of about the same age are often found on a single log. If all of these are removed while still young, a second crop will usually appear in a few days. If now the young ascocarps are removed as they appear, successive crops may con- tinue to be produced for some time. By this means a large number of young stages can be quite easily obtained. For microscopical study, sections were cut 3-5 # thick and stained with Flemming’s triple or Haidenhain’s iron-alum hema- toxylin. The latter gave the best results. Lachnea scutellata has a disk-shaped ascocarp, 2 mm.—1 cm. in diameter, the upper surface of which is covered by the hymenium, Which is colored red. The margin and lower surface of the disk are brown and thickly beset with long brown setae. The setae are long, septate hyphae, the outer walls of which are greatly thickened. A cross-section of an ascocarp (plate fig. 1) shows that the inside is composed of densely interlacing hyphae, while the margin and lower Surface are covered by a parenchymatous cortical layer consisting of large, thick-walled hyphae which run nearly parallel to each other and perpendicular to the outer surface of the ascocarp. Woronin (38) described the ascocarp of Lachnea scutellata as originating in the production of an archicarp, which soon became surrounded by vegetative hyphae that obscured its further develop- ment. * Contribution from the Botanical Laboratory of the Johns Hopkins University, Oo. —. 275) [Botanical Gazette, vol. 52 276 BOTANICAL GAZETTE [OCTOBER In the youngest specimens obtained, the archicarp consisted of a row of 7-9 cells, which had just become surrounded by vegetative hyphae. The ascogonium is the penultimate cell of the archi- carp, which when mature consists of about 9 cells (plate fig. 3). The ascogonium and all of the vegetative cells are multinucleate. In the youngest specimens the ascogonium was about one-third to one-fourth its size at maturity. There was observed neither at this time nor later any sign of an antheridium, and since in the young specimens the ascocarp consisted of only a few hyphae, it should have been plainly visible even if degenerated. It seems probable, therefore, that no antheridium is present. Before the ascogonium reaches its mature size, the walls of the vegetative hyphae on the outside of the young ascocarp become thickened, and these hyphae form the outer covering of the asco- carp (plate fig. 2). This covering undergoes no further growth, but remains at the base of the mature ascocarp and forms the first part of the cortex. The hyphae around the ascogonium remain active and give rise, over the ascogonium, to small hyphae which | grow out to form paraphyses (plate fig. 3). The same hyphae which give rise to the hyphae producing the paraphyses give off branches, around the region of the paraphyses, some of which grow up and add to the cortex, while others grow out and form setae. As the cells of the setae and cortex reach their mature size, they become greatly vacuolated and the outer walls increase greatly in thickness. When the setae are first formed, they are bent down toward the center of the top of the young ascocarp, and thus form a covering over the developing hymenium (plate fig. 4). When a part of the cortex is once formed, the development of that part ceases, and further additions are made only in the region between the paraphyses and the cortex. The hyphae here remain active and give rise on one side to paraphyses and on the other to setae and more of the cortex of the ascocarp. As this continues, the older setae are carried outward, and finally come to be on the lower surface of the ascocarp. The setae which are formed first are not as long as those which are formed later, so that the setae around the margin of the disk are longer than those on the under surface. As the hymenium increases in diameter, by the production of more tgit] BROW N—LACHNEA SCUTELLATA 297 paraphyses and the pushing in of the ascogenous hyphae, which by this time have grown out from the ascogonium, it becomes too large to be covered by the setae and is thus exposed. When this has occurred, the ascocarp has attained its mature form (plate fig. 1). The relation of the various parts of the ascocarp is shown diagrammatically in fig. r. In this diagram are shown both the ascogonium. and asci, whereas the ascogonium always disappears before the formation of asci. \ es L? £4 () \ VA < } e \ /) va y, 2 2 ey , f A | F | » WY WY | AS ) p T/ ; ff ZZ a \ y WA \ Be =, LIA YY AY 3 iy eS wan SN ( oh YZ | KE oT iy J ENN y |) WU WE, A CO, TTIW Y WW LZ AS : oa ZI] ———— “iS Lo t if a | i ag an oa | , Se Se KNY | r\\ WEED ! ? OSM \Y =o AS }/ = Fic. 1.~—Diagrammatic cross-section of ascocarp The vegetative nuclei usually contain a nucleolus and a small amount of scattered chromatin, but sometimes the chromatin is collected into a rounded mass resembling a nucleolus. In dividing the vegetative nuclei show five chromosomes. The nuclei of Lach- nea contain comparatively little stainable material, as will be seen from the figures. This scarcity of stainable material makes the figures appear diagrammatic. Such is not the case, however, as all figures were drawn with a camera lucida, and in those illus- trating nuclear details, all of the stainable material in the nuclei is 278 BOTANICAL GAZETTE [OCTOBER figured. In most cases the cytoplasm is omitted, as this resembles that usually found in Ascomycetes. The nuclei in the ascogonium resemble the vegetative nuclei Fics. 2-13.—Fig. 2, nucleus of ascogonium in resting stage; fig. 3, formation of chromosomes in nucleus of ascogonium somes are on the nuclear wall, but owing to their position appear to be inside the nucleus; fig. 9, metaphase in nucleus of ascogonium; fig. 10, anaphase in nucleus of ascogonium; fig. tr, telophase in nucleus of ascogonium; fig. 12, reorganization of nuclei in ascogonium; fig. 13, reorganization of nuclei, in contact, in ascogonium, all X 11,200. except that they are somewhat larger. The chromatin is usually scattered throughout the nucleus, but sometimes it is arranged in a definite spireme (fig. 2). This condition probably indicates the approach of division. It has not been possible to determine defi- rott] BROWN—LACHNEA SCUTELLATA 279 nitely whether or not the spireme is continuous. Often several loops are tangled together, so that it is impossible to foHow indi- vidual parts. Still more frequently parts of the spireme run along the nuclear membrane for considerable distances, so that even if it were continuous it could be followed only with considerable diffi- culty. At other times there appear to be definite breaks. This appearance may be due to a failure of the spireme to take the stain or to poor fixation, but there is nothing to indicate that such is the case. The spireme, soon after its formation, appears to contract and divide to form five chromosomes (figs. 3, 4). ‘The chromosomes may be rather widely separated (fig. 4), but frequently they are col- lected together into a compact group resembling a second nucleolus (figs. 5,6). The group can be distinguished, however, from a nucleo- lus by its irregular outlines. This grouping of the chromosomes is not confined to the ascogonium, but can be seen throughout the ascogenous hyphae and in the prophases of the second and third divisions of the ascus. It is probably also the explanation of the grouping of the chromatin seen in the vegetative nuclei. While the chromosomes are being formed, linin fibers make their appearance in the nucleus. At the same time a centrosome appears on the nuclear membrane. This was not visible during the resting condition and appears to arise de novo. The centrosome is not a point, but rather a flattened area, apparently composed of many granules. When the centrosome was first observed, it was already connected with the chromosomes by the linin fibers in the nuclear cavity (fig. 7). Soon after this the centrosome (fig. 8) divides, and the daughter centrosomes move apart and come to be Situated at the opposite poles of the complete spindle (fig. 9). The centrosomes in fig. 8 are against the nuclear membrane, but owing to their position appear in the figure to be within the nucleus. The five chromosomes then divide and five daughter chromosomes Proceed to each of the opposite poles (fig. 10). The nuclear mem- brane now breaks down, and the two groups of chromosomes and the nucleolus, which soon disappears, are left free in the cytoplasm (fig. 11). The two groups of chromosomes are usually separated far enough so that when they reorganize the daughter nuclei are Separated by an appreciable distance (fig. 12). F requently, how- 280 BOTANICAL GAZETTE [ocroBER ever, the daughter nuclei reorganize so close together that after a slight growth they are pressed against each other and resemble fusing nuclei (fig. 13). The spindle fibers are frequently present at this stage, and can be seen connecting the two masses of chro- matin, which are still visible in the daughter nuclei. Frequently the masses of chromatin lie against the nuclear membrane, and the disappearing fibers are entirely outside the nucleus, but at other times the fibers appear to cross the nuclear cavity, as in fig. 13. Frequently the chromatin appears, at first sight, to be in the center of the nucleus, when in reality it is lying against the membrane. This is due, of course, to the fact that the chromatin is at the upper or lower surface of the nucleus as it is viewed from above. Division seems to take place rapidly throughout the growth of the ascogonium and the development of the ascogenous hyphae. The nuclei do not divide simultaneously, as all stages, including resting nuclei, can be found in a single ascogonium. There appear, however, to be periods in which division takes place, followed by others in which all of the nuclei are in the resting condition, for a large number of divisions are frequently found in a single ascogo- nium, while others show only resting nuclei. The same type of division that has just been described and the same number of chromosomes persist throughout the development of the ascogonium and ascogenous hyphae. The nuclei decrease somewhat in size during the growth of the ascogonium, and in the early stages of the development of the ascogenous hyphae, but as the ascogenous hyphae develop further, the nuclei increase in size until they come to be slightly larger than in the young ascogonium. No fusion of nuclei has been observed in the ascogonium or in the ascogenous hyphae except in the tips where two nuclei fuse to form the primary nucleus of the ascus. A number of cases were seen in which two nuclei were pressed against each other, but in all of these the nuclear membrane was intact between the nuclei, and the appearance seemed to be due to the fact that the nuclei, _ after division, had reorganized close together, in the manner pre- viously described. It may be said that a fusion of the nuclei would be hard to find, but they have been looked for very carefully ina large number of well fixed and stained preparations. The slight rgtt] BROW N—LACHNEA SCUTELLATA 281 decrease in the size of the nuclei during the development of the asco- carp and the persistence of the same number of chromosomes throughout the ascogonium and ascogenous hyphae, moreover, indicate very strongly that a fusion of nuclei during this stage is not to be expected. When the ascogonium has reached its mature size, it gives off a number of large ascogenous hyphae which are multinucleate from the first (plate fig. 3). The nuclei do not appear to be arranged in pairs or in any other definite manner, but to be scattered irregularly in the hyphae (fig. 14). They are undergoing divi- sion rather rapidly, as has been previously described. About this time the cyto- plasm and nuclei of the other cells of the archicarp begin to degenerate. These cells apparently do not fuse together as in Ascophanus carneus (CUTTING 7). The ascogenous hyphae grow up among the vegetative hyphae which are situated Fics. 14-16.—Fig. 14, outgrowth of ascoge over the ascogonium and _ nous hyphae from ascogonium; fig. 15, storage have been mentioned as ‘lls giving off paraphyses; fig. 16, tips of aE ‘ ascogenous hyphae in hymenium; all X 525. giving rise to paraphyses. As the ascogenous hyphae increase in length, they branch freely and become divided up into a number of large multinucleate cells. Some nuclei are left in the ascogonium and these finally degenerate. When the ascogenous hyphae are growing out from the ascogonium, the vegetative cells over the ascogonium (plate fig. 3) are slender, densely protoplasmic, and extend upward toward the covering of the ascocarp. They thus have the appearance of young paraphyses, but do not take part in the formation of the hymenium until they have developed further. As they grow up they branch freely and 282 BOTANICAL GAZETTE [OCTOBER become thicker and less densely protoplasmic. As the developing ascogenous hyphae grow up and branch among these vegetative hyphae, the older parts of the vegetative hyphae cease to have the appearance of paraphyses, while the younger parts still form a layer ahead of the ascogenous hyphae. When the place where the hymenium is to be formed is finally reached, the layer of paraphyses is thus already completely developed (plate fig. 4). The continued upward growth and branching of the vegetative and ascogenous _ hyphae causes the hymenium to have a much greater diameter than it would have had if it had been formed before the branching had taken place. Some of the vegetative hyphae in the sub- hymenial layer give off branches which form large, densely staining storage cells. These in turn give rise to more paraphyses (fig. 15). In a few cases nuclei in these storage cells have been seen to be fusing, and since in some cases the fusing nuclei are exceptionally large, it may be that nuclei which have been formed by fusion may themselves fuse. The fusion of nuclei in the storage cells is of regular occurrence in Leotia (BROWN 6), but is probably excep- tional in Lachnea scutellata, as most of the nuclei in the storage cells of this species are small and of nearly uniform siz While the storage cells are being formed in the cabh eral layer, the ascogenous hyphae can be seen, in the same region, as rows of large multinucleate cells. These give off smaller multi- nucleate branches which extend upward into the lower part of the hymenium (fig. 16). It is from these branches that the asci are to be formed. The tips of these branches frequently contain two nuclei, and it seems probable that these are cut off together in a single cell, as no such uninucleate cells have been observed in the hymenium or subhymenial layer, although binucleate cells are of frequent occurrence. It is, of course, still possible that uninucleate cells may sometimes be cut off, and that these may have been over- looked, as the uninucleate condition would probably last only a short time. The cutting off of two nuclei in the tip of an ascoge- nous hypha has been described by McCuppin (28) in Helvella elastica. ‘The cutting off of two nuclei or a single one, which subse- quently divided, in Lachnea scutellata would probably not have any effect on the further development, since, as has already been Igt1] BROW N—LACHNEA SCUTELLATA 283 described, the nuclei undergo division in the ascogenous hyphae, so that the two nuclei which are in the tip of a hypha are probably closely related. There appears, moreover, as has been previously pointed out (BRowN 6), to be no reason for thinking that the rela- tion of fusing nuclei can make any difference, if these are all in the same plant and are derived from a single nucleus, with the haploid number of chromosomes. The nuclei in those cells of the ascogenous hyphae which are below the hymenium finally degenerate. In doing so they often swell up to several times their original size, after which the nuclear membrane gradually disappears. This process is quite similar to that described by HARPER (22) for the nuclei in the trichogyne of Pyronema confluens. Before degenerating two or three of the nuclei sometimes fuse togethér. Such fusions are not confined to the nuclei of the ascogenous hyphae, but may occur in other degenerating cells. The binucleate cells previously described as being formed from the ascogenous hyphae grow up in the hymenium and bend over at the tip. The two nuclei pass into the bent portion and divide in the same manner that has been described for the nuclei in the ascogonium (fig. 17). At metaphase there are five chromosomes, and at anaphase five pass to each pole. Walls come in between the daughter nuclei of each pair, thus forming a binucleate penulti- mate and a uninucleate ultimate and antipenultimate cell (fig. 18). This is of course a typical hook. The two nuclei in the penulti- mate cell may fuse to form the nucleus of an ascus (fig. 20), but often they divide and give rise to the nuclei of another hook (fig. 24). The ultimate cell usually grows down and fuses with the stalk (fig. 19), after which the nucleus from the stalk usually migrates into the ultimate cell (fig. 21), although occasionally the nucleus of the ultimate cell may pass into the stalk. After the nucleus of the stalk has migrated into the ultimate cell, it may fuse with the nucleus of the ultimate cell to form the primary nucleus of an — ascus (fig. 22), but usually the two nuclei divide and the ultimate cell grows out to form another hook (figs. 23, 24). Sometimes the nucleus formed by the fusion of the nuclei of the ultimate and ante- Penultimate cells does not develop further. This is usually asso- 284 BOTANICAL GAZETTE [OCTOBER ciated with a vacuolated condition of the cytoplasm. Fig. 25 shows a case in which the penultimate cell has developed into a second hook. The nuclei of the ultimate and antepenultimate cells have fused, but the fusion nucleus has not developed further. The penultimate cell of the second hook has given rise to an ascus, while the nucleus of the ultimate cell has migrated into the ante- penultimate and fused with its nucleus. The processes described above, by which either the ultimate Fics. 17-25.—Fig. 17, tip of ascogenous hyphae, showing form of hook and division of nuclei; fig. 18, binucleate penultimate and uninucleate ultimate and ante- penultimate cells; fig. r9, fusion of nuclei in penultimate cell and fusion of ultimate and antepenultimate cells; fig. 20, fusion nucleus in antepenultimate cell; migration of nucleus from antepenultimate to ultimate cell, followed by outgrowth of ultimate cell; fig. 22, formation of asci from both ultimate and antepenultimate cells; fig. 23, formation of hook from ultimate cell and ascus from penultimate; fig. 24 formation of hooks from both ultimate and penultimate cells; fig. 25, case in which nucleus from antepenultimate cell migrated into ultimate and fused with nucleus of ultimate; a hook was formed from binucleate penultimate cell, the penultimate cell of which in turn gave rise to an ascus, while the nucleus of the ultimate cell migrat into the antepenultimate and fused with its nucleus; all X 1400. Fz + Igtt] BROW N—LACHNEA SCUTELLATA 285 or antepenultimate cell may give rise to a hook, may be repeated many times, so that a large number of asci may be formed finally from a single hypha. Even in young ascocarps, five or six hooks may frequently be seen joined together in various ways, and if it were possible to follow a hypha for a considerable distance, the above number would of course be greatly increased. The significance of these phenomena has been discussed in a previous paper on Leotia and Geoglossum (BROWN 6), in which genera they also occur. As new hooks are successively developed from older ones, that part of the ascogenous hypha which connects the successive hooks, as well as the older parts of the hypha, become vacuolated to such an extent that no cytoplasm can be seen in them. Despite this fact, new hooks and asci are formed quite rapidly. It seems probable, therefore, as HARPER (22) suggests, that the developing asci obtain their nutrient material from the paraphyses, which are in contact with them, by transfusion through the walls. The multiplication of the number of hooks gradually raises the level at which asci are formed. At the same time, the level at which the paraphyses come off is also raised by the formation of new ones from the basal portion of older ones and from storage cells which are being continually formed at a higher level. As growth continues and the hymenium rises higher and higher, the subhymenial layer is increased in height by the addition of the older parts of the hymenium, which are gradually left behind. ile the hymenium is thus being raised, it also increases in diameter. As has already been described, the cells between the hymenium and cortex continually produce new cells which give rise to paraphyses around the margin of the hymenium. At the Same time, hooks formed from the ultimate or penultimate cells of older ones grow in among the paraphyses. Owing to the pro- cesses described above, an ascocarp, after it assumes its mature form, may increase greatly in both height and diameter. When the two nuclei which fuse to form the primary nucleus of the ascus are in the process of fusion, they contain compara- tively little chromatin. This is scattered somewhat irregularly on linin fibers, but shows an approach to the spireme condition 286 BOTANICAL GAZETTE [OCTOBER (fig. 26). The fusion nucleus grows rather rapidly, and as this continues the chromatin soon comes to be arranged in a definite, fine spireme (fig. 27). When this condition has been reached, the spireme does not usually show any free ends, and it can frequently be traced as a continuous thread for considerable distances. It is impossible, however, to follow it through some of the tangles. Frequently threads run to the nuclear membrane or nucleolus, after which it is not possible to trace them further. This suggests that the spireme is not continuous throughout its entire length, but this conclusion must be considered doubtful, as it is difficult to follow a spireme along the nuclear membrane, which is usually irregularly thickened, or to distinguish it from the nucleolus when it is in contact with the latter. While the nucleus is still far from its final size, the spireme shows the approach of synizesis by begin- ning to collect in a tangle either around or to one side of the nucleo- lus (fig. 27). This usually continues until all of the spireme is arranged in a dense tangle in which little detail can be seen (fig. 29). No evidence of a fusion of spiremes during this stage was observed. An examination of figs. 27 and 28 will show that the spireme is not double as it goes into synizesis. The spireme was occasionally seen contracted into a mass about as dense as the nucleolus. This extreme condition may have been due to fixa- tion, but the regular occurrence of synizesis at this stage, and in material in which the fixation seemed to be perfect, certainly seems to indicate that synizesis is, as Mortrrer (29) thinks, a stage in development, and not an artifact due to fixation, as is claimed by SCHAFFNER (32). This view is supported by the fact that the spireme is quite different in appearance before and after synizesis. ynizesis probably lasts for a considerable time, as the nucleus and ascus grow considerably during this period. At the end of synizesis the spireme, which is now much thicker than before, loosens up and becomes spread through the nucleus (figs. 30 and 31). The continuity of the spireme throughout its length at this stage is, just as before synizesis, doubtful. After the spireme has become spread through the nucleus, it splits longi- tudinally (fig. 32). This splitting appears to extend through almost if not quite the entire length of the spireme. The two halves, tgit] BROW N—LACHNEA SCUTELLATA 287 Fics. 26-34. —Fig. 26, fusion of two nucleiin ascus; fig. 27, early stage in approach of synizesis in nucleus of ascus; fig. 28, later stage in approach of synizesis; fig. 29, Synizesis in nucleus of ascus; ie. 30, spireme just after pieerrys fig. 31, spireme spread through nucleus; fig. 32, split spireme; fig. 33, contracted spireme just before formation of chromos osomes; linin fibers — fig. 34, nucleus with five chromo- Somes and well developed fibers; all X28 288 BOTANICAL GAZETTE [OCTOBER however, soon come together again, after which all traces of the split are usually lost, although sometimes evidences of it may be apparent even after the formation of the chromosomes. After the two halves of the spireme have come together, it begins to contract. This contraction continues until the spireme shortens very considerably (fig. 33). The spireme at this stage has the appearance of a continuous thread, the ends of which are probably free. The spireme finally segments into five somewhat elongated chromosomes (fig. 34). Each of these chromosomes is probably bivalent, since the nucleus received five chromosomes from each of the two nuclei which by fusing gave rise to it. The bivalent condition, however, is not indicated by the form of the chromosomes. In this they are probably similar to those of most plants. In Peperomia (Brown 4), however, the two halves appear during the heterotypic prophase, as separate chromosomes con- nected by linin fibers; while in Oenothera (GATES 17) the diploid number of chromosomes appears at the same stage, and in this case some of the chromosomes may not be arranged in pairs. As the spireme contracts, linin fibers appear within the nucleus (fig. 33). Along those fibers, and especially in the early stages, there are small granules which have the appearance of chromatin. They usually stain less densely than the chromatin of the spireme, but frequently they are large and numerous enough to make the fibers along which they are scattered resemble the spireme. It was not possible to tell whether the substance of these granules passed to the chromosomes or took part in the formation of more linin fibers, but since as they disappear the number of linin fibers increases considerably, it seems probable that part of the granules take part in the formation of the fibers. No evidence of the forma- tion of these fibers from the linin of the spireme by the migration of the chromatin has been observed, but since the continuity of the spireme in the early stages is doubtful, and these fibers may resem- ble the spireme very closely, such a possibility, while not probable, can hardly be said to be excluded. It is certain, however, that most of these fibers which will later on take part in the formation of the spindle are formed de novo. As the spindle fibers increase in number, they become connected 1911] BROW N—LACHNEA SCUTELLATA 289 with a centrosome which makes its appearance on the nuclear membrane, and some of them connect the centrosome with the chromosomes (fig. 35). No signs of this centrosome have been visible up to this time, and as there is nothing to indicate that it persists through the resting stages, it is probable that it is formed de novo at each division. In this respect it resembles the centrosphere- like bodies in Polysiphonia violacea (YAMANOUCHI 39), the centro- spheres in. Corallina (Davis 11), and the kinoplasmic caps Oe Fics. 35~41.—Fig. 35, fibers attached to centrosome; fig. 36, nucleus showing extra body which appears much like a chromosome; fig. 37, late prophase of first division in ascus; fig. 38, metaphase of first division; fig. 39, early anaphase of first division; fig: 40, late anaphase, showing division of daughter chromosomes; fig. 41 telophase of first division; all X 2800. in Griffithsia bornetiana (Lewis 25). Deeply staining granules are frequently present in the cytoplasm of Lachnea. These are Particularly abundant around the nucleus at this division. The nuclear membrane does not have an even appearance, but is irregu- larly thick, and often the granules just described are in contact with it. Owing to these facts it has not been possible to trace the origin of the centrosome. The centrosome here, as in the divisions Previously described, is not a spherical body, but a flattened struc- ture composed of a number of granules. 290 BOTANICAL GAZETTE {OCTOBER When the five chromosomes have become connected with the centrosome, other deeply staining bodies are frequently present on the linin fibers. These are usually small and are probably similar to the granules previously described. Sometimes, however, they are as large as or larger than the chromosomes, and may bear such a striking likeness to them that there may appear to be as many as six or seven chromosomes (fig. 36). When the spindle is completely formed, these bodies may still be present on fibers connected with the spindle or nucleolus. Only very small ones, however, have been seen on the spindle, so that when the spindle is formed these bodies, which usually stain lighter than the chromo- somes; can be readily distinguished from them. After the linin fibers have become connected with the cen- trosome, they increase in number. The centrosome then divides, and the two daughter centrosomes take positions at the opposite ends of the spindle (figs. 37 and 38). When the spindle is first formed, it may be at any angle to the longitudinal axis of the ascus, but as division proceeds, it takes a position which is approxi- mately parallel to it. While this is taking place, a set of fibers makes its appearance outside the nucleus. These fibers radiate from the centrosome into the cytoplasm for a considerable distance. At metaphase five chromosomes are present on the spindle (fig. 38). Usually all of these appear to be somewhat elongated and have their longitudinal axis parallel to that of the spindle. Each of the five chromosomes divides transversely, but the divisions do not all take place at the same time, so that as division proceeds, anywhere from six to ten chromosomes may be counted on the spindle. Remembering that when the spireme segmented it gave rise to five elongated chromosomes which were probably bivalent, it would seem that this division probably separates chromosomes which were placed end to end on the spireme and can have nothing to do with the longitudinal split seen in the prophase. There appears to be nothing to indicate that the chromosomes which went into the fusion nucleus have persisted unchanged through the resting nucleus and the prophases of this division, and are the same as the chromosomes which are separated at metaphase. On the contrary, there would seem to have been every chance for an rgit] BROW N—LACHNEA SCUTELLATA 291 exchange of material during synizesis, if not during the resting stage. The independence of unit characters in heredity would seem to favor the view that there may be an exchange of material between chromosomes, for if a given set of unit characters were permanently associated with the same chromosomes, we would expect to find different characters correlated much oftener than they are. If, however, as is generally assumed, the chromosomes are the part of an organism which is responsible for the transmis- sion of hereditary characters, and if different chromosomes are not alike but responsible for different characters, it would be impossible for a promiscuous exchange of material between various chromo- somes to occur without producing chaos. It would seem more likely that the chromosomes are so constituted that only certain kinds of material can be fitted into them, so that while chromosomes derived from different nuclei may exchange material which is responsible for similar sets of characters, they cannot exchange material which is responsible for one kind of character for that responsible for a different kind. The chromosomes at the first division in ie appear to approach the poles rather slowly, as anaphase is very abundant in sections. The ten chromosomes, formed by the division of the five seen at metaphase, are at first grouped at the equator of the spindle and give this stage a striking resemblance to metaphase. Finally, however, they separate into two groups of five, one of which goes to each pole (fig. 39). As the chromosomes approach the poles all of them may again divide (fig. 40). The two halves of a chromosome do not appear to be connected, but when division has just taken place the halves appear to be arranged in pairs, the constituents of which usually lie side by side on the spindle. It would seem from this that this division is due to a longitudinal splitting, and this may be connected with the splitting of the spireme seen in the prophase. a aa alth.’—Henry T. Finck OLIVER DITSON COMPANY 50 Tremont Str CHAS. H. DITSON & 8-10-12 East Seth Street NEW £2, CITY The Country Church and the Rural Problem = KENYON L. BUTTERFIELD resident of the Massachusetts Agricultural College (CUHE aim of President Butterfield’ - ae is to analyze this problem and to inquire = pages 12mo, cloth ~ ipod $1.08 T, * . ° : - University of Chicago Press CACO, PLELNOTS 250 Styles Ask for “Ester- brook’s,” and you get the best pens —easiest writing, longest wearing. Backed bya half- century s reputa- tion. At all stationers. The Esterbrook Steel Pen Mfg. Co. John St., New York Works: Camden, N. J. 26 THE ORIGINAL NON-LEAKABLE FOUNTAIN The easiest pen to fill. One of the features whi:h makes Moore's an unquestionably superior pen is the ease and rapidity with which it can be filled. Simply remove the cap, drop the ink in and the pen is ready for use — no inky pets to unscrew. f © carry around in your ap te or lL. te i doe not afford a she pom = for mae mber also tha fails to wa with my “fiest stroke — peed # son no ae ink flow is always free and even Every silva *s Non-Leakable — — carries with it the most unconditional gu Dealers E deta 168 DEVONSHIR . Bl CANADIAN AGENTS, W.J.GAGE & C0. TORONTO, NSS EXTBOOKS for the graded Sunday school, for religious education in schools and _ colleges, and for individual study of the Bible are published by the University of Chicago Press. They comprise 37 | volumes, providing material for every grade of students, from the kinder- | garten to the college. Put yourself | in touch with the editors, authors, : and publishers of this series and ob- | tain the advice of experts in grading | your Sunday school, or in selecting textbooks for day school, study circle, | | | : or home use. Send for the new handbook of 150 pages, giving specimen pages from all books and much valuable information about graded work in religious education. a The University of Chicago Press Chicago - - Illinois Germ-Laden Dust Spreads Disease. Even with modern systems of ventilation and scrupulous regard for cleanliness, hospitals are ex- posed to germs. When all the usual precautions have been taken es ries Pres a eae o will = sent on aioe oN? 33-37 East 17th Street -<__tccsss«,»«e\«<*9._._ New Fall Books The Baker & Taylor wepienie : te tte se, Concerning Himself Victor L,Whitechureh “The Canonin Res Residence stro’ webbbiogrenn ton novel "which makes the hero a felons en pl ie ape gt r2mo. . 380 pages. Net, $1. Pos Off the Mai ain Roa Victor L. eae hing The story of ‘holarl recluse and - romance which brines: hin ‘taack ite Pee current € I2mo. 320 pages. Net, $1.20. age Io ie e Soundless Tide (F. E. Crichton. * story of Ulster | Pages. Net, $1.20. Wietant ro coe es une The e of Dia Percy Hartley. A sto f love, } pads in the days days of Hen - ry HL ria vps Ars Where the Shininsak Gro Siw gore a. te Jess a 6 Trish romance, rll of Celtic : ease m pniral 2mo. 300 pages. Net, $1.00. FICTION Carey of St. Ursula’s ne Brew Reid. A story of friendships at a Jone boarding school. r2mo. 325 pages. Illustrated yy Sarah Noble aoa Net, $x.20. Postage 10 cents. The Long Green Road Mrs. mf P. McLean Greene. Author of aan Cod Folks.” ‘The record of a rare friendship. 1 att ee Frontispiece. (Net, $1.25. Postage The Third Miss Wenderby Mabel -Grun ce of a quiet but Barnes deeply moving type, with a charming bosga and a pages. Net, happy ending. 12mo. ——— $t.25. Poltagt To cents Ember Light Ro: pats olfe Gilson. The story of a home, the ideals it nourished and those = were sacrificed for Lg B: 7 author of “Katrina.” 12mo0. 35° Illustrated. Net, $1.30. Postsus 12 cents. ; JUVENILE Ms Child’s Guide 2 to the Bible George Hodges, D A sympathetic 1 PE: = ~ =. I2mo. “feats Net, $1.20. Postage ’ A Chile’s s Guide to Living Things pi Sool & ney Brew: An a rece in narrative at oo prose of the familiar fo and processes e. sey Fully rated. Net, § $1.20. Postage * Alice i e in 1 Wonderlan d : Carroll. Illustrated by George Soper. Uni- \ — with Tales from Shakes eare, Renamer 's Heroes, Kingsley's Water Babies. uare 300 pages. With many illustrations in color and lin $1.50. Little Folks’ Book of Verse . Contains the world-wide . Uniform 320 Tu Ramsey Net, $1.00 Mother Goose Clifton Johnson, Editor. A charming version, printed ona broad page in large, clear type with text wings. Square 8vo. 280 p Illustrated in duotone with line ig” ~ papers, etc., my ~. Will d others. ‘et, $1.50. Postag: GIF fr BOOKS Loves of the Poets Country, a ssopege. Full nah ig meet ; tis- Miss Siddals, Mary Queen of Scots and ers color. Box ed. Net, gee. "Postage ie coats: ts ‘e ns h va a en Sand e of Charles Dickens Chopin, s ee a i ~— — a bs ith ome lecorative bor , ete., sping vith over soo pictures. 3 Vols io on Ne, ee, By = Fahnestock. Net, me so. Postage =e ok of Scottish Poetry The Women of Senta George Douglas, Bart. Contains the repre- am Hard. i illiant treatment Net. ative poetry of Sc Geotlang. 8vo. 928 pages. —- changes in the status of women. 12m0, 300 fin Hy . a To a Pos vost i2mo. (Bu % Fully ill trated. Net, $1. Postage 12 cents. Th age The Life of David C. Broderick, a . Hig Bl = Senator | of the | F ne ed ck. A careful account of the part Jeremiah Lynch _, New edition, enlan 5 ed in ee Stuy by men pe French descent striking of ee — aed — = Bn on tho: research. Cloth. “448 pages geen tugs The Baker & Taylor Company Union Square North ra ee ive turned the tie in ‘a Vietsatek fe. 8.50 New York City JUST OUT American Permian Vertebrates By SAMUEL W. WILLISTON [, = HIS work comprises a series of monographic studies, with briefer | 4 notes and descriptions of new or little-known amphibians and e 2S) reptiles from the Permian deposits of Texas and New Mexico. EGS The material upon which these studies are based was for the most part collected during recent years by field parties from the University of Chicago. The book is offered as a contribution to knowledge on the subject of ancient reptiles and amphibians, with ‘such summaries and definitions based chiefly on American forms as our present knowledge per- mits. The work is illustrated by the author. Postpaid $2.68 228 pages 8vo, cloth Net $2.50 THE es OF CHICAGO PRESS CHICAGO - B -. ILLINOIS Contributions to Medical Science By Howard Taylor Ricketts Published as a Tribute to His oo, A His veers) under the Auspices of th hicago Pathological Society R. RICKETTS —e of typhus fever in the City of Mexico, May 3, Ioro. e was at ed by an insect, and thus point ace out the way for preventive measures. ese achieve- earlier ocky Mountain spotted fever, give Dr. Ricketts a high and ri able place on the records of medical The p t volume contains thirty papers on these and alii allied topics. Iti is rich in informa- tion of immediate ke and i in suggestions to — Baden goric Ms is also an impressive toa hose life = ay laid dent in the ¢ eves of humani 508 pp., 8vo cloth; net $5.00, domestic postage 3 3C. The University of Chicago Press Chicago Illinois A Laboratory Guide in Bacteriology By PAUL G. HEINEMANN Second Edition, Enlarged and Revised I ———— The Guide is confidently offered in the belief that it will commend itself, even ait than did the first edition, to elementary studen in medical bacteriology, the bacteriology oO the bacteriology and in water and milk, soil ba ie val cnet H 216 PAGES, mo, co POSTPAID The University of Chicago Press | Chicago, Illinois MOFFAT, YARD MOFFAT, YARD & COMPANY : Important F all Books & COMPANY CONTROL OF _ HE MARKET aad - 278 a y A Legal Solution of the Trust Sechicas lama. $1.50 net. Postage, 12 c is book desloge: ime bas principle of State Control convincingly, presenting a solution eerigee ‘ould result i : Eat peace. Thet as come for eae ead policies base ye nm the im aenes orial principle ote ete control of all businesses which hav ined undue rofessor Wyman urges upon all who hesitate to accept to the full his rogram of regulation, ‘that’ tt is the a alternative, it ther F deattetinn is to “= avoided. He believes that the law PD wo ald be satisfied with the recognition of its pee control the situation, and he feels that thereupon the law will abandon its campaign for the destruction of the GEN 3, AND OTHER ESSAYS ND CLARENCE STEDMAN ted by Laura Stedman and — ee M. Gould. $1.50 net. Postage, 14 cents A coll Spry inguished ess at body of material, the work of his maturity, left by Mr. Stedman at ah, eae "The veliing wall Hen in wae nthe Pedehanet ts essay on Genius which was published i in the Princeton Review in 1886, and occasioned gin witht itti d also contains essays on Keats, Blake, Landor, Whittier, R. H. er ya yowec’ Dobson, Bryant, a nd others. It is, no invaluable and a highly interesting volume from end point of THE my TRIAL, AND DEATH OF RANCISCO FERRER Laoag ARCHER vo, ap 00 | net. spinor 20 cents ee Illustrated. ae esi and rmeglevond account cat this rab radical a: P in Europe America a y THE CONQUEST OF dpe spapland NORTHWEST Large 12mo. Cloth $2. new edition in one alain published i in capcom so dea toa en demand ae a ert edition, contains all the Meco of the original two volume THE (GIFT OF SLEEP uthor of “The ee air ene ete. With a Introduction by essor Edward M. Weyer, erase and In h pone ee Postage, 12 ¢ ene Ca ere “Gift of Sleep,” - Bolton Hall shows how o own bodies wes minds teal nat ly for ¢t a iadine and perfection. He ang hg that Mental Se lence “to end itself to ordinary people must show efinite results that can be measured.” Mr. Hall points out ee science ‘ie us to sleep well sad to tat bi the init of turmoil, without a course a “going into the silence” of, or “concentration” or other artificial processes with vague d Edward M. Weyer, the distinguished Professor of Psychology in Washington and Jefferson College, writes an intro- ‘uction which shows that the boo appeals to scientific reason instead of to unproved theories. THE INTERPRETATION OF HISTORY 8vo, mg . re of at $2.18 CO I— History and the Writing of History. V.—Society and the Individual. i= tegen Voretinay =e Ras eta oi rae pomorp. we View of ycho f IV.—Man and Natu VIIL— The Quest ee This closely reasoned ye ill k t I to all tk 'y aes philosophy. A Manifestation of Creative Power, Directive Mind, and Ultimate Purpose y ALFRED RUSSELL WALLACE, O.M., F. vod oe w The descri wines! wi dios aol een te sr cabcnalite niet Aad ts ent of the doctrin f jientific min the argum of evolution by Snare waren is not a es powerfl than the ieeant iat ‘creative power, directive mind, and hate Purpose’ in progress of evolution.” —The Outlo MOFFAT, YARD AND COMPANY, Union Square, New York JUST OUT _ Eugenio Rignano On the Inheritance of Acquired Characters By BASIL Cc. HARVEY, University “of Chicago. With an Additional Chapter on gin and Nature war poset Tendencies Pp. cies Cloth, $3.00 TRANSLATOR’S paleace IGNANO is a student of Biology who soos also the traini ing of an A get: and pivsicies: He has studied biologi- cal problems thoroughly from that point. He offers in this book an explanation on a physical basis of assimilation, — cell —— and ‘dilreatioticn, ontogeny and the biogenetic a of recapitulation, and he suggests a _ echanism whereb e inheritance of Sat pe characters may be effected. ‘Such a study of "the most ete ake ce nd d iffic cult t of biological p roble ms ap ped o be of the greatest interest eeds 4 pe of Physics and Chemistry. University of Chicag "Ba ASTL Fp me deny flatly a es of ever arriving at an understanding of the nature of life. But if w ourselves in what this nee? tanding of the nature of lite pou consist, from the agate of view oh positiv a ilosophy, we have no ulty, i recognizing | that euek % understanding must be uced to pe vise: it ital hla wit aes er tuite ye awe suitably modified by gs part gg specia. al conditions imposed w it so a just these 2 special rene itions shall determine the differences — xist be- tween this vital phenomenon and the pheno: of the inorganic world most coeey related t If this b so, it is then the duty of science emphatically to reject such a denial of scientific thought as would be dees * pon this search for the nature of hg vit i v rey. consti utes the av atioth object and the final of all or rt study in general.” —. ignano, in‘ OPEN COURT SCIENCE SERIES The legge: | 4 Factors of Organic Evolution. By E. D. The Psychic Life of Mi Organi By Alfred - eset Illustrated. Cloth, $2.00 net. (ros.) Binet. Cloth, 75c. (3s. 6d.) lof Man. By Paul Carus. An Investigation The Reas By Alfred B = the Facts of Physiological and Ex Experimental a Tandiatet by pf oe ricer, BN aod Cloth, 75¢ oo pari oe ot tel egtea hang cat ee r, 85¢. age 6d.) 1th ology of the Nervous Sys By ii Cres. Con By Alfred Binet. io oth, i) bag soe oes aged $ bem wack, athe Soul of a recor toe ea ) je ¥ I 1 Laboratory Proved Hel The! Rise of Man. By Paul Carus, A Sketch of the Has the, Peychological Weg pi Origin of the Human , tng Illustrated. Boards, cloth ar _ Erte a. ae hake from the French by back, 75¢ net. (3s. 6d, net. s : A shag ane at logical Theory of Organic Evo- "By Tame’ Oc Vtce Tasha Geax PraMgeton, “ion iy Cast von Neve Sry ae (0 $5.60 net. eas et.) Expe n the Gen n of Insec of a8 riage r By Hugo De Vries. Comments on cesco Redi. oT ranslat aT the Italian edition of I a he Experime ts of f Nilsson ~ pavat Illustrated. by Mab Bigelow. Illustrated. Cloth, $2.00 net. (10 Cloth, gilt, $r. ae Pape Science and Faith, or Man as an Asia ger The Mutation Theory. By ‘He he Vries setPe as a Member of Society, with a Discussion 00 ments and Observations on A the Ori gin of Spec the Animal Societies. By Paul Topinard. Trans Vegetable peice. ar ote .) Numan usta ion, by T. J. McCormack. $1.50 net. wee 6d. esi | pl « Translated by Professor B. Farmer Prin eco A. D. Darbishire. Cloth, bee volum a © S00. net. irri epp meted orl Dek E. cana $1. fs ery rye llular genesis. Vri In- The Gospel According Darwin y enees on =) Fettiliztion ‘nd Hiybridization oe Bho aie) Cloth, $r. tg (6s.) ae 60c. Cloth, $3.00 net. ste A Ree Boo! e. n Organic Lae og By Bh aig D. Kasfost = On Sree ie Shut ite en especially for : stem. By sid the Sp 2 ge eyed bog ec to ilstrated, seven colored plates. 2d < Cloth, $1.25 ee ory of Nerve Activity.” 7sc net. (3s. 6d) (5s. 6d.) sh apg ated slated ser The at of th Will. By Th. Ribot. . 6d. jy Paper, On dont Selection as a Source of Definite Vari- by Merwie: Marie Snell Cloth, 7c. (35. 64.) ation. me August Weismann. praenied by T. J. 2 ‘Th. McCormack. Bag (1s. mT Pape bal =< “Exolution of of General Ideas. wf 25 ae e Sci of Mechani. By Exaes Mach. A nslated by Frances A. Welby. Cloth, $3.25- Crit tical and, Historical peo al its Development. Bao Soc ne Ribot. Translate fee J. McCormack. Illustrated. $2.00 Essay on the Croatios Imaginati (7s net. (9s. 6d. et.) Translated by A. H. N N, Baron: Cth, rs 75 3 net. a. Popular Scientifi ic Lectur By Ernst Mach. Trans- 6d. net.) Paper, $1.00 ni - late i He McCormaci, lustrated. $1.50 ‘net. “The Diseases of nha By Th. Ribot. Cloth, $1.5 (7s. 6d. net.) Pape Contri i ired Characters. Eenat Mack h. ve the Analysis af go Sensations. By Oi noni Westen 2 Peanalated by Basil C. Besa net faach, d.) Translated by C. M. Williams. $1.25 With an appendix “On the Mnemonic Origin Bev Nature of Affective Tendencies.” Cloth, $3-00 Space and Geometry i Fas 2 yg ot of ny “ag ate (z2s. 6d. net.) c Mac poate ee 8 Sec ~y 5 Oe nit ~~ ke = an “ve {aet Be eee Sa and a Di a a Dis prints path c Rootof the Princinleofthe Con. Sys» net. Part I The Rees, thoy, ci nie pe er jourtain. “cl _ $r. Fee, vss od) erat _, veoh § $r.5 See. Pa I x “Post Darwin 75¢. Meat 6d.) Paper, porno Hage y Th. Ribot. Cloth, pags s: Isolation a Physiologica e Personality. &B Th. nism. By 75. Ge. 64.) Paper, 30c net . Ribot. Cth, An Kemeetee oe Paper, 4oc fs THE OPEN COURT PUBLISHING COMPANY d Modern. Publishers and: Importers of Standard Books on af mar y, Science, — the History of Religi ns, Ancient an i D romied in 1887 by Edward C. irars er, f ie the Beton of e tabling religion upon e Sci ientite 1 U S.A. rawer rr. Send for eeuia Hlatiad catalog CHIC i Walker Prizes in Natural History the provisions of the will of the late Dr. William Johnson Walker two prizes are annually offered by the Boston Socrery or Narurat History for the best memoirs written in the English language, on subjects proposed by a C ittee appointed by ncil. For the best memoir presented a prize of sixty dollars may be awarded; if, however, the memoir be one of marked merit, the amount may be increased to one hundred doll t the discret f the Committee. For the next best memoir a prize not exceeding fifty dollars may be awarded. Prizes will not be awarded unless the memoirs presented are of adequate merit. The competition for these prizes is not restricted, but is open to all. ttention is especially called to the following points: 1. In all cases the memoirs are to be based on a considerable body of original and unpublished work, accompanied by a general review of the literature of the subject. 2. Anything in the memoir which shall furnish proof of the identity of the author shall be considered as debarring the essay from competition. 3. Although the awards will be based on their intrinsic merits, preference may be given to memoirs & evidence of having been prepared with special reference to competition for these prizes. Pee, i oT st be accompanied by a sealed envelope enclosing the author’s name and super- scribed with a motto corresponding to one borne by the manuscript, and must be in the hands of the Secre- tary on or before April rst of the year for which the prize is offered. 5- The Society assumes no responsibility for publication of manuscripts submitted, and publication should not be made before the Annual Meeting of the Society in May. Subject for 1912 and 1913: Any biological or geological subject. GLOVER M. ALLEN Boston Society of Natural History raped Boston, Mass., U.S.A. Morphology of Gymnosperms Joun M. CouLTerR AND CHARLES J. CHAMBERLAIN N 1901, Coulter and Chamberlain published their “Morphology of Gymnosperms, which brought together in organized form the results of research up to that time. The book was based partly on original work by the authors and partly on material from the reports of other investigators, and it at once took its place as the standard work On the subject. (eee The University of Chicago Press Chicago, Illinois ns eEeEeeneneey eee BRIEF DESCRIPTIONS OF IMPORTANT. NEW BOOKS YVES DELAGE The Theories of Evolution By YVES DELAGE, Professor of Comparative Zodlogy, Anatomy eae Physiology at the University of Paris; member of the Tastitute, ot a GOLDSMITH, M. rigs editor of l’Année Biologique. Translated into English by ANDRE . $2.00 net; prepaid, $2.2 A well-known professor at Sean s: “T have read it with ae pleasure and profit and am oy ge ee that we ha ve not seen references to it before. It is a popular exposition of the present status the standpoint of a well-informed critic. The name of Delage alone wou wuld ensure a In its wi tieal aspects it is more complete than any of these” frifecring to similar works in En ELLEN KEY Love and Ethics Translated by AMALIE K. BoGusLawsKy. 12mo, 50 cents wet; by mail, 56 cents In her latest book, the author deals chiefly with the influence of the ultra ancien spirit of the times on an effete pacer of the moral law. She Keng a eel out asd need of a higher e thical ideal and greater freedom of choice in the relation Between n, and insists that the in ividual attain his highest sag yr bed y a conscientious fulfillment. of | his duty to society. s supplements “Love and Marriage,” ich she awakens the social consciousness by cnigeting radical changes in our or- ganization of ie LEO | N. TOLSTOY What Tolstoy Taught Edited by Botton Hatt. 12mo, cloth, $1 1.50 net; by mail, $1.62. but comp y few are familiar with his philosophy and religion except as they are disclosed in his fiction. The p t e Russian prophet’s life- work practically in his own words. The subjec ects are classified and indexed and ts book affords an pat ce hang to all desirous of acquainting hccaschvek with Tolstoy’s teachings without reading his m: TOM. L. JOHNSON My Story ited by Exizaseta J. bier oe Fully ot ee romo, cloth, $2.00 net; by mail, $2.20. The last rs yeah nll Tom L. Johnson’s life were devoted wat the eas of a narrative of his struggle with s ege. But this — ted a discussion litical and poe relations and the wor became a pb of his life. This f ng sutobiogrephy—the i ncredible account of a self-made man who, converted to a new principle, janheincen orldly gain w e had trium Se handle acquired it ¢ . ve himself to the the realization of pe ideal—is ra of the pore at ‘the economic evolution of the Unit ah : itic tat capitalists, noble and base, his Baydicke 9 ation with Henry George, his successes as an inventor, his 4 of municipal problems while Mayor of Cleveland are only a nae af the suk subjects which he wrote ©: CHARLES H. BRENT The Sixth Sense (In The Art of Life Series) r2mo, , cloth, 50 cents net; by mail, = cents Sieh by andra see gestions, and its dangers when limi sng sphere aed disclosed d. The ‘aathor develops his thesis so convincingly that the sixth rome t-present force to his re JOHN NOLE be ak te agi ye egplanning Small Cities This is the first book to result from the widespread movement to remodel American cities. a ee ce towns: a Va.; San Diego. Cal.; Montclair, N.J.; Glen Ridge, N.J.; Rea hte at : wi IMPORTANT NEW FICTION HERMANN SUDERMANN GERHART HAUPTMANN The Indian Lily The Fool in Christ These are new publications: send for catalogue of earlier books of equal significance ee B. W. HUEBSCH, Publisher 225 Fifth avenue New York aoe VOLUME LII NUMBER 5 FHE ISO LANICAL... GAZETTE NOVEMBER 1911 REVERSIBLE SEX-MUTANTS IN LYCHNIS DIOICA' GEORGE HARRISON SHULL (WITH FIFTEEN FIGURES) Six hermaphrodite specimens of Lychnis dioica L. were found in cultures of 1908, and eight in r909. With respect to their heredi- tary behavior in the first generation, when used as pollen parents, these hermaphrodites proved to be of two kinds, the individuals A and B being capable of determining the hermaphrodite character in their male offspring, while individuals C and D behaved exactly like normal males, giving progenies @nsisting of females and nor- mal males. The conclusion was reached (SHULL 26) that the hermaphrodites are modified males, because (1) in all families in which the first mentioned type of hermaphrodite was used as the pollen parent the offspring consisted of females and hermaphrodites in the same — ratio as would have been expected of females and males if a normal male had been used as the pollen parent, and because (2) the second type of hermaphrodite when used as a pollen parent gave the same result that a normal male would have given. Accepting tentatively the Mendelian explanation of sex first clearly enunciated by Correns (6), which recogirizes the one sex as homozygous and the other sex as heterozygous with respect to a Sex-producing gene, it was decided that these hermaphrodites (and therefore also males) must be heterozygous, because (1) the males are capable of being modified in such manner as to display function- : * Read at the meeting of the Botanical Society of America, Minneapolis, Decem- er, IQIo 329 330 BOTANICAL GAZETTE [NOVEMBER al organs of both sexes, and because (2) self-fertilized hermaphro- dites produce dimorphic progenies, consisting of females and hermaphrodites. In my first paper on the inheritance of sex in Lychnis (SHULL 26), I represented the sex genes by the conventional signs for the sexes (9, 6, and ¥). As these signs were used in my tables with two different meanings—to represent sometimes the character of the genes and at other times the character of the soma—lI suspect that readers may have experienced some difficulty in comprehending the tables. I shall therefore adopt here the plan usually followed by students of genetics, of representing the genes by letters, letting Ff be respectively the presence and absence of a female determiner, Mm a male determiner, and Hk a hermaphrodite determiner. The conventional signs for the séxes will be used in this paper only in their more usual signification, referring to the nature of the soma, that is, the sporophyte. If Correns’ view of sex determination is correct, and the males are heterozygous, the females must be homozygous. CastTLe (5) suggests that in such a case the females will always be positive homozygotes, having a pair of sex genes (FF) corresponding with a single equivalent gene (Ff) in the male. I do not believe that this view can be substantiated, as there seems no good reason why females should not be negative homozygotes in some plants and animals, “neutral”? homozygotes in others, and positive homozy-- gotes in a third class. If the females are positive homozygotes, the somatic formula of the two sexes may be represented thus: FF=3, and Ff= 4; if the females are negative homozygotes, the correspond- ing symbols will be FFmm=, and FFMm=<é; and if the female is a “neutral” homozygote, the formulae of the two sexes will be FF=$%,and FM=4. Only the first two of these assumptions cor cerning the nature of the females were considered in my earlier paper, and either was found capable of explaining the results secured in the first generation, provided the presence of a partially jnde- pendent hermaphrodite factor (H) might also be assumed. Whether there was any genetic relationship between the her- maphrodites A and B which produced hermaphrodite offspring, and C and D which produced males, could not be determined in the first 1gr1] SHU LL—REV ERSIBLE SEX-MUTANTS 331 generation, and two explanations seemed possible: (1) these two types of hermaphrodites might be respectively homozygous and heterozygous in regard to a modifying factor H, whose presence was assumed, on the suggestion of CorRENS, as possibly necessary for the change of a normal male into a hermaphrodite; (2) the hermaphrodites of the second type (C and D), which gave first generation progenies equivalent to those produced by normal males, might owe their hermaphrodite character to some accident of development which affected the soma alone, leaving the germ cells unchanged. In this case they might be appropriately called “somatic hermaphrodites,” to distinguish them from those of the first type (4 and B) which transmitted the hermaphrodite char- acter to their male offspring and which are therefore to be recog- nized as “genetic hermaphrodites”’ or true hermaphrodite mutants. Neither the character of the females nor the relationship of the two types of hermaphrodites could be determined from the results of the first generation, but it was obvious that at least a partial solution could be expected from the second generation. To attain this end a large number of crosses were made in 1909, by using hermaphrodite individuals and their derivatives in various com- binations with each other, with unrelated females, and with normal males. The offspring of these crosses were grown during the sum- mer of 1910, and the 104 families produced from them included 6132 individuals which came to bloom and of which the sex was tecorded. These records were made in the writer’s absence by Mr. R. Cattin Rosz, to whose energy, faithfulness, and care it gives me pleasure to testify. In order to comprehend fully the problems involved, it will be advantageous to consider some assumptions which were permitted by the results of the F, crosses, and whose availability is partially tested in the F, families reported in the present paper. In this Connection it is also important to consider briefly the “presence and absence” hypothesis, a full discussion of which, however, Would require too great a digression. Although this so-called hypothesis is frequently referred to by students of genetics, I am not aware that it has ever had a very definite formulation, and it would undoubtedly be defined differently by different students. 332 BOTANICAL GAZETTE [NOVEMBER ‘‘Presence and absence” came into use in the first place, simply as a convenient method of expression to avoid the confusion which arises when the same dominant character is described as an alterna- tive of several different characters which are hypostatic to it, and which may themselves be present or absent in any particular instance. The very general applicability of this mode of expres- sion naturally suggested to various writers (Hurst 18, SHULL 27, etc.) that it might have a more fundamental significance than merely as a convenient form of description. These authors considered it simpler and more practical to suppose that the heterozygous genes are unpaired, and that the “absence” of a character? is unrepresented by anyinternal unit corresponding with the gene which determines the “presence” of that character. The “presence and absence” hypothe- sis need not be associated, however, with the conception of unpaired determiners in the heterozygote, for in any pair of organs there may be present a function or feature in one member of the pair which is absent in the other member, or both members may be alike in kind but different in quantity or activity, the differential between the two being in this case the determiner of the alternative characters involved. This excess in one member of the pair would be present, of course, in that member only, and must be absent in its mate. Whether the hypothesis of unpaired genes or that of paired genes represents the true condition in any particular instance, and whether the absence of a character is absolute or only rela- tive, will not interfere in the least with the use of “presence and absence” as the most convenient method of stating a great majority of the alternative characters with which the student of heredity has to deal. For the application of these different phases of the “presence and absence” hypothesis to the sex problem in Lychnis, attention is directed to the following table: ? It is to be regretted that some writers have misconstrued the meaning attached by most geneticists to the expression “absence of a character.” The absence of the Angora character in cats, rabbits, ete, -» does not result i ina hairless animal, vee one with short hair. In Ocenothera ie event the production of Aaeeg in the amount and localization characteristic a 0. rubrinervis (see Gates, R. R., Studies on the variability and heritability of pigmenta- tion in Oenothera. "Deltech Tid. Abst. Vererb. 4:337-372. 1911). 333 SHULL—REVERSIBLE SEX-MUTANTS tgt1] BA e pues WW PUP YHA } a wai ato at WHWA wd | snOBK2030494 HT & puvs , TAN ee HHWd YY | SnosXkzowoy YT pur ‘TeaynoNn ‘SA *q oyun 8.5 ty Be damian amici e pues yu Ue Y Fue, Pegs oe cael bee As ut yy Ueut sno3Azo19}0 suorjdunsse 989 yy RPUVs | HAMM AT PCC YAMA yet HHY NAL | YYyMimyy | snosXzowoy 7 JO ssauqoa1I09 sy, pur ‘aaneson a103AzZOID}OY Ul eg pues YY fy PU YHA a yw paydnoo 7 YES Wael snosAzoia}oy fT & pues YLT pue YADA Se oe er ear ee ee HHL YY gapeey pur ‘sArqIso ayposydvurioy oyeuray S¥AVWAY SLTIASAa SNOILVNIGWO9 NOILdWOSSV SI WivNaa ‘IVOTaId Ny TVOILAHLOdA HT aaainday aHL NIHM AVINNAOT *H{ 10yvVJ ay} ul snosAzosajay puv snosAzowoy Ayaatoedsai av aytporydeursay jo sad} omy oY [—] NOLLAWASSV AUVANODAS ‘gTeulay ay} UI uoIssaidxe puy Jou. YOIYA ynq ‘oyporydeuy B 0} a[VUT oY} SaduRYD YOTYM PF 10JOV ayvAvdas ¥ SI aay J—] NOLLdWASSV AXVNIAg I ATaVL [NOVEMBER *T uorjduinsse Arvpuodes Jopun pojzejnqey Apvalye useq sey saypoiyd jr 8 ay3 ul snozA’ ] St A] OIA Ul aSwd MYT, y 8.4 tq Sv ous ss ty | § pues A Wy pure JJ Awa 7p pate ia - [eanoN wustqporydeur -Ioy yWusuvs} youuRd s,s | a pur s Hupwyg pue wus y |) uonnquystp souryD wl py tay UTE IF ig amasitae Sae DATION ayvul | 4 pur s Afy pue yay Afy da \'° peared sauary ondeuds @ sey wy ssaun 2 pur & Pate COOMERA Se hie ge hs anes ee . fly Aa | poaredun sauary dATTISOd aq JouURS 4 OUT, y[Nsal pynoos yey} suON ; pur ‘aatpIsog Avurt yr ‘9uo3 xos oy} Jo “Hf 30 ‘Hy “Ay £q paquasaidai oq uy} UOI}BOYIpou dATVVyNU BV Aq pasned Zuloq WsIyIporydeussy ‘77 10}9v] OU SI dI9Y[.—]] NOLLAWASSV AUYVWIN BOTANICAL GAZETTE QR pues Y4HWA PUre WYATT W Yt pafdnoo 7 Y4HWA ee [TeaqynoN S.A'd OAL a 8,20 Qpurs | YAM py] pur yymugy a. padnos 7 | YHM yyy | yymlyy | oaneson wistjiporydeuay YIM paydnoo 77 YHA YY TA aired sauary yusuvs} JouUv $s ore WHSA PAP {4A 4 07 o1ydiowoyayye 77 YHA YY TT ‘ahrodetl sauory pure ‘oatqisog ay porydeurey ayeuray | SaUVWT SLTASAA SNOILVNIGWOO NOILAWOASSV SI aTIVWad a TVOIMTa sy ‘TVOILAHLOAAY axurnday AHL NIHM AVIANAO,] | « H 9} yadser ur snosAzosajyay woy} st od4q.3s1y 04} pure ‘odAy ysry oY} 07 poyejoruN puv oFvWIOs Ayaind st ay{porydeutiay jo adA} puosas a4 .[—]] NOILdWASSV AUVANOOAS panuyuod—l ATAVL 334 1911] SHULL—REVERSIBLE SEX-MUTANTS 335 Particular attention should be given to only two points in this table until after the results secured in the second generation have been considered. The assumptions which form the basis of the first section of the table lead to the expectation (a) that females derived from hermaphrodite families, whether they be fertilized by normal males or by their hermaphrodite sibs, will yield families in which the male offspring are hermaphrodite and normal male in equal numbers; and (6) that the hermaphrodites of the second generation when used to fertilize females from normal male families will produce no hermaphrodites, but only females and males. The alternative assumptions involved in the second and third sections of the table, on the other hand, lead to the expectation that, re- gardless of the origin of the female, no hermaphrodites will be pro- duced normally, except when fertilization is brought about by sperms from a genetic hermaphrodite, and then the result will always the same whether this hermaphrodite was a mutant or whether it was derived from an antecedent hermaphrodite. We may now proceed to examine the results of the crosses. This will be most easily accomplished by considering each type of cross separately in the following fourteen cases. In the model | pedigrees, illustrated under each case, the oldest ancestors entered © in the diagrams are females and males both of which came from normal families, whose matings had been controlled during at least three still earlier generations, and which are known to have been in each such previous generation the result of crosses between females and normal males, and to have belonged to families in which no hermaphrodite mutants appeared. In the diagrams all male and hermaphrodite individuals which appeared as mutants are indicated as such, and it should be understood that any male or hermaphrodite not so marked was a member of a family which consisted of a normal proportion of its own type, that is, either male or hermaphrodite. : CASE I CROSSES OF GENETIC HERMAPHRODITE MUTANTS WITH FEMALES Only 2 of the 8 plants recorded as hermaphrodites in 1909, in otherwise normal male families, were successfully used for breeding. One of these, bred to 2 different unrelated females, produced 72 336 . BOTANICAL GAZETTE [NOVEMBER females and 88 hermaphrodites (nos. 09123 and og171). The other, bred to the same 2 females, produced 116 females and 53 hermaphrodites (nos. 09124 and 09172). The result of these four crosses, involving 2 hermaphrodite mutants, was therefore 188 females and 141 hermaphrodites, thus showing that these 2 hermaph- rodite mutants were of the same character as the two denomi- Pedigree no. Result | Pedigree no. Result ~ ST 0809 veers eterna GRSi 400 28-1) OBI50. ee 509:43% O8106..... 2.6.6... eee 532: 508 OGE SS eras Suna eta es es 362253 OUEED cect Ph retrace GOP BOGIES VT OOI IR. oc OOS iis seas 522: 30% Soke 1 Oa ne 512.528 COI7T 65 ies 3697358 08128... 1... eee. 502: 518 ned wa Top aiore eae S| Saree 649: 239 COLAGE a eee 672:335 sic ghee Soke lla . | tk: See ee 5862: 4468 : 26 ee nated A and B in my earlier report. For the sake of completeness, the crosses of A and B already reported are included in the tabula- tion of these crosses, the total progeny from this type of cross being 586 females, 446 hermaphrodites, and 2 males. : 586 446 Fic. 1.—Model pedigree for case I Two other individuals, which had a derangement of the sexual characters of such a nature that the lobes of the calyx were trans- formed into stigmas, and in one instance a small ovary with appat- ently functional stigmas was present in the center of the flower and git] SHULL—REVERSIBLE SEX-MUTANTS 337 associated with functional stamens, were of such anomalous char- acter that they have not been included among the 8 recognized hermaphrodites found in normal families in 1909, but they will be mentioned later under case XIII in connection with the somatic hermaphrodites C and D of my preliminary report. CASE II WHEN GENETIC HERMAPHRODITE MUTANTS ARE SELF-FERTILIZED Pedigree no. Result ? ( a. be ks boat ee a eee 249%: 1909 OR Pe toe eis os ch ca eae os ee lee 99: 68 Pires re oe ek I10%: 95% —$$$$— Pt et a eae ee | 1439:1209 (Mutant) o Sef None of the new hermaphrodite mutants discovered in 1909 were successfully self- | “| fertilized, and the pedigrees here reported are repeated from my former paper for the : fe) sake of completeness. Al the self-fertilized 143 120 hermaphrodites which yielded progenies in Pus 5 ---Model pedi- my 1910 cultures belonged to a later genera- gree for case IT. tion, being offspring of a self-fertilized her- maphrodite and not the progeny of new mutants. They conse- quently belong to a separate case and will be considered next. The agreement of these results with those under case I leads to the con- clusion that the eggs of the hermaphrodite are all of one type, that is, female-bearing, like those of the females. The significance of this result will be considered later. CASE HI WHEN F, HERMAPHRODITES ARE SELF-FERTILIZED Pedigree no. Result Pedigree no. Result ie easiest se dots CACM aati es cat 59: 88 Obste cew isa e res 16%: 9¥ : aha CT ee IS 172%: 6% Os ee ye: MOTE ike nein yok 189: 23% $s Pee et —~ 5? ik dah ER nS ee 69: 10818 |} 09220...--+- eee ert : FEO os i cin oa es 1g Boe a, eee eee 439: 388:16 otal ci sees 1479: 1018235 ees eee ne ey 338 BOTANICAL GAZETTE [NOVEMBER The first four of these families were produced by self-fertilizing 4 individuals of pedigree number o8115, and the rest by self- fertilizing 6 individuals of number o8119. Most of these families were too small to show obvious differences in the genetic compo- sition of the different parent plants, or between them and the hermaphrodite mutants tested | 2 ae under case II. The small size of the families is due to the comparatively poor develop- ment of the ovaries and stig- (Mutant) O Xsut mas in most hermaphrodites, and the consequent difficulty | of securing large quantities of seeds by self-fertilization. OXset Most of the attempts to self- fertilize the hermaphrodites resulted in failure, and only in a small proportion were any 2 oO o seeds produced. The total (Mutant) result agrees with results ie a 3 secured from the observation Pi® 3-— Model pedigree for case 111 of larger families, and it is fair to assume that the rela- tively large differences shown by some of. these families are not significant because of the smallness of the progenies. This con- clusion will be fully justified I believe, when it is observed under case IV that the very same plants, which produced the somewhat variable progenies shown above, gave uniform results when they were crossed with an unrelated female. CASE IV WHEN HERMAPHRODITES FROM THE PROGENY OF A SELF-FERTILIZED HERMAPHRODITE ANT ARE CROSSED WITH AN UNRELATED FEMALE The families 09133 to 09142, inclusive, resulted from pollinat- ing different flowers of a single female, 08114(4), with the pollen from to different hermaphrodites taken consecutively in family 08115; and the remaining 19 families were produced by pollinating the same female, 08114(4), with pollen from rg different hermaphrodites 1911] SHULL—REVERSIBLE SEX-MUTANTS 330 in family o8t19. This series of experiments, like those under case IIT, was calculated to discover any genetic differences which Pedigree no. Result Pedigree no. Result 442:203:14 OGTSALGWH YS Saree aes 579: 263 §52:278 OOTES ee os ee 489: 423 4195375 O0156. cee 549: 418 422: 31% OO1S7 Cty ek ere 562:328 473: 33% OO1 SS eo aa nw sey SG 592:259 472:378 OORT i. oe ees 512: 298 508: 298 OOIQO RS is ie eigen ee 432: 29% 659: 259 OO1OT cise ee 529: 298 382: 348 Opthz eo 259: 30% 51%: 40% OG104. os see 562: 332 522: 258:14 O9104 Se ee 169: 14% 49%: 308 OOIO§. 0. Ss Pane 462: 409 512245 OQN0G 2. Sis oy 362: 19% 662:243:16 || 09167 362: 190% 492:229 ates foe Total... oes see \13829: 867%: 36 might exist among F, hermaphrodites, and the fact that these 29 different individuals when crossed with a single female produced e's ie |__ (Mutant) es fe) on 1382 Fic. 4.—Model pedigree for case IV essentially identical results leads to the conclusion that no such Senetic differences existed. This conclusion is apparently open to | | | 5 fom 7 3 340 BOTANICAL GAZETTE [NOVEMBER but one criticism; the characters of the female chosen to be the mother of all these families might dominate such different char- acters as were possessed by the hermaphrodites, in which case all families would show identical composition regardless of the variations in the pollen parents. This suggested dominating in- fluence of the female is rendered untenable, however, by the fact that the same female was pollinated by 7 other hermaphrodites having different histories from those considered under the present case, and also by 11 different males of diverse origin, and in every case the males among the progenies were of the same type as their pollen parent. CASE -V WHEN FEMALE OFFSPRING OF SELF-FERTILIZED HERMAPHRODITES ARE CROSSED : WITH AN UNRELATED MALE Pedigree no. Result Pedigree no. Result Poorer OOLTA ee ee 219: 84 BOIGG eo fo ees 492: 226 OL IG sik es 509: 344 ia ee ee Oe 289: 256:1% OR os cs. S49 WOOttE ) OGIOG. ose eee ens 332: 236 eR eS a 392:114 eS Ree or on) SOR: See OOLOT ty 362:17¢ 09200 a ee | 269: 226 OM ie iS: 448590" 09203-6524. eee 229: 176 OOlGO a i 123: 66 OBIE. es cee 219: -326 TO Cn te 4719: 3055:4% Rees These families were produced by pollinating 14 different females, taken consecutively in o8115, with pollen from a single normal - male, 0855(36), in an unrelated family. The essentially equal results of all these crosses indicate that there are no differences among these females which were not dominated by the sex char- acter of the pollen parent. As this pollen parent was a male from a normal male parentage, it may be appropriately assumed to have been free from any hypothetically possible hermaphrodite modifier H. If such a modifier had been possessed by any of these 14 females, a more striking evidence of that fact should be presented than is found in the occurrence of less than 1 per cent of hermaph- rodite individuals among the offspring. This is a smaller percent- age of hermaphrodites than has been found in one or two cases among the offspring of a female pollinated by a normal male, neither 1911] SHULL—REVERSIBLE SEX-MUTANTS 341 parent having had any hermaphrodite connections. It appears fair, therefore, to consider these four hermaphrodites simply as mutants, and not as genetic derivatives from their maternal grandfather. The few hermaphrodites occurring in the families in- cluded under the present case may be related to the fact, however, that the females belong to a hermaphrodite family, for the same male 0855(36) was crossed with seven other females and with one hermaphrodite, and among the 443 offspring produced there were no other hermaphrodites. = 2 \—_ mm OXe 2 of rf Ee | | | | oe a 471 305 4 Fic. 5.—Model pedigree for case V Allowing for the same frequency of occurrence of hermaphrodites as shown in the table above, there should have appeared among these 443 individuals derived from the same male crossed with other females at least two hermaphrodite mutants. This number is so small that they may possibly have been omitted through the €rrors of random sampling, but the suggestion may be made that while a female cannot transmit hermaphroditism to its offspring, it may perhaps supply an intracellular environment favorable to the mutation of the male genes into hermaphrodite genes. 342 BOTANICAL GAZETTE [NOVEMBER CASE VI WHEN THE DAUGHTERS OF A SELF-FERTILIZED HERMAPHRODITE ARE CROSSED WITH E OF THEIR HERMAPHRODITE SIBS ‘ Pedigree no. Result | Pedigree no. Result OOTP kn ee i: 62: 2% RQS Ati wo ok 92: 28 OR ei ey Pet le 239:133 OGIO cee ee ee ee 302:179 OE Foie ou ee as sie iy hs SOLO esse ee es 482: 6% at a(S ON Si Seo a ne 459: 289 OOLOs ea ave eee 403: 20% ers es ee aoe re aa 639: 16% (sy log Wa pee ohare cen ar is 40f: 7% RR ey ath ahi ss ok ws 49: 38 POR en ee inion 35%: 102 8 = OED a 369: 7% OOI05. sos as sree ge: 7% otal. aes 4292:155% The seed parents of these families were the same 14 females which produced the families considered under case V. In the present case they were all pollinated by a 2 oe single hermaphrodite, 08115(9), in the family to which they themselves belonged. The results correspond closely with those of the last section, except that in this case the males (Mutant) 2) X Self were invariably hermaphrodites, showing as before that the character of the pollen parent — determines the sex character of the male — offspring. It may be noted that most of Q o these families contained a strikingly high per- centage of females, as compared with those under case V, there being 73.46 per cent of females among the progenies of case VI, and only 60.7 per cent among those of case V- 2 fe) The meaning of such differences in the sex 6 ree ratios is quite unknown at the present time, fia 6 Mody peal. and no discussion of the series of experiments Side fod cane VL. which are in progress for the purpose of finding an interpretation of such variable ratios will be undertaken here. It is believed, however, that the question of the sex-ratios constitutes an altogether different prob- lem, and has no direct bearing upon matters relative to the genetic’ interrelationships of the different sexual types, which are alone under consideration in this paper. Torr] SHULL—REVERSIBLE SEX-MUTANTS 343 CASE VII 5 WHEN HERMAPHRODITE OFFSPRING OF AN OUT-CROSSED HERMAPHRODITE MUTANT , A CROSSED WITH UNRELATED FEMALES ] Pedigree no. Result | Pedigree no. Result ee et. 362:188:14 OGIIS So tree a ee 462: 428 a eo ee) 562:318 WEES ey oe es 462:498 pe op oe 79°32 OO140 ek es 502: 309 fi A SN pet aa 202: 148 ODLAS ee ae 5523248 a oe 392: 269 00200) rer ae 269: 278 i he oa 472:19% Total no eas 4282: 2929:18 These families are essentially similar in nature to those con- sidered under case IV, except that in the present case the mutant was Crossed with an unrelated female instead of being self-fertilized. The first 7 of these families were produced by crossing 7 different 2B otmm 292 I Fic. 7.—Model pedigree for case VII hermaphrodites in 08118, upon a single female, o8109(1); the next three (09145-09148) were the result of using three of the same hermaphrodite individuals in the pollination of the female, 08114(4), Which was used as the seed parent of all the families included under 344 BOTANICAL GAZETTE [NOVEMBER case IV. The genetic equivalence of the different hermaphrodites again stands out clearly in these results, and when the ratios of the two series are compared, it is found that the percentage of hermaphrodites produced by the hermaphrodite offspring of a self-fertilized hermaphrodite is slightly lower than that produced by the offspring of these cross-bred hermaphrodites, the former producing only 38.2 per cent of hermaphrodites and the latter 42.6 per cent. The difference is too small to be of significance, particularly in view of the fact that much wider differences than this are found in families produced from different seed capsules on a single plant when pollinated by a single male. It might have been expected, perhaps, that a self-fertilized hermaphrodite would have produced a larger percentage of hermaphrodites than would be produced by the same hermaphrodite crossed upon a female of a normal family. The fact that such a result does not appear is further proof that, although the hermaphrodite is a heterozygote, its egg cells are of a single type and like those of the normal females. The last family under this section was produced by crossing 4 hermaphrodite of 08128(16) upon a female in a genotypically distinct strain of Lychnis dioica, received several years ago from the vicinity of Harrisburg, Pennsylvania. The result is quite the same as in the other families, all of which were derived from 4 common stock secured at Cold Spring Harbor, Long Island. CASE VIII ; WHEN HERMAPHRODITES ARE POLLINATED BY NORMAL MALES Pedigree no. Result ete 219:116:23 OO7TS oF. Bee gee oe $2: 16 cy ee ee tee 292:128:29 I have already remarked the difficulties encountered in the use of hermaphrodites as self-fertilized seed parents. The difficulties are still greater when the problem requires the crossing of the hermaphrodites with other males, for nearly all the numerous castrations which have been made have resulted in the dropping 1911] SHULL—REVERSIBLE SEX-MUTANTS 345 of the flowers without further development. Only one family (08116) was produced in 1909 from a cross of this kind. It was to Bees L__ L__ © mtutant a Ee | @ | | 2 of g (Mutant ? ) 2I Fic. 8.—First model pedigree for case VIII Een a " c 1 (Mutant) OX Self 2 ne | —— of oe © 8 I FG. 9.—Second model pedigree for case VIII Teported upon in my preliminary paper, and is repeated here. The occurrence of two hermaphrodites in this small family suggested that the hermaphrodite character might be inherited from the 346 BOTANICAL GAZETTE [NOVEMBER mother as well as the father. On this account the cross between hermaphrodites and males must be considered the most important of all combinations in interpreting the relations of the sexes. The difficulty involved in the castration of the flowers permits the question whether the two hermaphrodites may not have been due to a faulty technique, for males produced from unintentional self- pollinations would be hermaphrodites.s Special efforts were put forth in tg09 to secure more crosses of this character, but these resulted in a single success, and that of so limited extent as to be wholly indecisive. The 9 offspring of this cross (09215) consisted of 8 females and 1 male, so that the little evidence which such a small family can give is in harmony with the proposition that the character of the female parent has no influence upon the sex char- acters of the male offspring, except possibly by supplying an intra- cellular environment which is favorable or unfavorable to the occur- rence of sex mutation, suggested under case V. Continued efforts are being made to secure more data from combinations of hermaph- rodites with normal males. CASE IX WHEN HERMAPHRODITE OFFSPRING OF A HERMAPHRODITE MOTHER AND NORMAL MALE FATHER ARE CROSSED UPON AN UNRELATED FEMALE Pedigree no. Result OA ae oe 382: 389 OOLEE eS at a, Vie sik 519:33% OTAL Oe bos ity S92: 719 . The appearance of 2 hermaphrodites in family 08116 of case VIII immediately raised the question whether they were true genetic hermaphrodites like A and B, or whether they might not be somatic hermaphrodites whose hermaphrodite character was not in any way related to the fact that they were the offspring of i hermaphrodite seed parent. If they should prove to be somatic 3In a family grown in ror1 from a cross between a white-flowered hermaphro- dite and a homozygous blue-flowered male, all the offspring were blue-flowered and several (less than 6 per cent) were hermaphrodite, thus showing that such hermaph- rodites are not in this instance due to any unintentional self-fertilization. 1911] SHULL—REVERSIBLE SEX-MUTANTS 347 hermaphrodites, they would be in reality of the same genotype as their pollen parent, thus offering no exception to the general rule that the male parent determines the sexual type of its male offspring. Both of these hermaphrodites were crossed upon female 08114(4), already mentioned in cases IV and VII. No influence of the male grandparent appears, as all of the male offspring in these two eg Fg A Fic. 10.—Model pedigree for case IX families were hermaphrodites. This result proves that the 2 hermaphrodites of o8116 were genetic hermaphrodites. One of these hermaphrodites was also self-fertilized and gave a progeny of a single hermaphrodite, constituting family number 09210. It would be rash to draw a conclusion from a family consisting of a single individual, and nothing could have been derived from it if by chance that individual had been a female. The fact that it was hermaphrodite instead of normal male, however, confirms the con- clusion that the hermaphrodite parent was a genetic hermaphrodite like its own seed parent.. Whether these two hermaphrodites owed their hermaphrodite character directly to their hermaphrodite mother, or whether it 348 BOTANICAL GAZETTE [NOVEMBER resulted from a mutation of the male genes received from their father, cannot be definitely decided, but further experiments are in progress to test the possibility that the eggs of hermaphrodites can carry hermaphroditism and may therefore sometimes transmit it to their offspring. The evidence thus far is against their doing so to any considerable extent. CASE X CROSSES BETWEEN FEMALES AND THEIR HERMAPHRODITE SIBS IN A FAMILY PRO- DUCED BY CROSSING HERMAPHRODITE AND MALE Pedigree no. Result BOF ac ele Sih Seis Sie eee ace ae | QQ20G i ye a tee 29>: QUtt BOO ee, fue ee a es 462: 308:14 OOGLt foros cee 309:17% BED ee ee ak va eee 322: 16% LOCAL ee ee 1279:738:26 These are crosses in which the same 2 hermaphrodites of o8116, discussed in case IX, were used as the pollen parents in crosses with i tg i | 0 (Mutant) St bo J Q fe) (Mutant ? ) = fe) : St (Mutant) 73 = Fic. 11.—Model pedigree for case X tort] SHULL—REVERSIBLE SEX-MUTANTS 349 three different females in the same family. The results may be compared with those under case VI, where sib crosses were also dealt with. The comparison shows that the results were identical, though in one case the parents were the progeny of a self-fertilized hermaphrodite, while in the other the parents resulted from the ctoss of a hermaphrodite fertilized by a male. Thus is given still further evidence that these hermaphrodites in 08116 were genetic hermaphrodites and that such hermaphrodites are of like hereditary capacity, whatever their origin. CASE XI WHEN DAUGHTERS OF A HERMAPHRODITE MOTHER AND MALE FATHER ARE CROSSED WITH AN UNRELATED MALE Pedigree no. Result 007008 es, Pos eo OG2T Fe ae 108: 84 OOF eva eas 3392256 Lota eee 502: 344 The first of these families (09206) had the same seed parent as the first two families (09207 and 09208) under case X, and the ae. a ey — | aa ¢ of J g g 50 Frc. 12.—Model pedigree for case 350 BOTANICAL GAZETTE [NOVEMBER second (09213) had the same seed parent as the last two families (og2tr and og212) under that case. The pollen parent in all three families of the present case was the same normal male, 0855(36), that was used for all the crosses in case V. It is consequently fair to assume that the differences in the result under case X and case XI are wholly referable to the male parent, and that such differences as appear between case X and case V are referable to the seed parents. There is no difference in the latter instance, while the fundamental difference in the former is that in case X the males were hermaphrodite, while in the present case they were normal males, thus showing again the correspondence between the male offspring and their pollen parent. CASE XII WHEN MALE MUTANTS ARE CROSSED WITH UNRELATED FEMALES Pedigree no. Result OOTAI Se ee Beles ck 402:406 O0240 ne ik ek 432:446 OAL oe ers 839:846 It will be recalled that among the 705 offspring produced in 1909 from crosses between females and the genetic hermaphrodites, A and B, there were 2 males and 305 hermaphrodites. In similar manner it will have been noted that in a number of the cultures of 1910 a very small percentage of such males have appeared in families of which the male offspring were generally hermaphro- dite. Instances of this kind are noted above, under cases I, Ill, IV, V, VII, and X. Whether these males were true males or PpOS- sibly somatically modified hermaphrodites may now be considered. The families reported under the present case were produced by pollinating two different unrelated females with pollen of 08118(13), one of the two males derived from genetic hermaphro- dite fathers in 1909. No hermaphrodites were produced, thus showing that the pollen parent was a true male, and not a hermaph- rodite which had suffered the suppression of the female organs because of some purely somatic influence. The frequency of occurrence of such male mutants may be inferred from the fact 1911] SHULL—REVERSIBLE SEX-MUTANTS 351 that 11 of them appeared among progenies comprising a total of 3331 females and 2126 hermaphrodites. In other words, they constitute about o.2 per cent of the total progeny of the genetic hermaphrodites when the latter are used as pollen parents. In no single family did more than one such male mutant occur. While these numbers are too small to allow an accurate estimate of the fe 2 fof : ore OF Mtant | Fic. 13.—Model pedigree for case XII relative frequency of hermaphrodite and male mutants, the evi- dence seems to indicate that there is no striking difference between the capacity of males to give rise to hermaphrodite mutants, and that of hermaphrodites to give rise to male mutants, though male mutants have appeared with slightly greater frequency than hermaphrodite mutants. CASE XUI WHEN SOMATIC HERMAPHRODITES ARE CROSSED WITH UNRELATED FEMALES Pedigree no. Result OST2e ca eas 3902:556 O8152 vig eae cans 269:186 OOS. ewe eyes 569: 266 0000: bis eis eee whee eee 632:34¢ Totek 6.3 esr 1849:1336 itarcigeeentencm ten 352 BOTANICAL GAZETTE [NOVEMBER The pedigrees 08125 and 08132 are those of hermaphrodites C and D among the cultures of 1909, which were reported upon — last year. If the “model pedigree’’ illustrated in the diagram (fig. 14) be compared with that under case I (fig. 1), the two will be seen to correspond perfectly. In fact, the hermaphrodites A and B included under case I were full sibs of hermaphrodites C and D whose progenies are repeated here. These 4 hermaphrodites which were found in the cultures of 1908 were indistinguishable fe 2 LJ -L4 —+0 1 ] Fic. 14.—Model pedigree for case XIII _ from one another in their external characters, and the fact that they belonged in two different categories was only demonstrated by the breeding tests. No additional instances have been found in which a hermaph- rodite indistinguishable from the usual type of “genetic hermaph- rodites” has proved to be simply a somatic variation of the male. However, 2 peculiar variant individuals found in one family of the 1909 cultures exhibited an analogous behavior, and consequently their progenies have been added to those of C and D under this case. The 2 individuals used as pollen parents of the families 0995 and og96 had several lobes of the calyx prolonged and modified to the form and structure of stigmas, and one of the flowers had in the center a small unicarpellary ovary with an apparently functional stigma. Both of these plants had func- tgr1] SHULL—REVERSIBLE SEX-MUTANTS 353 tional stamens, and both approached more nearly to the type of normal males as the season advanced. On account of the anoma- lous position of the stigmas in these plants, they are not to be included in the same class with the other hermaphrodites which have been considered, but it may not be unfair to accept the appear- ance of stigmatic calyx teeth in these male plants as additional evidence that the male is heterozygous in regard to sex, but nor- mally has the presence of the female character completely hidden by the dominance of the male character. A somatic derangement may be assumed as the proximate cause of the appearance of the misplaced stigmas. These 2 abnormal plants were crossed upon a Jone sib, o8109(1), and produced together 119 females and 60 normal males, not one of which showed any development of stigmatic calyx lobes or other female characteristics. The female o8109(1) was the one used in case VII for a number of crosses with genetic hermaphrodites, and it was also used as the seed parent in 20 crosses with males of various origin. In all of the other crosses upon this female, the males among the progenies were of the same type as the male parent used in the particular cross from which they sprang, thus showing that this female exerted no modifying influence upon the sex character of her male offspring. This makes it reasonable to conclude that the stigmatic calyx lobes were a purely somatic variation. CASE XIV THE SECOND GENERATION FROM A SOMATIC MALE Pedigree no. Result % OOTIO Sis oe a _— §09:276 OOTS0. ev ae kes 372:168 OOTS?. 66.5 33%: 268 OOTI2 85. 6s Pen 619:148 OGX0S 2s ce 492:424 OOTOG a view cee 452: 108 OOLIOs Fees wee ee 582: 336 LOM Cae es 3339: 1686 In order to make sure that the conclusions drawn from the first §eneration regarding the character of the hermaphrodites C and D, 354 BOTANICAL GAZETTE [NOVEMBER as discussed in case XII, were sound, and that there was not simply the temporary disappearance of the hermaphrodite character through some thinkable vagary of dominance in the F,, 5 males in 08125 were tested in crosses with 2 different females. The resultant progenies consisted of 333 females and 168 males. Not a single hermaphrodite appeared, thus convincingly supporting ey ow 2 SS 2 © (Somatic) L___— Lo | acsaed 2 333 168 Fic. 15.—Model pedigree for case XIV the view that the appearance of hermaphroditism in C and D was illusive, and that they were therefore only superficially like the genetic hermaphrodites A and B. These results fully justify my conclusion that the hermaphrodites of Lychnis dioica belong to two genotypes, one of which is the same as the normal male, the other different from it. Discussion and conclusions Although these data from the breeding of hermaphrodites of Lychnis dioica are presented in fourteen sections, each represenUng a somewhat different direction of attack upon the genetic problems involved, the results under the various sections are remarkably consistent. The hermaphrodites are clearly of two kinds. Those 1911] SHULL—REVERSIBLE SEX-MUTANTS 355 included under cases I-XII produced male offspring like themselves when they were used as male parents (but not when used as female parents). These have been called “genetic hermaphrodites,” to distinguish them from occasional genetic males which possess female organs as a purely somatic modification, and which I have therefore called ‘somatic hermaphrodites.”” These ‘somatic hermaphrodites”’ will be omitted from the discussion for the present. Under cases II and III it is shown that genetic hermaphrodites, of whatever origin, when self-fertilized, yield dimorphic progenies consisting of females and hermaphrodites, thus confirming the conclusions derived from the F,. This fact, together with the apparent relative ease with which males are made to exhibit the organs of both sexes, has been. accepted as conclusive evidence that the hermaphrodites (and therefore also the males) are heterozy- gous with respect to sex, and the females homozygous (SHULL 26). In this regard Lychnis dioica L. agrees with Bryonia dioica (Cor- RENS 6); with many species of Coleoptera, Orthoptera, Hemiptera, Diptera, Odonata, and perhaps also with Myriapoda and Arachnida (McCiuNne 19, WILSON 38-42, MorRGAN 20, 21, STEVENS 31-34, etc.); and with the nematode worms, Heterakis (BovERI 4) and Ascaris megalocephala (BorING 3). In man, GuyeER (16) has demonstrated that there are two types of sperms, and while the relation of one or other of these types to the type of the egg is unknown, there can hardly be a doubt that here also the female is homozygous and the male heterozygous.* Although these widely divergent groups of plants and animals agree in having homozygous females and heterozygous males, there may still be fundamental differences in the different groups, since there may be three different kinds of homozygotes, and Correspondingly different kinds of heterozygotes. This question * Heterozygous females have now been recognized in Abraxas (DONCASTER and Raynor ro, and Doncaster 8, 9), sea urchins (BALTzeR 1), canaries (DURHAM and Marryar 11), and in domestic fowl (BATESON 2, SPILLMAN 28, 29, GOODALE 12, 13, HacEpoorn 17, Peart and SURFACE 24, 25, STURTEVANT 37). GUYER (14, I5) Teports two types of sperms in both the guinea fowl and the common fowl, but these observations are out of harmony with all the genetic studies in which sex-limited characters of the Gallinaceae have been involved. The considerable difficulties encountered in the cytological studies on these species suggest the advisability of @ repetition of this work. 356 BOTANICAL GAZETTE [NOVEMBER will be discussed later in connection with the nature of the hermaphrodites. Correns (6, p. 17), with undoubted justification, maintained that the germ cells of monoecious, hermaphrodite, and dioecious species possess the tendency to develop into individuals having the distribution of sex organs characteristic of the particular genotype to which they belong; but when he likens the association of organs of both sexes in the same individual to the mosaic of red and white colors in striped flowers, and of pigmented and white spots in the coats of spotted animals, his justification becomes less obvious. Both striped flowers and spotted pelages are known from many investigations to be due to the presence or absence of a definite Mendelian gene, a so-called “spotting factor” or “pat- tern factor.” ae One of the chief aims in the arrangement of my cultures for 1910 was to test the possible existence of such a mosaic or “pat- tern factor,” H, as a proximate cause of hermaphroditism m Lychnis, and the most striking result secured is the decisive mannet in which such a possibility is denied. The hermaphrodite character is not only incapable of reaching expression in the female* (as might be expected, since the female is homozygous), but it is also as a rule not transmitted through the egg cell to the male offspring. The males in the progeny of any cross agree in their sexual type with the male parent of that cross, regardless of its antedecent history. All the assumptions and implications involved in the first section of table I, in which an independent gene H was postulated, may therefore be rejected. SI refer here only to the normal functional hermaphroditism with which this paper deals, and not the pseudo-hermaphroditism which results when females of Lychnis dioica are attacked by the smut, Ustilago violacea, as reported by STRAS- and (0) that male plants may be infected also, but such infection does not in this case result in the development of the female organs. Igrt] SHULL—REVERSIBLE SEX-MUTANTS 357 In the second section of table I the hypothetical gene H for hermaphroditism is given limitations which make it fit all the empirical results of both the first and subsequent generations; but when the significance of the limitations is taken into account, it becomes evident that there is small advantage gained by the postulation of such a gene. Indeed the only advantage lies in the fact that in case the female is a positive homozygote, it keeps open the question whether or not there is a synaptic mate of F in the normal male; for a newly arisen hermaphrodite gene (H) might conceivably become a synaptic mate of F, even though the latter had had no synaptic mate in the normal male. If the female is a neutral homozygote, that is, if the female gene F has a male gene M as its synaptic mate in the male, the hermaphrodite gene (if it exist at all) must be absolutely coupled with this male gene. In like manner, if the female is a negative homozygote FFmm, the H (if present) must be coupled with the male gene M. It is simpler, however, to assume that the hermaph- rodite determiner is a modified form of the sex gene itself, than to suppose that it is a separate gene invariably coupled with the sex gene. This conception that hermaphroditism results from a mutative change in the sex gene, or in its homologue (?), the “Y- element,” is made the basis of the last section of table I, but can apply only to those cases in which a male gene is present, or if not a male gene, then its homologue, a sexually indifferent gene which takes the place of M in the male; for if the hermaphrodite character is assumed to be due to a change in the female gene (F), as it must be if the latter has no ‘‘synaptic mate,’’ the scheme will not work. It appears to me impossible at the present time to determine whether the females of Lychnis are positive, neutral, or negative homozygotes. The facts seem to be equally well met by any of these assumptions; but the definite limitations of the hermaphro- dite character to the males makes inapplicable the extreme form of the “presence and absence” hypothesis (that is, the hypothesis of unpaired genes) unless the female is a negative homozygote With reference to a male sex gene (M). While the possibility must be kept open that this is the relationship of the sexes in Lychnis, 358 BOTANICAL GAZETTE [NOVEMBER it seems to me more probable that the female is a neutral homozy- gote (FF), the male having the formula FM, and the hermaphro- dite the formula FMy. The gradually increasing number of known instances of “spurious allelomorphism” proves that the pairing of unlike or unequal genes in the heterozygote is, if not the general condition, at least a not uncommon one. The question whether the sex genes are paired or unpaired in the heterozygote, and if unpaired, whether the female is a positive or a negative homozygote, might be settled by simple observation, if it could be known that the chromosomes are the sex determiners, as a number of recent cytological studies clearly suggest. It is not at all certain, however, whether the unequal chromosome groups in the male-producing and female-producing germ cells are active determiners or simply passive indicators of other more fundamental differences. The latter possibility is strongly empha- sized by Morcan (20), who shows that the pole to which the accessory chromosome in Phylloxera is to proceed, is already deter- mined before that chromosome has given any indication, by its own motion, to which pole it will go. This suggests that the poles of the dividing spermacyte may be sexually differentiated in ad- vance by some other factor. If the chromosomes are not the sex- determiners, but only passive indicators, the fact that they are paired or unpaired, equal or unequal, has no decisive bearing upon the question whether the female is a positive, neutral, or negative homozygote, or whether the genes are paired or unpaired in the heterozygote, for it is quite as easy to assume that the movement of the accessory chromosome or “X-element” to the female pole takes place in response to a tension caused by the absence of a positive male sex-determiner at that pole, as that it is attracted by the presence of a positive female determiner. If the “X-element” should move into the vacancy caused by the absence of the sex- determiner, the presence of the added chromosome or group of chromosomes would become the evidence of the absence of the sex gene; in other words, the female possessing the added chromo- some would be a negative homozygote. All this is highly specula- tive, and as there appears to be no way as yet to put the matter to experimental test, it seems futile to discuss further the question 1911] SHULL—REVERSIBLE SEX-MUTANTS 359 whether the female of Lychnis dioica is a positive, neutral, or negative homozygote, or whether the synaptic mate of the female gene is qualitatively male or not. ‘The matter has been considered at such length only because it is important that no unwarranted conclusions should be drawn from the configuration of the chromo- somes in any given case. There appears to be no very strong evidence at present that the chromosomes are the representatives or producers of particular Mendelian unit characters, though attempts have been made a number of times during the past decade to identify them as such. On the other hand, there is still no positive and complete demonstra- tion that the chromosomes are not the determiners of the Mendelian characters, and until this demonstration is provided, the relation of the chromosomes to the unit characters must be kept open. Whether the chromosomes are responsible directly for sex may well remain likewise an open question for the present, especially in view of the fact that in many animals, and in the few plants which have been thus far investigated, no chromosome differences have been found to differentiate the sexes. There can be no doubt of course that the sex characters are associated with chromosome differences in the considerable number of animals which have been found to present such differences, but, as we have just seen, the nature of this association is not clear. Where two types of sperms are found in the male, the one type corresponding in its chromosome complex with the single type Presented by the eggs, the inference is fully justified that such males are heterozygous and the females homozygous in respect to sex, whether one or more chromosomes be the sex-determiner, or whether these chromosomes are merely symptomatic of other fundamental differences which are the true sex-determiners; and vice versa, when two types of eggs having different chromosome §toups are found in the female, one of which agrees with the only type found in the sperms, the inference is fair that the female is heterozygous and the male homozygous in respect to sex. So consistent have been the results in those species in which both male and female germ cells have been investigated, that it has not seemed improper to assume that in any given species the one sex will have 360 BOTANICAL GAZETTE [NOVEMBER uniform germ cells, and is to be considered homozygous, if the other sex is demonstrated to have two types of germ cells.° No chromosome differences have been found in Lychnis dioica L. by STRASBURGER (36), who has studied a form of this species known in German taxonomic works as Melandrium rubrum Garcke. His careful investigation of germ cells and root tips showed 24 chromosomes to be the somatic number, one pair of these chromo- somes being notably larger than the rest, thus resembling the acces- sory chromosomes or supposed sex chromosomes of the insects. However, in Lychnis, the two members of this pair are indistinguish- able from each other in both the male and the female. The same results have been independently secured by Miss Lutz during the past year, but have not yet been published. Lychnis appears to agree, therefore, with Nezara, Oncopeltus, etc. (WILSON 39) 4°); among the Hemiptera, as in these the two types of sperms, which doubtless exist, are not visibly differentiated. STRASBURGER (36) reports also that an investigation of Bryonia dioica has not revealed the two types of sperms that might a priori have been expected. The hypothesis of unpaired determiners implies that a new Mendelian character originates by the formation of a new gene or the loss of an-old one. My interpretation of hermaphroditism in Lychnis dioica as due to an alteration in a sex gene already in existence, which alteration does not in any way change the homology of the gene in question, calls for a fundamentally different method of origin of new characters from that involved in this extreme form of the “presence and absence” hypothesis. The new genotype which arises by mutation from the old one has in this case neither more nor fewer genes than had the genotype from which it originated. The occurrence of male mutants among the offspring of my — genetic hermaphrodites appears to me to have a bearing upon this question, as to the mode of origin of new characters. Among the offspring of genetic hermaphrodites tabulated in this paper, 1 male mutants appeared, and under case XII it is shown conclusively that these are true males, and do not again give hermaphrodite offspring, except probably in the extremely small proportion given ‘As already noted, GuveEr’s (14, 15) studies on spermatogenesis in the domestic fowl and in the guinea fowl appear at present to be exceptions. 1911] SHULL—REVERSIBLE SEX-MUTANTS 361 by males not derived from a hermaphrodite family. These 11 males appeared in hermaphrodite families comprising a total of 5467 individuals, thus possibly indicating a somewhat greater coefficient of mutability than that reported for the production of hermaphrodites from normal males. It seems therefore that the Modification of the gene M (or f) into a hermaphrodite gene H, and the reversal of this modification so that a normal male gene is again produced from a hermaphrodite gene, occurs with somewhat unequal facility, but the difference is not great enough to warrant the belief that mutation in the one direction is caused by the appearance of a new, independent organ, while its reversal is due to the disappearance of that organ. It seems to me more probable that these reversible mutations are due to reversible modifications of an element or organ continuously in existence, and not to the Production of a new element or the dropping out of an old one. The change from a male to a hermaphrodite condition and the. _ Feverse are processes both striking and sudden. Perhaps they are as fundamental mutations as those observed among the oenotheras. The interpretation given here of the process of mutation in the Sex character of Lychnis seems to be available for other mutations as well. The sudden acquirement of new functions by a gene already in existence is different from the conception presented by E Vries in Die Mutationstheorie, to account for the origin of the Oenothera mutants, and is in accord with SprttMan’s “teleone hypothesis.” Sprrrman (30) is inclined to attribute the remarkable mutations in Oenothera to irregularities of mitosis, but in these Sex Mutants of Lychnis, abrupt genotypic modifications have taken place which can hardly be assigned to such irregular mitoses. One puzzling feature of the inheritance of sex in Lychnis is the fact that self-fertilized hermaphrodites produce similar ratios of females and hermaphrodites as are produced when unrelated females are fertilized by sperms from hermaphrodites. Since it is obvious that the two types of offspring are due to the heterozygous character of the male, we are led to the conclusion that even though the hermaphrodite individual is heterozygous in respect to sex, its egg cells? are of a single type like those of the normal female * Perhaps I should say “its successful egg cells.” 362 BOTANICAL GAZETTE [NOVEMBER and carry only the female tendency, while its sperm cells are of two types, one of which has the same sex character as the egg cells, the other bearing the hermaphrodite condition. In my preliminary paper, it was suggested that those eggs may fail to develop which lack the female gene F, or which possess the male gene M; or that in case the female is a negative homozygote, there might be an extrusion of the male gene during oogenesis. As there are no visible cytological differences between the females and the hermaph- rodites, it may not be possible to decide these questions. The relatively small number of seeds in the hermaphrodites, as com- pared with the females, appears to be favorable to a selective elim- ination of male-bearing eggs. Another explanation seems possible. A segregation of the female and male genes may conceivably take place earlier than the time at which the germ cells are formed, though it must be admitted that there is little evidence at present that such early segregations regularly take place in any plant or animal. Such a suggestion has been made by BATESON (2, P. 159); however, in the effort to account for certain interesting instances of coupling. If a segregation of female and hermaphrodite genes could be assumed to take place as early as the formation of a certain primordial cell from which the entire reproductive tissue of the ovary develops, so that the ovules are supplied only with the female genes, the observed uniformity of the egg cells would result. If segregation may take place thus before the spermacytes are devel- oped, this might also offer an explanation of the exceedingly variable sex ratios which occur in Lychnis, for an unequally rapid develop- ment of tissues derived from female-bearing cells and male-bearing cells, from the moment of segregation until the spermacytes are produced, would give an unequal number of female-bearing and male-bearing sperms, and variability in this process would produce irregular ratios. I place no stress upon this hypothesis, howevet; and am inclined to look for an explanation of the observed phenom- ena in some sort of selective elimination. There remains to be considered the relation of the somatic hermaphrodites to the problems of sex determination. The results under cases XIII and XIV show that the hermaphrodite * They are known to take place occasionally in the production of bud sports: Igtt] SHULL—REVERSIBLE SEX-MUTANTS 363 character of these plants was purely superficial and did not affect the germ cells in any recognizable manner. The only bearing these plants have upon the question of sex determination, I think, is in the evidence they give that genetically normal males may be induced in some unknown way to exhibit female characters. When the male is interpreted as a Mendelian heterozygote in respect to the sex-producing gene, the occurrence of such a somatic modifica- tion has the appearance of a simple case of imperfect dominance, such as has been noted not infrequently in other Mendelian hetero- zygotes. However, the development of male organs (non-func- tional) in the supposedly homozygous female, when the latter is attacked by the smut (Ustilago violacea), gives support to the _ View held by SrraspurcER (36), that not only the heterozygous sex but both sexes contain in some degree the elements of the Opposite sex or the capacity to react in the sexually opposite Manner. This fact may perhaps indicate that sex is a more fundamental condition than might be inferred from the frequency with which it behaves as a Mendelian unit character. MorGAN (23) suggests a way in which the appearance of the organs or characters of one sex in individuals of the opposite sex may be explained in harmony with the Mendelian interpretation of sex determination. He assumes that there may be present, underlying the female sex gene, a male element with respect to which all individuals of both sexes are homozygous. This he indicates by introducing m into all of his sex formulae. In keeping with com- mon usage among geneticists, he should have used M, since he intends to denote the presence of maleness. While recognizing the aptness of this suggestion in removing Some of the difficulties in the way of a general application of the Mendelian explanation of sex, I am inclined to the view that the Mendelian nature of sex is of secondary rather than of primary consequence. May not maleness and femaleness be thought of as alternative states, which can be crudely analogized with the acidity and alkalinity of chemical solutions? Just as solutions may be made acid or alkaline in different ways, either by qualita- tive or by quantitative additions, subtractions, or substitutions, or by a combination of qualitative and quantitative changes, it 364 BOTANICAL GAZETTE [NOVEMBER is conceivable that the alternative sexual types may be determined in different cases by very different methods, some qualitative, some quantitative, and others both qualitative and quantitative. In some species the sexes appear to represent a much more strongly polarized (?) condition than in other species, and a transition from the characters of the one sex to those of the other is attained only with the greatest rarity, if at all; while in other species the sex conditions may be so nearly balanced or neutral that individuals are not so absolutely determined in their sex relations by their genotypic nature, thus resulting in ever-sporting varieties in respect to sex, such as CorrENS (7) has found in Plantago lanceo- ata With such a conception of sex, it also appears probable that sex may be influenced sometimes by external factors as well as : by internal ones, and in this case the preponderance of one sex over the other, which has been observed in many animals and plants, need not be attributed alone to a selective disorganization of germ cells, a selective fertilization, or a selective death rate, but might conceivably be controlled to a certain extent by environ- mental conditions acting at some particular “sensitive period” in the ontogeny of the organism in question. However this may be, there is little or no evidence at present that such environmental influences on sex can be more than relatively slight in the case of dioecious plants and animals. In such organisms recent genetic and cytological studies prove conclusively that sex is generally determined by the genotypic nature of the individual. Summary The hermaphrodites of Lychnis dioica are modified males. They are of two kinds, which are here distinguished as “genetic” and “somatic” hermaphrodites. When the genetic hermaphrodites are used as pollen parents, either when self-fertilized or in crosses with females, their pros" enies consist of females and hermaphrodites. When they are use as pistil parents, and fertilized by normal males, they produce females and normal males. Somatic hermaphrodites may be externally indistinguishable tort) SHULL—REVERSIBLE SEX-MUTANTS 365 from the genetic hermaphrodites, but when used as pollen parents they produce no hermaphrodite offspring, but only females and normal males. The fact that males can be modified so as to produce functional organs of both sexes, indicates that they are sex heterozygotes, and the production of both females and hermaphrodites by self- fertilized hermaphrodites strongly supports the same interpretation. The hermaphrodite character can neither find expression in the females, nor can it be transmitted by their eggs to the male offspring. Consequently it is not determined by an independent gene, H, but by a modification of the male sex gene, M, or of the “synaptic mate”’ of the female gene, F. If the males and hermaphrodites are heterozygous, it follows that the females are homozygous; but this does not offer an ulti- mate solution to the relationship between females and males, since there may be several different kinds of homozygotes and heterozygotes. As applied to the relation of the sexes, these may be indicated by the following formulae: (a) The female may be a “positive” homozygote; then FF=9, Ff{f=2, Ff” or FH=%. (b) If the female is a “negative” homozygote, FFmm=9, FFMm=é, FFMym=%. (c) When the female is a “neutral” homozygote, FF=9, FM=2, FMqg=%. In each of these formulae the subscript H is intended to represent a modification of the gene to whose symbol it is appended, such that the male is changed to a her- maphrodite. Which of these formulae correctly represents the con- dition in Lychnis can not be determined, but the modified gene Which results in hermaphroditism is allelomorphic to F unless the female is a negative homozygote. Among the offspring of genetic hermaphrodites were a small number of male mutants (11 in 5467), which on breeding proved to be normal males. The occurrence of these male mutants indi- cates that the modification to the hermaphrodite condition, and back again to the male condition, occurs with but slightly unequal facility, and this circumstance is believed to favor the view that mutation in this case depends upon reversible modifications of Some permanent element or organ, rather than upon the origina- tion of a new unit, and its disappearance. This interpretation 366 BOTANICAL GAZETTE [NOVEMBER bears both upon the nature of mutation and upon the real signifi- cance of the “‘presence and absence” hypothesis. STRASBURGER has shown that females of Lychnis dioica attacked by Ustilago violacea become pseudo-hermaphrodites through the production of stamens, which however are non-functional, owing to the fact that the smut produces its spores in the anthers. This seems to justify his conclusion that each sex possesses some of the potentialities of the opposite sex. The view is expressed that the sexes represent alternative states which in different species may be attained in various ways, through either quantitative or qualitative changes, additions, subtractions, substitutions, or transformations, and that in some instances the action of environment may prove effective in deter- mining which of these states shall find expression. Nearly all the recent investigations indicate, however, that sex is at least predominantly dependent upon the genotypic nature of the indi- vidual. CARNEGIE STATION FOR EXPERIMENTAL EVOLUTION Cotp Sprinc Harpor, N.Y LITERATURE CITED 1. Batrzer, F., Ueber die Grésse und Form der Chromosomen bei Seeigel- eiern. Verhand. Deutsch. Zool. Gesells. 1908. 2. Bateson, W., Mendel’s principles of heredity. pp. xiv+396. Cambridge: University Press. 1909. Borine, Atice M., A small chromosome in Ascaris megalocephala. Arch. 4 Zellf. 47:120-131. pl. 1. 4. Boveri, T., Ueber “ Be techs cen” bei Nematoden. Arch. f. Zellf. 4132-141. figs. 2. 1909. 5. Castie, W.E., A Mendelian view of sex heredity. Science N.S. 29*395- 400. 1909. 6. Correns, C., Die Bestimmung und Vererbung des pees nach neuen Verbuchens mit hdheren Pflanzen. pp. vii+8r. figs. super Gebr. Borntraeger. 1907. , Die Rolle der mannlichen Keimzellen bei der Geschlechtsbestim- mung ier gynodioecischen Pflanzen. Ber. Deutsch. Bot. Gesells. 26a: 6-701. 1908 : 8. Doncaster, L., Sex inheritance in the moth Abraxas grossulariata and its var. lacticolor. Report Evol. Comm. IV. pp. 53-37. 1908. 7. 1911] SHULL—REVERSIBLE SEX-MUTANTS 367 9. Doncaster, L., Recent work on the determination of sex. Sci. Prog. NO. 13. Pp. gO-104. Ig09. 10. —_——,, and Raynor, G. H., Breeding experiments with Lepidoptera. Proc. Zool. Soc. London 1:125. 1906. 11. Durnam, F. M., and Marryat, D. C. E., Inheritance of sex in canaries. Report Evol. Comm. IV. pp. 57-60. 1908. 12, GoopaLe, H. D., Sex and its relation to the barring factor in poultry. Science N.S. 29: 1004, 1005. 1909. Breeding experiments in poultry. Proc. Soc. Exp. Biol. Med. 14. Guyer, M. F., The spermatogenesis of the eng guinea (Numida meleagris Doiy. Anat. Anz. 34:502-513. pls. 2. 9. 15. ———,, The spermatogenesis of the domestic o45 (Gallus gallus Dom.). Anat. Anz, 34:573-580. pls. 2. 1900. , Accessory chromosomes in man. Biol. Bull. 19:219-234. i. 1. 16. IQIo, ; 17. HaGEpoorn, A. L., Mendelian inheritance of sex. Arch. f. Entwick. Mech. 2831-34. 1909. 18. Horsr, C. C., Mendelian characters in plants and animals. Report 3d Internat. Conf. on Genetics. Jour. Roy. Hort. Soc. pp. 114-128. 1906. 19. McCune, C. E., The accessory ehitonjoecme “sex determinant? Biol. Bull. 3: 43-84. fon. 20. Morcan, T. H., A biological and cytological study of sex determination in phylloxerans ad aphids. Jour. Exp. Zool. 7:239-352. pl. I. 1900. 21. , Sex limited inheritance in Drosophila. Science N.S. 32:120-122. IgIo. 22. ———. Chromosomes and heredity. Amer. Nat. 44:449-496. I9gIo. 23. ———, The application of the conception of pure lines to sex-limited inheritance and to sexual dimorphism. Amer. Nat. 45:65-78. rgrt. 24. Peart R., and SurFAcE, F. M., On the inheritance of the barred color Pattern in poultry. Arch. Entwick. Mech. 30:45-61. pls. 2. fig. I. 1910. , Further data regarding the sex-limited inheritance of the barred color pattern in poultry. Science N.S. 32:870-874. 1910. 26. SuuLt, G. H., Inheritance of sex in Lychnis. Bot. Gaz. 49:110-125. Sigs. 2. Igto. 27. ———, The “presence and absence” hypothesis. Amer. Nat. 43:410- 25. 419. I909. 28. Spruman, W. J., Barring in barred Plymouth Rocks. Poultry 5:7, 8 1909. 29. , Spurious allelomorphism: results of recent investigations. Amer. Nat. 42:610-615. 19009. , Mendelian phenomena without De Vriesian theory. Amer. Nat. 44:214~228. 1910. 30, 368 BOTANICAL GAZETTE [NOVEMBER 31. STEVENS, N. M., Studies in spermatogenesis with special reference to the “accessory chromosome.” Pub. 36, Carnegie Institution of Washington. Tone. 32. ———,, Studies in spermatogenesis. II. A comparative study of the boo cicciiosomes in certain species of Coleoptera, Hemiptera, ve Lepidoptera, with special reference to sex determination. Pub. Carnegie Institution of Washington. 1906. , A study of the germ cells of certain Diptera with reference to the aeedchieanes and the phenomena of synapsis. Jour. Exp. L 5*359-374. pls. 4. 1908. ——, The chromosomes in Diabrotica vittata; Diabrotica soror, and © Dibtiolics 12-punctata. Jour. Exp. Zool. 5:453-470. pls. 3. 1908. 35- STRASBURGER, E., Versuche mit dioicischen Pflanzen in piaiaet auf ae Biol. Centralbl. 20:657-665, 689-698, 721-731; 753-785. figs. 5. , Ueber Si idstetinnccd Ursachen. Jahrb. Wiss. Bot. 48:427-520. pls. 2. 1910. 37- STURTEVANT, A. H., Another sex-limited character in fowls. Science N.S. 33: 337-338. 1911. 38. Wutson, E. B., Studies on chromosomes. II. The paired microchro- mosomes, idiochromosomes, and uence chromosomes in Hemiptera. Jour. Exp. Zool. 2:507-545. figs. 4. 1905. 39. , Studies on chromosomes. on The sexual differences of the chromosome groups in Hemiptera, with some considerations on the deter- mination and inheritance of sex. Jour. Exp. Zool. 3:1-40. figs. 6. 1906. 40. ————, Studies on chromosomes. IV. The “accessory” chromosome in Ses niicies and Pyrrochoris, with a comparative review of the types of sexual differences of the chromosome groups. Jour. Exp. Zool. 6: 69-99- pls. 2. fig. 1. 1900. 41. ———,, Recent researches on the es and heredity of sex. Sclence N.S: 29: 53-70. 1900. e chromosomes in relation to the determination of SeX Science Pig no. 16, pp. 570-592. figs. 3. I9gIo. 36. 42. REPRODUCTION BY LAYERING AMONG CONIFERS CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 149 WILLIAM S. COOPER (WITH ONE FIGURE) Many types of plants multiply more or less by layering, or may be made to do so by artificial means. The fact seems not to be well known that various conifers, particularly members of the genera Picea and Abies, possess this power and multiply by it to some extent. Having by accident discovered a case of layering in the balsam fir (Abies balsamea [L.] Mill.) during the course of ecological work on Isle Royale, Lake Superior, I found that the habit was a factor of considerable importance in the dynamics of the forest. Investigation into the literature of the subject brought to light a few scattered references to layering of coniferous trees, which are noted below. It is not probable that the list is exhaustive. I. Literature The earliest description that was found was contained in Lov- DON’S Arboretum et Fruticetum Britannicum (8), vol. IV, pp. 2297- 2298. The author quotes Mr. James M’Naps in The Gardener's Magazine as follows: _ From the pendent habit of the lower branches of the spruce (Picea excelsa Link) some curious anomalies are occasionally found in its habit of growth. The shoots next the ground, when they have attained a considerable length, naturally rest on the soil at their extremities; and the soil being kept moist by the shade of the branches, these often root into it; and the points of their shoots taking a vertical direction, a series of new trees are formed in a circle round the old tree. A particular specimen, growing in Scotland, is described thus: Many natural layers from the trunk and from the primary substems have taken root, so as to form a double series of young trees in two concentric circles round the parent trunk. A little farther on is the following: That portion of the branch which is between the trunk of the original tree and the part where it roots into the ground, and which is sometimes several feet in length, rarely i in diameter after its extremity has rooted... . . 369] [Botanical Gazette, vol. 52 37° BOTANICAL GAZETTE [NOVEMBER The branches proceeding from the primary substems have also branches, equally healthy with themselves, proceeding from them, and with every appear- ance of their producing others. . .. . e primary substems, which constitute the inner concentric circle of young trees, vary from 8 feet to 25 feet in height; and the secondary substems, which form the trees of the outer circle, are from 4 feet to 10 feet high. There are upward of thirty rooted stems surrounding the mother tree, and 30 feet is the greatest diameter of the space covered by stoloniferous branches; though in one case a secondary layer has reached as far as 18 feet from the main trunk. Loupon also mentions cases of abundant layering in Abies nigra (Picea mariana [Mill.] BSP.). UNZE (7) also refers to M’Nas’s observations and concludes from these and other cases that ‘Coniferae, especially the Abie- tineae, possess widely extended power of root formation and are able to send out rooting shoots.” KiHLMAN (6) notes that Picea excelsa growing at the arctic tree line in Lapland spreads extensively by layering. He describes the occurrence of the habit as follows. The lowest branches often have roots, and from their tips new erect shoots develop, which become treelike in form and come to lead independent lives; from this results a complex of shoots and small trees of various ages, which is very sharply bounded, and which often arises from a single parent. Such a group, 4 meters in diameter, included 42 stems more than 4 cm. thick, besides numerous smaller ones. The age of such a centrifugally spreading group of spruces may almost be unlimited. He distinguishes two habit varieties of Pues excelsa. One possesses a tall cylindrical crown, often extending to the ground, the lower branches seldom rooting, and the life of the individual thus ending with the death of the main trunk. The other variety, characteristic of the region of the northern limit of the spruce, is low and scrubby, and layers abundantly as described above. Curist (2) refers to layering in Picea excelsa as of rare occur rence, and names such forms Picea excelsa forma stolonifera. GOEBEL (5) mentions cases of layering in Picea excelsa, P. nigra; and Abies sibirica. ScHROTER (11) describes and illustrates something very similar in the case of Pinus montana in the timberline belt of the Alps- Tort] COOPER—LAYERING AMONG CONIFERS 371 He speaks of “horizontal snakelike branches crawling over the ground, ascending or erect at the ends,” but does not state, nor do his figures show, that these branches take root. According to Mayr (9) all deciduous trees and conifers are able to produce roots when branches or weak stems are bent down and placed in contact with the ground for a time. He mentions the following genera as among those that have been observed to reproduce by layering: Abies, Picea, Pinus, Larix, Pseudotsuga, Chamaecy paris, Cryptomeria. Micuta (10) briefly notes the habit, and gives an illustration of a spruce (Picea excelsa) surrounded by a circle of young trees developed from layered branches. VOGTHERR (13) speaks of the habit as occurring frequently, though often overlooked, and states that it is commonest in moist habitats in northern latitudes and in mountain regions. Reproduction by layering among conifers has been reported in America, so far as I have been able to discover, in two species only, both of the genus Abies. SuDWorTH (12) in discussing the reproduction of the alpine fir (Abies lasiocarpa [Hook.] Nuttall) says (p. 111): ‘Occasionally at high elevations branches lying on ground take root (layer), from which, however, reproduction is probably rare.” In Silvical Leaflet (4) of the Forest Service, devoted to Abies lasiocarpa, is the following paragraph: Alpine fir frequently exhibits a tendency to reproduce by layering. The lower branches, which are procumbent, become covered with earth, roots are Produced, and the branches increase in size and assume an upward curve. It is doubtful, however, if the tree ever actually reproduces itself in this manner. The tendency becomes more apparent with increasing altitude, the main trunk tte shorter, while the layered branches form a saucer-like whorl at its ase. CLEMENTS (3), speaking of the same species in the Colorado mountains, states that “all the young firs examined had started by layering from the lower branches of parent trees.” Concerning the eastern balsam fir (Abies balsamea [L.] Mill.) I have found but one notice of the habit. CarrreNDEN (1) in discussing the timberline trees of the White Mountains says: - 372 BOTANICAL GAZETTE [NOVEMBER Balsam, at such elevations, rarely matures its seed, reproduction being de- pendent on seed blown up from below and on the layering of the trees them- selves. Branches so layered are often found growing as independent trees, the connecting branch having decayed. The rooting always proceeds from rmant buds. Prostrate balsam occurs at an altitude of 5500 feet on the Presidential Range, where it reproduces almost entirely by layering. At an elevation of 4900 feet cones are borne sparingly, but even here reproduction by layering exists. II. Layering as observed on Isle Royale, Lake Superior Upon Isle Royale the layering habit manifests itself as follows. In the forest one frequently comes upon small groups of young balsams, often of about half a dozen individuals of various sizes. These upon superficial inspection would easily pass for a cluster of seedlings, but if the group be carefully dug up, all the young trees will be found to be connected with each other a little below the surface of the ground. The way in which the layering comes about was found to be as follows. The lower branches of the balsam droop more or less, and the middle portion of such a branch fre- quently becomes covered with moss, litter, and humus. If the point of origin of the branch is very close to the ground, the connec- tion soon becomes entirely concealed; this seems to be the case more often than otherwise. The covered portion now produces roots abundantly, and the tip becomes erect, loses its dorsiventral character, takes on radial symmetry, and is to all appearances @ perfect miniature tree. _ Layering may take place at any stage in the life of the tree. Sometimes the layered branch may be only a few years younget than the parent and not very perceptibly smaller, showing that it must have developed from one of the very earliest branches. Mere seedlings were sometimes seen with layered branches about as large as the parent. The daughter trees often produce a second generation, and it is in this way that the groups of apparently independent saplings come into existence. On the other hand, cases were found where a mature tree was layering through branches that had their points of origin a number of decimeters above the ground. Several of the lower branches of a mature tree may layer, producing a circle of young trees around the parent, and numerous 1911] COOPER—LAYVERING AMONG CONIFERS 373 Cases were found in which the layered branches themselves had given rise to secondary groups, the connection with the original tree being still maintained. There is abundant evidence that in many cases the layered branches become independent trees by the decay of the connecting Portions. In fig. x it may be seen that the layered branch near its Point of origin is extremely slender, while in the region where the roots have developed and in the subaerial portion it is thick. The _ transition from thin to thick is frequently very abrupt. This Points toward the conclusion that the young tree is deriving by far the greater amount of its sustenance from its own root system, and that if the connection should be broken it would be entirely able to care for itself. The underground portion was often so weak that in spite of the greatest care it was severed in the process of uprooting. In many cases also the decumbent bases of independent young balsams indicate that they once had a horizontal connection With some neighboring tree (see a in fig. 1). Some examples will make clear the various forms which the habit of layering takes. 1. A very typical case is seen in fig. 1. The oldest stem shown in the photograph is at r (all but the base has been removed for the Sake of clearness). That this is itself a layered branch of a still older tree is indicated by the long rhizome-like structure (a) extend- ing horizontally toward the left. The character of the well formed young tree 2 as a layered branch of 7 is evident. Branch 2 is one meter high. Branch 3 is connected with 2 by way of c, and has itself given rise to 4; the latter finally has produced 5. There are thus represented five generations of upright stems produced by Ttepeated branching and layering. Each except the youngest pos- Sesses a well developed root system of its own, and in every case except the last the horizontal connecting stem behind the region of vigorous rooting has remained practically without further development. The constriction where b joins 1 is especially evi- dent. Branch 5 receives all its nourishment from 4, and the latter Probably still derives much from 3. 2. A balsam 2 meters high, which had died very recently at the age of 46 years, itself apparently a layered branch, had given rise 374 BOTANICAL GAZETTE [NOVEMBER through a lower branch to a young tree 7.5 dm. high, 24 years old, 2.5 dm. distant from the parent. This daughter tree was found to have produced four smaller ones, 1.5-6 dm. in height, with ages ranging from 16 to 22 years. 3. That the habit may show itself even in large and mature individuals is proved by the following case. This tree, a balsam es 7° aRyS EAN a eese Fs Fic, 1.—An example of layering as it commonly occurs on Isle Royale, Lake Guteibie: Abies balsamea. 1.5 dm. in diameter and 85 years old, had given rise to a daughter tree through a layered branch which started 7.5 dm. above the ground. The outer portion of this branch was soil covered and had well developed roots. At a distance of one meter from the parent it became a symmetrical tree 1. 3m. high. The same large branch had also produced two smaller trees by the layering of secondary branches. tort] COOPER—LAYERING AMONG CONIFERS 375 4. A balsam growing in a large rock crevice at the forest edge On an exposed shore had several layered branches, erect at tip, through the soil at the general level of the ground. Several similar branches, at about the same elevation but in line with the crevice, descended into it somewhat, but their ends were erect, radially symmetrical, and perfectly treelike. Since the crevice was a foot wide and contained no soil, no roots were formed in this case, and these branches remained entirely dependent upon the tree. Aside from the balsam, layering was less frequently observed in every one of the coniferous trees that occur upon Isle Royale. It was fairly common in the case of the black spruce, perhaps being favored by the pronounced droop of the lower branches of that species. The black spruce occurs sparingly in the upland forest, and in this habitat the layered branches were identical in behavior with those of the balsam. Black spruces and tamaracks growing in bogs were found to layer abundantly through the rapidly grow- ing sphagnum. Specimens of white spruce were found upon nearly bare rocks, whose lowest branches, covered with a thin mantle of humus, had developed the layering habit to such an extent that the parent had become entirely surrounded by a group of daughter trees. Similar groups were seen in the case of arbor vitae growing IN a river swamp. Ill. Conclusions from data presented From the material here presented we gather that the habit of natural layering among coniferous trees is common and widely distributed, though its importance appears to have been generally overlooked, at least in this country; that it is particularly character- istic of the closely related genera Picea and Abies, but is found in many other genera, among which are Larix, Thuja, Pinus, Pseudo- tsuga, Chamaecyparis, and Cryptomeria; that it is most prominent in northern and mountain regions, and that it occurs more fre- quently and attains more striking development with increasing latitude and altitude; that its best development is found at the extreme limit of the forest—the arctic tree line and the mountain timberline. The general region of its occurrence is practically that of conifer 376 BOTANICAL GAZETTE [NOVEMBER dominance; its increased development in high latitudes and alti- tudes is not so easily explained. VoGTHERR (13) correlates the layering tendency with a moist habitat, made possible by the low evaporation rate in northern and mountain forests, and it is doubt- less true that moisture and absence of light are the factors that stimulate the buried portions of the branch to root production. But cases were noted (see example 4 above, and also SCHROTER 11), in which, although the end of the branch became erect and treelike, no portion was buried, and therefore no roots were formed. In other cases trees with layered branches were found growing in xerophytic situations upon the exposed rocky shores of Lake Superior. Timberline conditions, too, more often than not, are xerophytic in the extreme. The connection with a moist habitat thus seems not to be an essential one. In explanation of the striking cases of layering reported from the tree line in various regions (circles and double circles of daughter trees surrounding the parent), it may be noted that in such localities the forest is open, and the trees therefore, on account of abundance of light, - are clothed with living branches to the ground. Moreover, they are as a rule short, bushy, and branchy, and the low crown tends to spread horizontally rather than to increase in height. Just such conditions as are found here (numerous healthy branches close to the ground) are those which would apparently most favor the appearance of the layering habit. In the endeavor to solve the problem, however, the meagerness of the data should be borne in mind. It may be that more extended and careful observation would prove that the habit is as common at low latitudes and alti- tudes as at high. Possibly the greater number of reports from arctic and alpine regions is due to the fact that the phenomenon is most easily observed there, or that individual cases of more striking appearance have been found. On Isle Royale, though the habit was exceedingly common, no such remarkable examples were dis- covered as those reported by Loupon and KimLMAN. IV. Ecological importance of layering The habit of layering, in regions where it occurs, must be included as an important factor in any investigation of forest torr] COOPER—LAYERING AMONG CONIFERS 377 dynamics. For example, in the climax forest of Isle Royale there 1S an appearance of thick reproduction, with a great preponderance of balsam in the young growth. Upon superficial examination one would conclude that reproduction by seed is taking place at a tremendous rate. Careful investigation reveals that a large pro- Portion of the apparent seedlings are in reality merely layered branches, some of them having originated from mature trees, and Many others being groups of connected shoots which have started from a single true seedling. The same situation was found by Clements (3) in Colorado. It is evident that the effectiveness of this method of reproduction will have an important bearing upon the course of the succession in the forest. The habit is of special importance in the region of timberline, where, according to authors quoted above, it is sometimes almost the only method of repro- duction. V. Physiological bearing There are also physiological problems involved in the phe- nomena of layering in this group of plants, which cannot at present be Satisfactorily settled. These problems relate to the theories of orthotropism and plagiotropism and their mutual relations. The Whole subject is at the theoretical stage, without adequate evidence mM support of any of the various hypotheses. In the process of layering, the rooting (when it occurs) is simple enough as a response to moisture and absence of light. The change from dorsiventral to radial symmetry is to be expected as a result of the tip becoming erect, being an adjustment to changed light relations. The change in direction of growth from horizontal to erect is the part that is difficult to explain. It is bound up with the agencies which cause lateral shoots, ordinarily plagiotropic, to become orthotropic when the terminal shoot is removed or damaged. In the process of layer- ing, it should be noted, this change takes place without antecedent removal of the main shoot. The case is thus somewhat different, but the same factors doubtless govern it. In the present state of knowledge relating to orthotropism, plagiotropism, and correlation, it will be useless to continue the discussion at length. One point however seems to be important enough in its bearing upon the 378 BOTANICAL GAZETTE [NOVEMBER physiological side of the question to justify a few words in conclu- sion. GOEBEL (5, chapter iii), to explain the replacement of the terminal by a lateral shoot, offers the theory that the change in direction of growth of the lateral comes about because of changed conditions of nourishment. He thinks that the main transpiration current, which ordinarily goes to the terminal shoot where growth is most vigorous, is deflected when the terminal shoot is removed, and passes into the uppermost lateral. The great increase in nutri- tion acts as a stimulus, causing the lateral shoot to become erect. He describes several cases of layering among conifers, and attributes the change in direction of growth of the layered branch to the same factor. In this case the increased amount of food materials which acts as the stimulus is furnished through the agency of the newly formed root system. This theory would fit most of the cases of layering which have been described, but in one example which came under my observation on Isle Royale (no. 4 above) the change of direction of growth took place with absolutely no root formation. The same is probably true of those described by ScHROTER (11). Here are cases, therefore, where GOEBEL’s explanation certainly does not hold, and so far as this bit of evidence goes, it throws - doubt upon his theory as a whole. THE UNIVERSITY OF CHICAGO LITERATURE CITED 1. CHITTENDEN, A. K., Forest conditions of — New Hampshire. U.S. Dept. Agric., Been of Forestry, Bull. 55. 1905. 2. Curist, H., Schweiz. Zeitschr. fiir Forstwesen, seb, p. 2 258 (see VOGTHERR 13). 3- CLements, F. E., The life history of lodgepole burn forests. U.S. Dept. 4. Forest Service, U.S. Dept. Agric., The subalpine fir. Silvical Leaflet 1. 5- GOEBEL, K., Einleitung in die experimentelle Morphologie der Pflanzen. Leipzig u. Berlin. 1908. 6. Kiaiman, A. O., Pflanzenbiologische — aus Russisch Lappland. Acta Soc. Fauna et Flora Fenn. 5: n. 3. 7- Kunze, G., Einige Falle von Pieiatons dee Nebenaxen in Hauptaxen bei den Abilis: Flora 9:145-151. 1851. 8. Loupon, J. C., Arboretum et Fruticetum Britannicum. London. 1844- tg1t] COOPER—LAYERING AMONG CONIFERS 379 9. Mayr, Heryricu, Waldbau auf naturgesetzlicher Grundlage. Berlin. 1900. 10. MicuLa, W., Biologie der Pflanzen. Leipzig. 1909. rt. Soratiree. C. , Das Pflanzenleben der Alpen. Ziirich. 1904-190 12. SupworrH, G. B., Forest trees of the Pacific slope. U.S. sane Agric., Forest Service. $505. - VoGTHERR, J., Altes und Neues tiber Adventivwurzeln. Forstwiss. Centralbl. 305-316. 1910. he w THE ENDOSPERM OF ANGIOSPERMS CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 150 JoHn M. COULTER : In a recent analysis of all the available testimony in reference to the morphological nature of the endosperm of angiosperms, it seemed clear that certain conclusions might be reached, and the purpose of the present paper is to state them. It has been assumed that the endosperm must be either gameto- phytic tissue or sporophytic tissue, and the arguments for each view are familiar. The perplexity has arisen chiefly from the feeling that gametophyte and sporophyte must be subject to rigid definition. When definitions become rigid, ideas become rigid also, and nature is always playing havoc with rigidity. If gameto- phytes and sporophytes are defined as x and 2x structures, respec- tively, straightway x sporophytes and 2x gametophytes are dis- covered. If sporophytes are defined as structures produced by fertilized eggs, the definition is contradicted by numerous sporo- phytes that are not the product of fertilization. In this way, every criterion suggested has found its contradiction. It is becoming evident that definitions must be elastic and not rigid, and that general situations rather than definite categories must determine conclusions. We have moved so far beyond the rigid categories of the days of metamorphosis, that it is surprising to find an equal rigidity in the days of alternation of generations. Without citing an extensive and familiar literature, attention may be called to the various claims that have been made as to the morphological nature of the endosperm of angiosperms. Ever since the comparative morphology of the vascular groups was uncovered by HormetsreEr, belief has been general that the endosperm of angiosperms is gametophytic tissue which develops after fertilization. It was easy, even in the days of HoFMEISTER, and much more so now, to obtain from gymnosperms what seems to be abundant confirmation of this claim. Throughout that group there is a distinct tendency to differentiate eggs earlier and earlier Botanical Gazette, vol. 51] ‘ [380 & Igrt] COULTER—ENDOSPERM OF ANGIOSPERMS 381 in the ontogeny of the gametophyte. When this differentiation occurs along with the first appearance of tissue after the free nuclear Stage (as in 7, orreya), it is clear that the great bulk of endosperm tissue is developed after fertilization. When the differentiation occurs during the free nuclear stage (as in Gnetum), it is clear that all the endosperm tissue is developed after fertilization. It was very easy, therefore, to see in the endosperm of angiosperms only belated gametophytic tissue. When the relation of the polar fusion to endosperm formation began to be appreciated, LE Monnier (1887) suggested that this fusion is a sexual act, and that therefore the endosperm is sporo- phytic. This would mean that the embryo and endosperm are twin sporophytes, the latter for some reason not developing the organization of an embryo. This explanation of the polar fusion does not seem to have met with much approval. It is important to note, however, that lack of approval was probably due to the fact that there had developed already a considerable knowledge of the great freedom of nuclear fusions within the embryo sac and within the endosperm. Clearly all such fusions could not be sexual. With the discovery of “double fertilization,” the endosperm Problem became conspicuous. One of the nuclei that enters into the triple fusion is plainly a male nucleus; one of the polar nuclei is sister to the egg nucleus, and this was taken to indicate its sexual character; the other polar nucleus has been regarded as vegetative in character. The fusion of an undoubted male cell and an assumed egg was regarded as an act of fertilization, and the product of such a fusion must be a sporophyte. This con- clusion as to the nature of the endosperm is inevitable if the triple fusion is to be regarded as involving a sexual fusion. If the endosperm is a sporophyte, it must be explained why it does not become organized as an embryo, but remains as formless tissue. Miss SARGANT (1900) offered a very ingenious explanation, effectively supported by what seemed to be confirmatory evidence. ccording to this explanation, the endosperm remains a formless mass of tissue (a ‘“‘monster’’) because a vegetative nucleus enters into the fusion and interferes with the legitimate result. This view is attractive, but hardly explains the increasing number of 382 BOTANICAL GAZETTE [NOVEMBER cases in which the so-called vegetative nucleus does not enter into the fusion, and still the product is only endosperm. STRASBURGER analyzed the situation, and held to the original interpretation of the endosperm as gametophytic tissue, on the plea that there are two aspects of fertilization, one being fertiliza- tion as a stimulus to growth, the other being fertilization as a transmission of hereditary characters. These two aspects he designated respectively vegetative fertilization and generative fertilization. He saw in the result of the triple fusion only a stimulus to growth, resulting merely in tissue, and not a trans- mission of hereditary characters, which would express itself in an organization. Unfortunately for this view, all the phenomena of xenia are against it, for in such cases it is quite evident that char- acters of the pollen parent are transmitted to the endosperm by the male nucleus that enters into the triple fusion, but of course there is no sporophytic organization. Furthermore, the cytological test for the two generations breaks down in this case, as it had in cases of apogamy and apos- pory, for the seinen number of chromosomes, in case triple fusion has occurred, is neither x nor 2x, but at least 3x. To speak of 3x gametophytic tissue is to use some other test than the number of chromosomes. It must not be understood that this in any way affects the general contrast between gametophytes and sporophytes on the basis of chromosome numbers. A generation that follows a reduction division is of necessity an x generation; and one that follows fertilization is a 2x generation. But when the reduction division or fertilization does not occur, and still another generation follows, the chromosomes of that generation must become unusual in number, following an unusual situation. It will be helpful to consider the cases of endosperm formation that do not involve triple fusion. This will enable us to recognize the fact that the origin of endosperm is not necessarily related to the triple fusion, and that we have in endosperm a constant product arising from variable antecedents. It is simple to put such cases into two categories: (r) multiple fusions, and (2) no triple fusion. (1) The well-known case of Peperomia may represent the category of multiple fusions. In the fusion of 8-14 nuclei to form 1911] COULTER—ENDOSPERM OF ANGIOSPERMS 383 the “primary endosperm nucleus,’’ we observe an act too miscel- laneous to represent anything so definite as fertilization. More- Over, we obtain positive evidence that in the embryo sac there is some condition that favors nuclear fusions, quite apart from what may be called sex attraction. (2) Cases of no triple fusion, followed by endosperm formation, are humerous. In some instances, there is not even polar fusion, each polar nucleus initiating endosperm formation independently. In other cases, the male nucleus may fuse with either of the polar nuclei, the other nucleus remaining out of the combination, but the result is always the same. When the male nucleus pairs only With the micropylar polar nucleus, one might expect an embryo, if the latter nucleus is really an egg, but endosperm is the result. The increasing number of known angiosperms which are habitually parthenogenetic furnish cases of endosperm formation in the absence of the male nucleus. Of course in such cases the endo- Sperm may be claimed to be parthenogenetic also. The cases of so-called parthenogenesis among angiosperms illustrate a wider variation in the antecedents of endosperm forma- tion than the mere absence of the male nucleus would seem to indicate. STRASBURGER has called attention to the fact that in the cytologically investigated cases of parthenogenesis there has been no reduction division, and that therefore the parthenogenetic €gg is a 2x egg, just what it is after normal fertilization. If the failure of reduction results in a 2x egg, it must result also in 2x Synergids, antipodals, and polars; in other words, the gameto- phyte has throughout the sporophyte number of chromosomes. And still, endosperm formation proceeds as before, when one would be justified in expecting embryo formation by sporophytic budding, @ phenomenon very common in the tissues adjacent to the embryo Sac. No one questions that the embryo is a sporophyte, whether it is a result of the act of fertilization or not, for it is recognized by its organization. It is pertinent to ask, therefore, why there Should be any hesitation in recognizing the endosperm as gameto- Phytic from its lack of organization, no matter how it originates. It is obvious that the constancy of endosperm lies in its structure and not in its origin. 384 BOTANICAL GAZETTE [NOVEMBER From the facts in hand, the following statements seem to be justified: (1) Endosperm formation is not dependent upon the presence of a male nucleus. (2) Endosperm formation is not even dependent upon polar fusion. (3) Therefore, both of these fusions may be regarded as supple- mentary rather than determinative. (4) Endosperm formation does not even depend upon having been preceded by a reduction division. 5) The fusions associated with endosperm formation do not represent a definite process, but are miscellaneous in number and order. é (6) The product of such fusions as do occur is merely an undif- ferentiated tissue, which practically continues the tissue of the gametophyte; that is, it is simply growth and not organization. Conclusions It seems evident that the egg has an-organization peculiar to itself. A male cell may fuse with any other cell in the sac, and the result is only endosperm; but occasionally such a fusion (as with a synergid or a polar) results in an embryo. This implies that, for - some reason, these ordinarily sterile cells have achieved the organl- zation of eggs. It is this possibility that makes them potential eggs; but in the ordinary embryo sac of angiosperms there is only one actual egg, which means only one cell capable of being fertilized in any real sense, and therefore capable of producing an embryo. Conditions in the embryo sac favor fusions of any free nuclel, in any number and of any origin. A male nucleus, perhaps, 1S more apt to enter into fusions than any other kind. A male nucleus entering into a fusion may or may not express itself as a carrier of hereditary characters. If it does express itself in this way, it is like injecting certain gamete tendencies into 4 vegetative fusion; therefore, it is more probable that the male nucleus modifies somewhat the normal product than that the ant podal polar (a vegetative nucleus) modifies a normal product. In 1911] COULTER—EN DOSPERM OF ANGIOSPERMS 385 other words, the vegetative fusion is more apt to arcana the normal situation than a sexual fusion. There is no necessary phylogeny of such a performance. It is more a physiological problem to discover the conditions in the embryo sac of angiosperms that favor miscellaneous nuclear fusions. The final conclusion seems to eo that free nuclei within the embryo sac, containing a variable number of chromosomes and reacting to one another in various ways, are in a condition to con- tinue division, and this division is usually carried forward to tissue formation. The whole history of the megaspore and its products justifies us in regarding this tissue, however formed, as gameto- phytic. THE UNIVERSITY OF CHICAGO Note.—Since this paper was in type, there has appeared a paper by CAMPBELL on the embryo sac of Pandanus,' which supplies another illustration of the indefiniteness of the nuclear fusions Within the sac. In this case there is an extraordinary development of antipodal tissue before fertilization, and a varying number of free antipodal nuclei fuse with the micropylar polar to form the large primary endosperm nucleus. In some cases two primary endosperm nuclei may be formed by these multiple fusions, and it would seem to make no difference in the result whether the “ second male nucleus” fuses with one of them or with neither of them. In either event, it is obviously a vegetative fusion. Ann. Botany 25:773-789. pls. 59, 60. figs. 2. 191T. SOME PROBLEMS IN CECIDOLOGY Mei ¥, -Coox It is very doubtful if any phase of biology has been neglected more than that very conspicuous and extremely puzzling branch known as cecidology. This subject in its broadest sense includes all forms of abnormal plant growth regardless of cause. It must include, therefore, not only the hypertrophies, but also the witches brooms. It must include the abnormal growths caused by flower- ing plants, fungi, bacteria, insects, nematodes, and chemical and mechanical injuries. It must also include that great number of abnormal growths from unexplained causes which are included under the general term of teratology. Unfortunately, many of the botanists have interpreted the subject to include only those cecidia which are the result of insect injuries, and have attempted to relegate the entire subject to the entomologists, although they have not hesitated to study the cecidia caused by nematodes and bac- teria, which might just as reasonably be forced upon the zoologist and bacteriologist. The fact that the mycologists have usually been interested in the fungi and not in the host plant, explains why so much interest- ing material has been thrown aside with the single comment, “bugs.” But with the development of plant pathology, a branch of botany which is necessarily interested in the pathological con- dition of the host, there is no longer any excuse for not giving 4 reasonable consideration to all phases of cecidology. It is the purpose of this paper to call attention to some of the problems involved in cecidology, and to their bearing on other phases of biology, more especially botany. Cecidology is as old as the science of biology, and cecidia are referred to in some of the earliest biological literature. That cecidia were the subject of speculation, if not of study, is evidenced in the writings of REDI," who, like other vitalists of his period, believed plants were endowed with souls and that the soul of the plant controlled the formation * REDI was born in 1626. Botanical Gazette, vol. 52] [386 Igr1] COOK—PROBLEMS IN CECIDOLOGY 387 of both the egg (i.e., the gall) and the insect which emerged from it, and determined their specific characters. As in all other biological subjects, the first real scientific work was taxonomic in character, and in 1686 Ma.picut, who was a physician to Innocent XII and professor of medicine in Bologna and later in Messina, published his De Gallis, in which he gave quite accurate descriptions of the known galls of Italy and Sicily. Following this work, which may be looked upon as the starting point for cecidology, LINNAEUS and many other later writers gave more or less attention to this subject, which has attracted so much attention in Europe during recent years. _ In America, the pioneers in this subject were Baron C. R. OsTEN-SACKEN, BaAssETT, WALSH, Ritey, Fitcu, SHIMER, and Harris, all of whom were entomologists. Although the entomologists have done more work in cecidology in both Europe and America than the botanists, their work has been no broader. The entomologists have studied the insects and described the cecidia which were attributed to them, and in the case of the injurious species have devised means for their con- trol. The botanists have done the same work for fungi which cause cecidia, and have also invaded the fields of the bacteriologist and zoologist and studied not only the cecidia produced by bacteria and nematodes, but have even studied the organisms. Taxonomy seems to be the forerunner of all lines of biological work, and this has been true of cecidology, but we have now reached @ point from which we can extend our studies into other phases of the subject. We can now study the subject with reference to other phases of biology, in fact other phases of biology are encroach- ing upon the subject of cecidology. With this new development, the entomologist, the mycologist, and others will continue to find ample fields for the study of taxonomy. The entomologist will also have those almost untouched fields of life history and of alter- hation of generations which came so near to demonstration by our fellow-countrymen, H. F. Bassett, and which was afterward demon- Strated by HERMAN ADLER. The various groups of botanists will find especially. rich and almost untouched fields in many directions. The anatomical and histological characters and the development of cecidia have 388 BOTANICAL GAZETTE [NOVEMBER been the subject of extensive studies in Europe, but have received very little attention in America. These studies when properly carried out and correlated with the work of the taxonomists will in turn open broad and unexplained fields in evolution. The pathol- ogy of the plants which are suffering from the attacks of these many cecidia-producing organisms cannot be overlooked by the plant pathologists, who have no more right to refer insect cecidia to the entomologist than the surgeon has to send the patient suffer- ing from a gun-shot wound to the gunsmith. Both the economic entomologist and the plant pathologist will find enough problems to keep them busy for many years to come. It is doubtful. if the. entomologist has said the last word on the Phylloxera vastatrix, Schizoneura lanigera, Eriophyes pyri, and many other cecidia- producing insects which attack economic plants; and it is undoubt- edly true that the plant pathologist has scarcely touched many of the economic problems involving cecidia-producing fungi and bac- teria. The cytologist will also find a field for his labor. However, the most difficult and probably the most fruitful field is open to the plant physiologist; the character of the stimuli which excite malformation is a question well worth the attention of any group of scientists, and one which if answered may be very far reaching in its influence. The botanists have doped the plant with many chemicals, with some of which it may never come in contact in a state of nature; they have subjected it to the various kinds and degrees of gases, light, moisture, and temperature; treated it with electricity; prodded it with everything imaginable from a most delicate needle to a crowbar; and otherwise subjected it to various normal and abnormal conditions, but have made little or no effort to determine the character of the stimuli which cause the formation of cecidia. Darwin and all his predecessors believed that the cecidia are directly or indirectly the result of a chemical secreted by the mother insect at time of oviposition; MALpIiGHI believed that the chemical causes a fermentation of the juices; ReavumuR? held the same view, but also believed that the thermal effect of the egg and the character of the wound, which varies with the different species of the insect, are important factors. Sir 2 WMA. < eo a ' toire desinsectes. Mémoire XII. Vol. 111. 1733+ tort] ; COOK—PROBLEMS IN CECIDOLOGY 389 James Pacet, as late as 1880, said that “‘the most reasonable, if not the only reasonable theory, is that each insect infects or inoculates the leaf or other structure of the chosen plant with a poison peculiar to itself.” Unfortunately, this view is still held by most of our biologists, although the researches of the past thirty years have demonstrated that it is almost without foundation. In 1881 Dr. HERMAN ADLER? published the results of his long and careful studies, in which he gave the first real scientific evi- dence concerning the nature of the stimuli and character of gall formation. According to his results, the fluid secreted by the oak- gall fly is not irritating, and is not a factor in gall formation, but May serve as an antiseptic dressing for the wound in the plant. This view is strengthened by BEYERINCK,' who demonstrated that the fluid is without taste or smell and not irritating when injected under the skin. ApLER advanced the idea, which has been affirmed by other workers, that in the oak-gall flies, whatever irritating chemical exists comes from the larva and not from the parent insect. ADLER also reports his observation on Nematus Vallismierii, one of the saw flies, which attacks the Salix amygdalina. In this case the female pours out an abundant glandular secretion at time of oviposition, and the gall is well formed before the larva emerges from the egg. It is also well known that mechanical stimuli will frequently Cause abnormal growths. However, accurate data upon the results of various stimuli is not to be found in our literature. ADLER says that the cecidia always originate from the formative cells of the plant, and that if the stimulation is applied to any other than the formative cells, cecidia are not produced. This statement Opens up an enormous line of work. While some scale insects cause hypertrophies, others do not. Who has traced the ramifications of the mouth parts of these insects through the tissues of the host ? Why do some Uredineae cause cecidia while other closely related Species do not? Who has traced the mycelia of these related species ’ Ueber den Generationswechsel der Eichengallen. sais Wiss. Zool. 35: T5I-246. 1881. Translated in 1894 by CHARLES R. STRA ‘ Beobachtungen iiber die ersten seca cl chain einiger Cynipidengallen. Naturk. Verli. der Kon. Akad. Deel 22: 179. 1882. 39° BOTANICAL GAZETTE [NOVEMBER in their ramifications through the tissues of the host plants? Who has solved the chemical and enzyme relationships which may exist between these fungi and their hosts? If the insect cecidia are the result of chemical stimuli, how about the myco-cecidia? If the insect cecidia are due to mechanical irritation, how about the myco- cecidia? If the insect cecidia are the result of irritation applied to the formative cells, is the same thing true for the myco-cecidia ? By what school of biologists should these problems be worked ? Will not the solution of one set help in the solution of others? — The writer is not presenting these questions for the purpose of controversy, but merely to call attention of students to this enormous field of plant pathology and plant physiology. Give us more data concerning the relationship between parasite and host plant, regardless of the character of the parasitic organism. Let us tear away the artificial barriers and give the broadest study to these problems. DELAWARE AGRICULTURAL Hse STATION NEWARK, DELAWAR AN ELECTRICAL CONSTANT TEMPERATURE APPARATUS CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY I51I W. J. G. LAnp (WITH FOUR FIGURES) The temperature of incubators heated with gas taken directly from the mains is very irregular when an attempt is made to con- trol the flow with mercury-actuated thermostats commonly used. - Most mercurial thermostats will compensate for slight variations from the mean gas pressure, but not for large ones. The rise in temperature in the water-jacketed incubators used in the Hull Botanical Laboratory for paraffin infiltration was so sudden and so high that delicate plant tissues were often much distorted. Electrically controlled heaters have been placed on the market tecently by makers of repute, but the price of the apparatus ($50 and $100) is unreasonably out of proportion to the cost of material and labor. In order to test the effect of definite temperatures on plant tissues for a longer time than is usually employed in imbedding, and having a direct current of 110 volts constantly on in the laboratory, the problem of devising a simple and efficient electrically controlled heater was first attacked about four years ago. The conditions of the problem were that the apparatus must maintain a definite temperature constant within very narrow limits for weeks at a time, must be easily adjustable to temperatures ranging from 40° C. to 80° C. with certainty, must be absolutely automatic in action, must be readily attachable to the usual type of ovens, must require practically no attention to keep in order, must be simple and inexpensive to construct, must use a minimum quantity of electricity, and must not be easily put out of adjustment by inexperienced or meddlesome persons. For over two years the apparatus here described has replaced the gas heaters in this laboratory, with satisfactory results. The tisk of fire, always great when gas is used, has been eliminated. 391] [Botanical Gazette, vol. 52 392 BOTANICAL GAZETTE [NOVEMBER So many requests for information concerning the apparatus have - been received that it has become impossible to give individual replies. The apparatus consists of a metallic thermostat (fig. 1) placed on a shelf in the oven, a water-jacketed heating coil (fig. 2) fastened to the bottom of the oven in such a way that the water jacket of the coil forms a continuous system with that of the oven, and an auto- matic switch (fig. 3) placed wherever convenient. The thermostat (fig. 1, 2) is a thin strip of iron about 1 mm. thick and 2 cm. wide, firmly riveted to a strip of zinc the same width and nln Fic. 1.—Diagram of thermostat and connections; , thermostat of zinc and iron; d, screw for adjusting temperature; 5, b’, binding posts to connect with #, ¢’ of the switchboard. from 1.5mm. to 3mm. thick. One end is fastened to a brass post set rigidly on the slate base, and the other end swings free. The free end of the metal tongue has a contact point of platinum fastened to the zinc side near the end. The adjustment for temperature is made with a platinum-tipped screw (d) set so that its point can always be brought in contact with the platinum disk on the metal tongue. The metal tongue and the adjusting screw are connected respectively with the binding posts (8, b’), as shown in the diagram. The base of the thermostat should be made long enough to fit easily in the oven, the ends resting on ledges provided for the upper shelf. The sensitiveness of the thermostat depends, of course, on the length of the metal tongue. If extreme sensitiveness is requir ed, it may be made nearly twice the length of the base and bent toa U, or it may be much longer and coiled. In practice 20 cm. has been found satisfactory. The zinc strip should not be thinner than 1911] LAND—CONSTANT TEMPERATURE APPARATUS 393 1.5 mm., or the thermostat will respond unpleasantly to any tremor of the bath or even in the laboratory building. If desired, brass or aluminium may be substituted for the zinc. The regulating screw should be made long enough to provide for quite a range of tempera- ture. When the thermostat has been adjusted to the required temperature, it will need no further attention, except perhaps to brush the dust from the contact points at very long intervals. To raise the temperature turn the screw to the right, to lower it turn it to the left. The heater (fig. 2) is a water-jacketed resistance coil of brass tubing and German-silver resistance wire. The tubing need not be thicker than 1 mm. The coil should be proportioned to the size of the oven it is intended to heat. .For ovens having internal dimensions of 20X 2526.25 cm., and for temperatures of 30°- PC., the size given here has been found suitable. Such a coil, however, will heat much larger ovens satisfactorily. The brass tubes should be about 15 cm. long. The resistance coil is four layers of no. 21 German-silver wire, wound on a tube 3 cm. inside diameter. The layers of wire are carefully insulated from the tube and from each other with asbestos paper about 0.6 mm. thick. The wire is wound with an engine lathe 24 turns to the inch under considerable tension, and the ends are brought out to binding posts (s, s’) in the slate head of the coil. Wound as described, the current at r10 volts measures about 2.2 amperes. The water jacket is made of 3 concentric brass tubes, the outer one being 6.25 cm. in diameter, the middle one 4.5 cm., and the inner one 3 cm. outside diameter, so that the tube of the heating coil will slip over it in close contact. The inner tube is closed at the lower end with a brass disk soldered tightly in place. The upper end remains open, and is fastened to the middle tube by a brass ring. The lower end of the middle tube is in turn fastened in'a similar manner to the bottom of the outer tube. A hole is cut in the outer wall of the bottom of the oven, and the outer tube soldered directly to the bottom. If preferred, the outside tube may be threaded and screwed into a flange soldered to the bottom of the oven. If this method is used, a rubber gasket should be Placed between the flanges, as shown in fig. 2. This arrangement 394 BOTANICAL GAZETTE [NOVEMBER o 00 () ° 90000 0.00000 000 oo 00 oo 00 ROWIMAHHLTH ooo oo 000 ' ° $0 20°00 20°0% 0°00 %% 990000 COOG 9 3"0°n "0 "5°00 0 0°00 00 OOOO a 0 Oo NOOO”, ° ) 9 ° ° ° ° ° ° ° ° ° ° ° ° ° ° ° 9. ° —— go emaigyperis 1] —Fo —— 2°, —— 9°, ° 3 °. ° ° ° ° ° ° c) ° ° ° ° ° ° ° ° ° ° 9 9° 9960.00 000000000000 000 000000 °. orororeronn, oo ° 0°00 7090 "0 90070070 0°00 900 20.20 90. 89 96 20.200 90°02 070% 0000 ©°0 0 5% Pe a Ul Y Hl 6 PSD aE \ g iz ereeaneeaS s Ss s* Fic. 2.—Median longitudinal section of heater, showing method of construction of water jacket and resistance coil, and how it is attached to the oven; s, s’, binding posts to be connected with h, h’ of the switchboard. 1913| LAND—CONSTANT TEMPERATURE APPARATUS 305 adds slightly to the cost, but will permit the sediment which appears in water-jacketed baths to be removed easily. Great care must be taken to have all joints absolutely water tight, since a leak will cause the destruction of the resistance wire in a few hours. An inspection of the diagram (fig. 2) shows the arrangement is such that the resistance coil is completely surrounded by water except at the.lower end, thus insuring rapid conduction of heat. Also the coil can be removed easily if repairs are ever necessary. - 3.—Diagram of automatic switch; p, p’, binding posts to connect with Source a electrical supply; e, op ta a, armature and switch; r, gasket for lamp rheostat; #, ¢’, binding to be connected with thermostat; ¢c, container for mercury (m, m); ki; Se binding et to be connected with heating coil. In two years’ use, only one has needed repairs, made necessary by spilling water on the head of the coil when the water jacket was being refilled, The automatic switch (fig. 3) is a slate base having an electro- magnet (e), armature (a) with switch, and a lamp rheostat (7) at one end, and the slate cups (c) filled with mercury at the other. A convenient size for the slate base is 20X11.25 cm. The magnets, which can be had very cheaply from electrical supply houses, should have a resistance of about 20 ohms. The armature (a) should be fastened by a spring to a pillar rigidly attached to the baseboard, 396 BOTANICAL GAZETTE [NOVEMBER and should extend about 15 cm. to form the arm of the switch. Care must be taken not to have the spring too strong, or the arma- ture will not be pulled down when the current flows through the coils of the magnet. The spring may be much weaker if an 8 or 4 candle power lamp is used instead of a 16 candle power lamp theostat. One wire connects the post p directly to ¢; the other post p’ is connected through the electromagnet ¢ and the lamp rheostat socket r with ?’. _ The switch end of the armature should have two iron pins extending downward at a right angle, sharpened, and tinned to insure good contact with the mercury in the cups c. In practice it is advisable to drill two holes in the switch arm, tap them, and use iron machine screws for contact points. The screws should be provided with lock-nuts to hold them at the proper length. Switch points gradually wear away, due to the small arc which always occurs when contact with the mercury is broken. The machine screw device permits compensation for this wear. The screws should be sharpened of course, to minimize splashing, and tinned. The double cup (c) for holding the mercury (m, m) should be made of slate. A convenient sized block is 5X3.75X2-5 cm. The holes for mercury should have a diameter not less than 1.25 CM™., preferably 2 cm., and the edges should be chamfered. The mercury oxidizes somewhat rapidly, and in consequence the volume should be rather large. Oxidation of the mercury is the chief defect of the apparatus, but no way has yet been found to prevent it. To compensate for oxidation, a small quantity of mercury must be added occasionally. One wire conriects the post p with one of the mercury cups, the other cup is connected with #. The post p’ is connected directly to h’. The switch (fig. 3) may be put in any convenient place, prefer- ably out of reach of inquisitive persons. Attach the heating coil (fig. 2) to the oven and place the thermostat (fig. 1) inside the ores on the upper ledges and connect the posts p, p’ of the switch with any convenient lamp socket, fill the cups c with mercury, screw a lamp in the socket 7, connect the posts ¢, ¢’ with 6, b’ of the thermo- stat. Connect h, h’ (fig. 3) with s, s’ (fig. 2) of the heating coil. These connections are shown in fig. 4,a photograph of the apparatus. rort] LAND—CONSTANT TEMPERATURE APPARATUS 307 It is realized that most botanists are not electricians, and therefore the description of the construction and wiring of the instrument is not written for experts. The action of the apparatus is as follows: When the platinum points of the thermostat are in contact, the current flows through Fic. 4.—Photograph of thermostat, heater, ana switch, with connections. the electromagnet, the armature is drawn down, closing the switch and making a circuit through the heating coil. The circuit will remain closed only so long as the platinum points of the thermostat are in contact. As the temperature of the oven rises, the platinum points are separated, the circuit through the electromagnet is broken, and the switch is opened by the release of the armature. 398 BOTANICAL GAZETTE [NOVEMBER When the temperature of the oven falls below the required point, the thermostat again functions and the switch is instantly closed. This action continues automatically as long as the current is supplied, or until the mercury in the cups is all oxidized. In one instrument it was found that a difference of o.01° was sufficient to actuate the mechanism. As has been said before, turning the adjusting screw to the right adjusts for higher temperatures, and vice versa. It will be seen that the two circuits are absolutely independent of each other, and that when the oven is at the required temperature both circuits are broken; that the electricity is only on when the temperature is below the required point. Because the switch closes so sharply when the thermostat functions, it is advisable to drill a small hole in the core of the mag- net nearest the switch and insert a rubber plug for a buffer. If the mercury splashes too much, rubber corks, with a hole in the center, may be put in the tops of the cups. The flash which occurs when the switch points leave the mercury is bright, but it does no harm. It is possible to use an alternating current, but it is very difficult to adjust the armature spring so as to avoid the unpleasant hum- ming. It is planned to try a weighted or balanced armature with alternating currents. A battery may be used to actuate the switch if magnets of lower resistance are used, and the lamp rheostat replaced with a plug; then the alternating current may be used to heat the coil in the oven. If preferred, the lamp used for a rheostat may be placed in the oven and connected to the socket on the switchboard with a cord and plug. This arrangement is very convenient, for the instant the door of the oven is opened the lamp is lighted. Also the heat of the lamp increases the efficiency of the apparatus. Anyone at all familiar with tools can construct the apparatus at a cost of about $3.75 for material. Of course he must have access to an engine lathe to wind the coil so that the wires will not touch each other. After the first experimental instrument was found to work satisfactorily, the interest of a very expert mechani- cian, Mr. A. W. Srrickrer, 1311 E. 57th St., Chicago, Ill., was enlisted. He suggested many improvements, always having in mind increase of efficiency and lowering of cost. It is largely due 1911] LAND—CONSTANT TEMPERATURE APPARATUS 399 to his interest in the problem and his skill in construction that the apparatus has proved so efficient in this laboratory. He has recently devised a form of this thermostat which can be used with safety where explosive gases are present. He finds that when made as described here the cost should not exceed $15.00 for the apparatus complete and ready to attach to the incubator. THE UNIVERSITY oF CHICAGO BRIEFER ARTICLES APOGAMY IN PELLAEA ATROPURPUREA In the course of a study of fertilization and related phenomena in several ferns, a culture of Pellaea atropurpurea (L.) Link was found to have developed embryo sporophytes apogamously. The spores of this species were collected in October and sown on clay soil December 13, 1910. The soil was sifted into a small pot, moistened with water, and sterilized in an oven. The culture was kept under a bell jar in a Wardian case in the university greenhouse. Watering was found necessary but once, and was accomplished from below with — water. t The prothallia grew rather rapidly, and hundreds carefully exam- ined at various times showed no indications of antheridia or arche- gonia. Two and one-half months after the spores were sown, the first indications were noticed of the development of apogamous embryos. Many prothallia were again examined on both surfaces for the appear- ance of sex organs, with negative results. On March 13, 1911, 110 prothallia were examined with special care; 47 bore sporophytes in various stages of development, but no sex organs were found in any case. At an early stage in development it is difficult to distinguish between young antheridia and rhizoids. Young antheridia may be hidden among the rhizoids and escape attention; rhizoids, however, were in no case produced in great abundance in the culture in question. Thus the possibility is not excluded that rudimentary antheridia may have been formed; but my observations make it certain that none developed beyond the earliest stages, and that no archegonia were produced on these prothallia at any time. The prothallia of this fern are of a darker green color than the pro- thallia of several other species in my cultures. They are generally heartshaped with a deeply cut notch, but many irregularly shaped pro- thallia occur. The first appearance of the apogamous embryo is indi- cated by a small darkened area usually a short distance back of the growing point. This, as sections made at this time show, represents 4 region of active division, the prothallial cells concerned being much Botanical Gazette, vol. 52} -— Igrt] BRIEFER ARTICLES 401 smaller than the neighboring ones which are not concerned in embryo formation. Embryos are formed on the inner sides of the lobes, as well as a-short distance back of the apical notch. Long ribbon-shaped prothallia without apical notches also develop sporophytes at their distal ends. Sporophytes are often formed, therefore, in regions quite distinct from the meristematic area in which archegonia are ordinarily developed. Soon after the beginning of embryo development, hairs appear surrounding the region of active growth. These originate from the area of the prothallium which is involved in the development of the embryo. Still later, the embryo projects from the prothallium, some- what inclosed by the hairs, each of which is composed of several cells with large nuclei. As the embryo continues to grow, the primary leaf, from the petiole of which numerous hairs develop, makes its appear- ance. Later the primary root and stem are formed. At no time was there any evidence of the development of a structure which could be thought to correspond to a foot. In several cases two sporophytes began their development on the same prothallium. From studies so far made, it appears that both interior and surface cells of the pro- thallium are involved in the formation of the sporophyte. During the present season, apogamous embryos have begun their development upon a large number of prothallia of this species in four cultures growing upon peaty soil. The first embryos were observed about one month after the sowing of the spores. : So far as I know, apogamy has not been previously reported in Pellaea atropurpurea, although Worontn (1907) reported its tnaest tence in P. flavens, P. nivens, and P. tenera.—W. N. Stet, University of Wisconsin, Madison. CURRENT LITERATURE BOOK REVIEWS Vegetation der Erde TX. AFRICA As previously noted in these pages,t ENGLER has in contemplation an elaborate phytogeographic treatment of tropical Africa. The second volume of this series was the first to appear, and it is now followed by the first volume, which is issued in two parts.? The first volume is devoted to as much detail as is now possible to a consideration of the vegetational conditions of Africa. This volume makes it particularly clear that Africa is no longer the “unknown continent”; particularly is this true, so far as tropical Africa is concerned, of the German possessions, each of these being well delineated phytogeograph- ically by maps in colors. Most of the volume is taken up bya presentation of the chief phytogeographical subdivisions of Africa, which, as here treated, are (r) Mediterranean Africa with the bordering parts of the Sahara, (2) trop- ical East Africa, (3) the southwestern region of winter rain, (4) the summer rain region of West Africa, (5) Macronesia. This portion of the work is richly and beautifully illustrated by photographs of desert landscapes in North Africa, cuts of representative Saharan plants, and by similar photographs and cuts in much greater number from tropical East Africa, including especially Abyssinia, the Somali Peninsula, and German East Africa. The account of the summer rain region of West Africa also is very full and is finely illus- trated, especially in the portions dealing with the German territory. The work closes with a treatment of the general geographic conditions (including temperature and precipitation data, and an account of the various types of soils), a short description of the regions at different altitudes, a brief survey of the plant formations, and an account of the floral constituents and the general floristic relationships of Africa. Under the last head many genera are tabu- lated as to their affinities, whether pantropic, paleotropic, endemic, ¢tc. Also there is a short account of the geological development of the present vegetation. XI. THe BALKAN COUNTRIES Apamovié, who for many years has published important papers dealing with the vegetation of Servia and neighboring lands, has now issued a mono- * Bot. Gaz. 50:468. 1910. * Encter, A., und Drupe, O., Die Vegetation der Erde. IX. ENGLER, A., Die Pflanzenwelt Afrikas insbesondere seiner tropischen Gebiete. Bd. I. pp. xxviii 1029. _maps 5. pls. 47. figs. 708. Leipzig: Wilhelm Engelmann. 1910. (subscription M 45). 402 td] git} CURRENT LITERATURE 493 XII. THe PERUVIAN ANDES : This volume is the second one of the series to treat of American vegeta- ag The general plan of the other volumes is followed, though the con- sideration is mainly floristic, very little being said regarding the formations.‘ EBERBAUER, the author of the treatise, has spent several years of study in Peru, and is known to plant geographers by various papers dealing with Peru- vian vegetation. Following the usual bibliography of literature and an account of the topography and climate, there is a survey of the plant families represented. Most of the volume is devoted to a detailed account of the vegetation by “zones,” that is, by altitudinal subdivisions. These subdi- visions are the Misti zone (2200-3400 m.) and the Tola zone (3400-4300 m.) on the western slope in southern Peru, the Loma zone of the coast, the north- €rn desert zone, the central Sierra zone, the northern Sierra zone, the high a atin > ENGLER, A., und Drunk, O., Die Vegetation der Erde. XI. Apamovié, L., Die Vegetationsverhiiltnisse der Balkanlinder (Méische Linder) unfassend Serbien, Altser- len, Bulgarian, Ostrumelien, Nordthrakien, und Nordmazedonien. pp. xvit-567. maps 6. pls. 41. figs. 11. Leipzig: Wilhelm Engelmann. 1909. M 40 (subscrip- tion Mf 30). 4, Die Vegetation der Erde. XII. WeEBERBAUER, A., Die Pflanzenwelt der Peruanischen Anden. pp. xii+355. maps 2. pls. go. figs. 63. Leipzig: Wilhe' Engelmann. tgt1. M 28 (subscription M 20). _ 404 BOTANICAL GAZETTE [NOVEMBER Andes or Puna with its wonderful xerophytic forms, the eastern sclerophyll forests, the northern Paramo, and the luxuriant eastern tropical forests. This part of the work is rather fully illustrated by excellent cuts and photographic reproductions. A short section follows on the culture plants, the volume concluding with an account of the geological development of the Peruvian flora, mostly in the form of tabulations.—H. C. CowLes. Plant life of Maryland “The plant life of Maryland”’s is the title of a volume issued as a Special Publication of the Maryland Weather Service, and is one of a series of reports of unusual completeness and excellence. The first of these reports dealt with the physiography and meteorology of the state; the second with the climate and weather of Baltimore and vicinity; and this, the third volume, presents the plant life in its relations to the physiography and climate, also inquires into the correlations between natural vegetation and crop possibilities, and: includes the agricultural features and forest resources of the state. The main part of the volume is by SHREVE, who directed the botanical survey. His introduction summarizes the geography, climatology, topog- raphy, mineralogy, and soils of Maryland. In Part II, after a brief history of field botany in the state, he discusses the floristics according to the present knowledge of the flora, comparing the three zones (coastal, midland, and mountain) with respect to the number and species of plants, and the floristic relations of the zones to each other and to other regions. Part III occupies the body of the book and presents the ecological plant geography. SHREVE considers first the eastern shore district of the coastal zone under the several divisions: upland, swamp, marsh, aquatic, dune, and strand vegetation. Comparison of this district with the coastal plain of New Jersey and of the southern states brings out striking variations. CHRYSLER treats the western shore district of the coastal zone under the following topics: forests (upland, lowland, and cypress swamps), marshes (fresh and salt), peat bogs, strand, and cultivated plants, the chief interest being in his discussion of the succession of the forest types and in the transition of salt to fresh water marshes, this region affording unusual opportunities for such studies. In the lower district of the middle zone, the vegetation is classified by SHREVE according to the soil types, the topographical and general physical conditions being here uniform, and the vegetation less diversified than elsewhere. The upper district of the midland is divided into four natural belts of ridges and valleys, and the characteristic plant life of these divisions is discussed by BLopcetr. SuReEve describes the mountain zone under seven headings: slopes, LEY oe W.1 orResT, Curyster, M. A., Biopcetr, Freperick H., and Brs- , F. W., The plant life of Maryland. 4to Baltimore: hns Hopkins ryland. 4to. pp. 533. pls. 39. figs. 15- Jo Press. rort. : Igrt] CURRENT LITERATURE 405 ridges, valleys, rocky slopes, glades, swamps, bogs, the topography determining in each case the character of the vegetation. In Part IV, on the “Relation of natural vegetation to crop possibilities,” SHREVE concludes that only in a general way may the native or introduced plant cover, as seen today, be significant of agricultural capabilities, although there is evidence that the virgin forest did give indication of the char- acter of the underlying soil which was observed to advantage by the early settlers. Part V, on the “Agricultural features” by BLopGett, Part VI on the “Forests and their products” by F. W. BEstey, and Part VII, a “List. of plants collected or observed” by SHREVE, complete the book. € careful work of the authors and the collection of the floristic and ecological data make this a valuable treatise of its kind. It is handsomely Printed and abundantly illustrated. For regions presented in such detail and with many local references, the lack of adequate maps is often noticed.— Lavra Gano. MINOR NOTICES Wettstein’s Handbuch.—The mere fact that a second edition of a book has become necessary indicates that it has met someneed. The second edition of WetrstEIn’s Handbuch® does not differ essentially from the first edition. Minor inaccuracies have been corrected, additions have been made both from the rapidly increasing literature and from the author’s own investigations, and a large number of illustrations, of the same high grade which made the first volume useful, have been added. As in the first edition, the work on angiosperms is particularly extensive, occupying about one-half of the entire book. This part of the work presents a compact, profusely illustrated account of all the more important families, which should give the beginner a sound foundation for advanced work, and which cannot fail to be helpful even to the Professional taxonomist. « It is encouraging to note that in discussing the phy- logeny of angiosperms, the monocotyls are derived from the lower dicotyls.— HARLES J. CHAMBERLAIN. Ornamental shrubs.—It is safe to predict that the latest handbook by APGaR,? while intended for the general public, will prove most useful to the teaching botanist who has occasion to draw much of his material from parks and greenhouses. In its scope the volume includes not only native and hardy shrubs, but also introduced forms, many of which are conservatory plants in the northern United States. Numerous keys, based mostly upon leaf characters, appear to be most efficient in aiding the student to identify ee area nt 6 Wetrstemn, R: V., Handbuch der systematischen Botanik. 2d edition. 8vo. PP. viiit-or4. figs. 600. Leipzig: Franz Deuticke. 1910. M 24. 7 ApGar, Austin C., Ornamental shrubs of the United States. 12mo. pp. 352. Jigs. 621. New York: American Book Company. 1910. $1.50. 406 BOTANICAL GAZETTE [NOVEMBER species even when they are not in flower. The keys are supplemented by simple descriptions and by more than 600 illustrative drawings, while a glossary of botanical terms will prove useful to the beginner, and the size of the book will recommend it to all as a most useful pocket aid to the study of a com- paratively unknown portion of our flora—Gro. D. FULLER. Dictionary of plant names.—GERTH VAN WIjK;,' a teacher in the schools of Holland, has published the result of a most laborious compilation of data, extending through twenty-five years. The dictionary is intended to enable one to find the vernacular name of a plant in four languages, provided he knows its scientific name; the four languages chosen being English, French, German, and Dutch. Two other parts are promised, which will really form an index to the first parts, and will enable one to find the scientific name of a plant if he knows the vernacular name in any one of the four languages. questions as to the usefulness of such a work are submerged by amazement at this exhibition of enjoyment in endless drudgery.—J. C Album of thallophytes.—The first fascicle of an album of the algae, fungi, and lichens, by Couptn,? indicates that the complete work will be useful to all who are interested in the lower plants. All the genera and many of the more important species are illustrated by drawings emphasizing the features which are of importance in classification. The figures are in plates opposite the descriptions, and with the description of each species is a bibliography of the principal contributions, so that more extended information may be easily obtained.—Cuar es J. CHAMBERLAIN. Natiirlichen Pflanzenfamilien.—Parts 241 and 242 conclude the supple- ment to the Chlorophyceae by N. WILLE; include that to the Phaeophyceae and Dictyotales by the late F. R. Kyeriaan and N. SvEpELIus; and begin the supplement to the Rhodophyceae by N. SvEDELIUS, who continues it in parts 243 and 244. A new our eee of Lithodermataceae is described by SvEDELIUs.—J. M NOTES FOR STUDENTS. Current taxonomic literature.—O. Ames (Phil. Journ. Sci. Botany 6: 35- 56. 1911) under “Notes on Philippine orchids with descriptions of new species III” places on record additional data concerning this group of plants in the Philippines and describes 22 species new to science.—R. C. BENEDICT (Am. Fern Journ. 1:40-42. pl. 2. 1911) describes and illustrates a new species of *GerTH VAN Wyk, H. L., A dictionary of plant names. 2 parts. 4to. PP- xxiv+1444. Haarlem: Published by the Dutch Society of Sciences. 1909, 1910. * Coupin, Henrt, and Coupry, Mii. FERNANDE, Album générale des pate (algues, champignons, lichens). Fasc. x. pls. 1-15. Paris: E. Orlhac, Editor. a 1911] CURRENT LITERATURE 407 Anemia (A. nipeénsis) from Cuba. The same author (Bull. Torr. Bot. Club 38:153-190. pls. 2-8. 191 1) presents the results of studies in the fern tribe Vittarieae, recognizing 7 genera. Several new combinations are made and one new species of Polytaenium (P. quadriseriatum) is described from Hayti.— E. BETHEL (Mycologia 3:156~-160. pl. 48. 1911) describes and illustrates studies on “The ferns and flowering plants of Nantucket” recognizes 12 species of Rubus and characterizes 24 hybrids in this genus.—F. BorGESEN (Bot. Tidsskir, 30:177-207. 1910) under the title “‘Some new or little known West Indian Florideae II” has published critical notes on several species of the tisiphon) of the Siphoneae is proposed.—A. Brresapota (Med. Rijks. Herb. PP. 75, 76. 1911) has published 4 new species of Polyporaceae, two of which (Fomes subendothejus and F. surinamensis) are from South America.—F. uBAK (Ber. Deutsch. Bot. Gesells. 29:70-74. 1911) in an article entitled “Eine neue Krankheit der Maulbeerbiume” describes a new genus (Dothiorel- lina) from Bulgaria. The fungus is parasitic in the branches of Morus alba.— L. Buscattont (Ann. Botany 9:87-122. pls. 1-4. 1911) records several species of the Sympetalae from the region of the Amazon in Brazil and describes and illustrates new species in the following genera: Torenia, Drymonia, and Memora. —C. Dr Canpoite (Rep. Nov. Sp. 9:229-235. 1911) has published rr new species of Piper from Bolivia-—A. CHase (Proc. Biol. Soc. Wash. 24:103- 160. 1911) presents the results of further studies on the Paniceae, and includes a new species in the genus Valota and two in Axonopus. Two new genera are proposed, namely, Homolepis, based on Panicum aturense HBK., and Scutachne, based on Panicum durum Griseb.—T. F. CHEESEMAN and H. B. Hemstey (Kew Bull. 188, 189. 1911) have published a new genus (Coxella) of the Umbelliferae; the genus is founded on Ligusticum Dieffenbachii Hook. f.—E. Cutovenpa (Ann. Botany 9: 51-85, 125-152. 1911) under the title “ Plan- tae novae vel minus notae e regione aethiopica”’ has published several species of flowering plants and proposes the following new genera: Tzellemtinia of the Rhamnaceae, Hymenosicyos of the Cucurbitaceae, Erythroselinum and Ste- bhanarossia of the Umbelliferae, and Pefrollinia of the Compositae.—R. Cxo- DAT (Bull. Soc. Bot. Genéve II, 3:125, 126. 1911) has described a new genus (Ernstiella) of the Myxophyceae. The alga was found in one of the parks of Geneva.—H. N. Drxon (Journ. Bot. 49:137-150. pl. 513. 1911) has published several new species of Indian mosses and includes a new genus (Hyophilopsis Card. and Dixon) of the Pottiaceae.—S. T. Dunn (Kew Bull. 193-198. 1911) has published a new genus (Adinobotrys) of the Legu- minosae and refers thereto four species from the Indo-Malayan region and 408 BOTANICAL GAZETTE [NOVEMBER China. The same author in cooperation with Dr. Harms (Journ. Bot. 49: 106-109. 1911) has proposed a new genus (Craibia) of the Leguminosae. The genus, as here treated, embraces nine species of trees, all of African distribu- tion.—C. W. EpcGerton (Phytopathology 1:12-17. pl. 4. 1911) under the aa “Two new fig diseases” records two fungi found on the fig tree at Baton ouge, Louisiana, one (Tubercularia Fici) being new to science.—A. ENGLER on Jahrb. 46:1-288. pls. r-4. 1911) under the general title of “Beitrage zur Flora von Afrika XXXVIII,” in cooperation with several noted special- ists, publishes an important contribution to our knowledge of the flora of Africa. About 160 species are here published for the first time, and one new genus (Simarubopsis) of the Simarubaceae from central Togo is described and illustrated. The paper includes a synoptical revision of the African species of Ficus by J. MirpraEp and M. Burret. These authors recognize 95 species of this genus from Africa, and a key precedes their enumeration.—A. J. EWART, J. Wutre, and B. Woop (Proc. Roy. Soc. Victoria, N.S. 237: :485~304. pls. 49-57. 1911) under “Contributions to the flora of Australia, No. 16” have described several species new to science and propose a new genus (Sarga Ewart) of the Gramineae.—C. E. Farrman (Ann. Mycol. 9:147-152- 1911) under the heading “Fungi Lyndonvillenses novi vel minus cogniti” has pub- lished 8 new species of fungi from the vicinity of Lyndonville, New York.— —C, FERDINANDSEN amd O. WrncE (Bot. Tidsskr. 30:208-222. 1910) record several species of fungi obtained on the WARMING expedition to Venezuela and the West Indies in 1891-92. A new species is added to Helotium and one to Sterigmatocystis. Two new monotypic genera are characterized, namely, Myxotheca, found on the pinnae of Trichomanes pinnatum from the island of Trinidad, and Sp eo found on decaying fruits of cacao from Venezuela. —W. O. Focxe (Rep. Nov. Sp. 9:235-237. 1911) records 5 new species of Rubus from Central and South America.—R. E. Frres (ibid. 211) has published a new species of Wissadula (W. indivisa) from Paraguay.—E. L. (Leafl. Bot. Obs. and Crit. 2:121-152. 1911) has described upwards of 5° new species of flowering plants chiefly from western United States. One new genus (Sandbergia) of the Cruciferae is proposed. The same author (Am. Mid. Nat. 2:73-90. 1911) under the heading “ Antennaria in the Middle West” recognizes 13 species of this genus from the central part of the United States; of this number 7 are said to be new. A key to the species precedes their description —R. M. Harper (Torreya 11:64-67. 1911) records a new Prunus (P. geniculata) from Florida.—L. L. Harter (Mycologia 3:154, 155- t91t) has published a new species of Alternaria (A. Forsythiae) found at Washington on living leaves of Forsythia suspensa Thunb.—E. HASSLER (Rep. Nov. Sp. 9:145-160, 193-197. 1911) has published several new species and varieties of Leguminosae and Convolvulaceae from Paraguay.—F. HEDGES (Phytopathology 1:63~-65. pl. 15. 1911) describes and illustrates a new fungus (Sphaeropsis tumefaciens) from Jamaica; this fungus is said to be “the cause of the hoe and orange knot.”—F. Hrypricu (Ber. Deutsch. Bot. Gesells. Torr] CURRENT LITERATURE 409 2926-33. pl. 2. 1911) in an article entitled “Die Lithothamnien vor Roscoff” describes and illustrates a new genus (Sguamolithon).—R. H. Howe, Jr. (Mycologia 3:106-150. pls. 41-47. 1911) under the title ‘American species of Alectoria occurring north of the fifteenth parallel” recognizes about a dozen Species and records a new one (Alectoria pacifica Stzb.) from the Island of Guad- alupe off the California coast —G. KUKENTHAL (Philip. Journ. Sci. Bot. 6: 57-64. I9II) gives a synopsis of the Philippine Caricoideae, with a key to the species of Carex, 24 being listed for the Philippines, one (C. pycnothyrsos) hitherto unknown to science.—J. Lunett (Am. Mid. Nat. 2:57-60. 1911) records 4 hew species of Compositae from North Dakota, and (ibid. 90-94) under the title “New plants from North Dakota” characterizes 8 varieties of “Laci- maria scariosa.”—B. MACKENSEN (Bull. Torr. Bot. Club 38:141-143. 1911) Tecords 2 new species of Opuntia from Texas—W. A. MURRILL ‘(Mycologia 3*97-105. pl. 4o. 1911) in the eighth article on “Illustrations of fungi” describes and illustrates several plants and records new species in Omphalia, Inocybe, and Campanularius.—J. A. NrEUwLAND (Am. Mid. Nat. 2:60-6s. Torr) in an article entitled “The type of the genus Panicum” proposes a new generic name Chasea, and transfers thereto several species of Panicum. Pani- cum clandestinum L. is taken as the type of the newly constituted genus.— L. O. Overnorts (Ohio Nat. 11:353-373. to1r) under the heading “The known Polyporaceae of Ohio” records 118 species from that state-—A. Pa- SCHER (Ber. Deutsch. Bot. Gesells. 29:112-125. pl. 6. 1911) gives an account of a new tentacle-bearing chrysomonad, found growing in ditches on Mikro- Spora and Oedogonium at Franzensbad, Germany. ‘The plant has been desig- hated by the generic name Cyrtophora and together with Pedinella Wyssotzki and Palatinella Laut. are referred to a distinct family Cyrtophoraceae.— F. Perak (Rep. Nov. Sp. 9:177, 178. 1911) has published a new species of Cirsium (C. Greenei) from northern Mexico.—J. A. Purpus (Monats. fiir Kakteenk. 2r: 50-53. r911) describes and illustrates a new species of Mamil- laria (M. Sartorii) from Mexico.—C. B. Rosrnson (Philip. Journ. Sci. Bot. 6:1~33. pis. Z-3. tgtt) presents the concluding article in his consideration of the “Philippine Urticaceae.”’ In this paper 11 genera are recognized and to them are referred 43 species of which 13 are new. A new genus (Astrothal- mus) is proposed, which is based on Maoutia reticulata Wedd.—H. H. Ruspy (Bull. Torr. Bot. Club 38:145, 146. 1911) describes a new species of Mayepea and one of Morus from Mexico.—R. SCHLECHTER (Rep. Nov. Sp. 9:161-166, 212-218, 281-287, 289-294. 1911) under the title “Orchidaceae novae et Criticae”’ has published new species of orchids from different parts of the world, including several from Mexico and Central America. One new genus (Solenocentrum) is proposed from Costa Rica.—P. C. Sranpiey and J. C. BLUMER (Muhlenbergia 7:44-47. pl. 5. 1911) have described and illustrated @ new species of Castilleja (C. austromontana) from the southern Rocky Moun- tains—J. Sremer (Oesterr. Bot. Zeits. 61:177-183. 1911) had published several new species of lichens, including one (Buellia mexicana) from Mt. 410 BOTANICAL GAZETTE [NOVEMBER Hinatikatl, Central America.—G. S. West (Journ. Bot. 49:82—89. 1911) under the heading “ Algological notes’’ characterizes a new genus (Oligochaetophora) ; the genus is based on Polychaetophora simplex.West, which was found orig- inally growing on submerged portions of various aquatic flowering plants at Donegal, England.—J. M. GREENMAN. Cecidology.—Among the most important of the recent papers on galls is that by Denizor™ on the gall of Andricus radicis. This gall occurs on the roots of at least three species of oaks, and appears to resemble somewhat the American twig gall caused by A. punctatus Bassett. The gall is plurilocular, but its histological structure is very similar to the unilocular gall caused by A. sieboldi. e gall is made up primarily of parenchyma tissue, and each larva is surrounded by a definite structure as follows: (1) a zone of parenchyma tissue well filled with starch and known as the nutritive zone; the starch disappears with the growth of the larva and is supplanted by tannin and oil; (2) a protective zone of scelerenchyma tissue containing albuminoids and tannin. There is a gradual transition between these two zones. The supet- ficial part of the gall is made up primarily of cork cells whose contents are reduced to a thin layer of tannin deposited against the inner walls. e€ tannin exists in all parts of the gall, but is most abundant in the parts referred to above, and increases in amount with the decrease in starch. It causes a coagulation of the contents of the cells, persisting in the protective cells in the orm of grains, and in the cork cells as a thin peripheral layer. The reviewer has observed similar conditions in several of our American galls. ; Another exceptionally good piece of work is that of Houarp™ on the action of certain scale insects on the plant tissues. His studies were restricted to Asterolecanium variolosum, A. thesii, and A. algeriense on Quercus peduncularia, Q. sessiliflora, Q. pubescens, Pittosporum tobira (an Asiatic plant), Templetonia retusa (an Australian plant). In all cases these insects cause cone-sha swellings, and in the tip of each cone a depression in which the insect is located. The swellings are due partly to thickening of the bark and partly to a modifica- tion of the vascular bundles. The galls differ in accordance with the response of the vascular bundles to the stimulating influences of the insects; the more com- — pact the bundle, the greater the resistance. If the bundles are compact, the hypertrophy of the medullary rays is slight and the bundles only slightly sepa- rated, thus making it difficult for the parasite to reach any great depth. In the case of A. variolosum, the vascular bundle responds to the action of the in- sect in the formation of new wood only. This new wood possesses an abnormal structure due to the sucking of the insect interfering with the normal differentia- © Denizor, M. Georces, Sur une galle du chéne provoquée par Andricus radicts (Cynipide). Rev. Gén. Botanique 23:165-175. IgIt. : * Hovarp, C., Action de Cécidozaires externes, appartevant au genre Asteroleca- mium, sur les tissues de quelques tiges. Marcellia 10:3-25. 1911- Igt1] CURRENT LITERATURE AIL tion of the fibers. The major ‘part of this abnormal structure forms lignified cells with slightly thickened walls. In the case of T. ‘ences ~ ring of vascular bundles presents enough resistance to prevent the] yp phy of the medullary Tays. However, A. algeriense has a stronger influence on the intermediate woody vessels, stopping pin development and causing a hypertrophy of the thickened angles of the stem. The vascular bundles in the stem of P. fobira are much less resistant than in any of the preceding host plants; in this case the insect affects the bark, easily gains entrance to the medullary rays, and causes a hypertrophy which results in the separation of the vascular bundles. The modification of the tissues between the bundles is advantageous to the insect. In the petioles and midribs, the bundles do not form a complete ring and therefore are much less resistant than in the twigs, and are subject to much greater hypertrophy. In all cases, except the last, the external tissues of the stem undergo excessive hypertrophy and form the greater part of the gall. The biology of galls is ably discussed by Dr. ARTUR Mopry,” who gives a review of the subject and also the results of his own investigations. though the study of galls is very old, it has attracted comparatively little attention from: biologists. The workers on this subject have defined galls differently, but the definition given by BEYERINCK is most generally aie at the present time. According to this definition, the gall is a “new formative — within the body of the plant and is due to insects or plant organisms.’ MAS Suggested the use of the word “cecidien” (meaning nut gall) as a substitute for all other terms; then subdivided the galls on basis of cause into Phyto- cecidien and Tao cocidiats and these groups sais myco-, . ae phytopto-, entomo-cecidien, etc. Although this marked an advance in the study of cecidology, it was of very little botanical importance. This w was largely over- come by KERNER,* who suggested the following divisions: felt simple mantle ck covering solid Galls foliage bud flower compound others This division has been of great value for descriptions. In 1904 Ross sug- 8ested division into root, stem, leaf, and blossom galls. This division has been of considerable value, but was not very practical. LacazE-DUTHIERS (1849-1853) suggested division into internal, external, and mixed galls. How- ever, the greatest advance was made by KtsTER, who as a result of his study relent Mopry, Dr. Artur, Beitrige zur Gallenbiologie. K. K. Staats-Realschule. 1911. *3 KERNER AND OLIVER, The natural history of plants 2:514-554. 1895. Sechzigsten Jahresb. 412 BOTANICAL GAZETTE [NOVEMBER of gall anatomy divided them into (1) galls without cell multiplication (enlarge- ment of cells should not be confused with multiplication of cells), (2) soft galls, and (3) hard galls. The divisions are based on the character of the tis- sues of which the galls are composed. The author admits there are so many intermediate stages as to make these divisions in some cases very unsatisfactory. Monry follows KtisTEer’s divisions, and gives a very comprehensive review of the various structural (both external and internal) characters of the various groups of zoo-cecidia. A review of this part of the paper would require entirely too much space and is entirely peagueme! for those who are familiar with the literature of the histology of ga Another paper of great interest ‘e Americans is by TROTTER™ on a collection from Washington, Oregon, Arizona, California, Hawaii, and Mexico. In this paper the author describes 88 species, of which g have been described. Of the remaining 79, 13 are given specific names and the remainder assigned to genera only. This paper is a most excellent illustration of our lack of knowledge of the American cecidia. Dr. ScaLIA’ gives a very interesting discussion and description of a new species on Cyclamen neapolitanum, to which he assigns the name Phyllocopies Trotteri. One of the most valuable contributions to American cecidology in recent years is SmitH’s™ paper on crown gall and sarcoma. In his recent bulletin on crown gall, Dr. Sairu calls attention to the resemblances of crown gall o plants to malignant animal tumors, especially to sarcoma. This resemblance has attracted the attention of many workers, but it remained for SMITH to demonstrate that it is something more than superficial. The questions previously unsolved which SmitH answers are (1) the presence of bacteria in the secondary tumors, (2) the origin of the secondary tumor from the primary to which it remains attached by strands of tumor tissue, (3) the structure of the secondary tumor is the same as that of the primary. The strand of tumor tissue core: the galls works its way as an outgrowth from the primary gall, the interior of the stem and leaves. At suitable places it undergoes diigisintate forming deep seated seed galls which eventually become apparent on the surface. These tumor strands contain the bacteria which cause the disease. We are promised othe bulletin on this interesting sub- ject which we will await with great interest. Another very interesting goatee which the reviewer believes should ROTTER, A., Contributo alla Conoscenza delle Galle dell America Nord. Mar- cellia 10: 28-61. rie . figs. 21. 1911 *s ScaLia, Dr. Be = Species di Eriofide sul Cyclamen neapolitanum Ten. Marcellia 10:62-64. 1 6 Sura, ERWIN ‘ Crue gall and sarcoma. Circular No. 85. U.S. Bureau of Plant Taduatey: Igit Igtt] CURRENT LITERATURE 413 be included under cecidology, is that part of the work of East and Haves’? on inheritance in maize which refers to “ plant abnormalities.”” In this part of the work, the authors state their objects as follows: “The first object was to see whether the manner of transmission of inheritable monstrous char- acters gives any clue to the reason why monstrosities have seldom obtained a foothold in nature when in competition with normal types. The second object was commercial. If teratological specimens appear in commercial varieties of maize, it is desirable to know the easiest method to destroy them.” The authors discuss the appearance of and experiments with dwarf forms, irregular- ay of rows of seeds on cob, bifurcated ears, ears with lateral branches, plants with striped leaves, and hermaphrodite flowers. They call attention to the fact that many of these monstrous variations occur in strains that have been self fertilized for several generations, and suggest that inbreeding may give € same effect as lack of nutrients, while cross-breeding may give the opposite effect. Monstrosities are due to retardation or acceleration of cell divisions. The question is then raised as to whether the monstrosities might not be due to an abnormal distribution of the chromatin. Another paper is promised on the effects of inbreeding in maize.—MEL. T. Cook. Recent papers on Phytomyxaceae.—MaireE and Tison® have published a brief note on Tetramyxa parasitica Goebel, which produces galls on Ruppia and Zannichellia. The parasite appears in the host cell in the form of an amoeba, which undergoes division simultaneously with the host cell in such a way that at first only a single amoeba appears in each cell. During this Stage the nuclei are said to divide in the manner described by NAWASCHIN and by Prowazexk for Plasmodiophora. As these accounts differ somewhat as to detail, it may be inferred that the division in its main features follows the method common to the members of this group, by the formation of a chromatic ring around a karyosome, both of which divide. This stage is followed by the chromidial stage, during which the chromatin disappears from the nuclei and ch tic bodies appear in the protopl Later the (same) nuclei appear with a chromatin network and undergo two karyokinetic divisions, which are followed by spore formation. Karyogamy was not observed. In a second paper, Marre and Tison” describe a new genus, Ligniera, to include those species of the Plasmodiophoraceae which lack the schizogenous Stage or have it very poorly developed, and which do not cause gall formation in the host plant. By these characteristics the genus is separated from the genera ? East, E. M., and Hayes, H. K., Inheritance in maize. Conn. Agric. Exp. Station, Bull. 167. pp. 129-137. IQII. *® Marre, RENE, et T1soN, ADRIEN, Sur quelques Plasmodiophoracées. Compt. Rend. 150: 1768-1770. I9I0. **——.. Sur quelques Plasmodiophoracées non hypertrophiantes. Compt. Rend. 1§2: 206-208. rgrr. 414 BOTANICAL GAZETTE [NOVEMBER Plasmodiophora, Sorosphaera, and Tetramyxa. The new genus includes L. radicalis, which is new, L. Junci (Schwartz) (Sorosphaera Junci Schwartz), and L. verrucosa, also new. OsBORN” gives an account of the development of the interesting form Spongospora subterranea, causing the corky scab of potatoes. Penetration of the organism into the host cell was not observed, nor was it possible to infect sound potatoes with spores. The first stage observed consisted of an amoeba containing a single nucleus, which had a membrane, chromatic gran- ules, and a deeply staining karyosome. In the early stages nuclear division is followed by division of the amoeba, so that a number of independent amoebae are found in the same host cell. The parasites occur in the cambium, and when the parent cell divides, one or more amoebae are included in each daughter cell, in the manner described by NAWASCHIN for Plasmodiophora, and by BLOoM- FIELD and Scuwartz for Sorosphaera. The division of the nuclei during this stage is of the type characteristic of the group. The chromatin forms a ring around the karyosome; both the ring and the karyosome then divide, and the halves move toward the poles, where the halves of ring and karyosome unite into a deeply staining mass. The nuclear membrane constricts between the masses, and finally divides at the point of constriction, leaving each chromatic mass enclosed in a separate membrane. No fibers or polar radiations were observed. At a later stage many of the amoebae are multinucleate, and when the food content of the host cell is exhausted, the amoebae coalesce to form a plasmodium. At this time the chromatin of the nuclei disappears and chro- matic material appears in the protoplasm. When the nuclei appear organ- ized again, they contain a chromatin network but no karyosome. The author is inclined to believe that the new nuclei are constructed de novo. This stage is soon followed by fusion of nuclei in pairs, and a period of nuclear growth previous to spore formation. Two karyokinetic divisions take place, after which the protoplasm is rounded up into uninucleate spores In a later paper Marre and Tison*' give the results of further observations on Sorosphaera, Tetramyxa, Ligniera, and Mollierdia, some of which differ in some points of their development from other forms of this group. Teéra- myxa parasitica has multinucleate plasmodia during the phase representing e schizogenous stage, the nuclear divisions not being accompanied by ¢ | division. The chromidial stage, prominent in other forms, is lacking here. At the secre of spore formation, me plasmodia break up into uninucleate masses. result of two mitotic divisions, and divide by constriction into four uninucleate spores. In this form, 45 * OsBorn, T. G. B., Spongospora subterranea (Wallroth) Johnson. Ann. Botany 25 1327-341. pl. 27. 1911. * Marre, René, et Tison, ApRIEN, Nouvelles recherches sur les plasmodiopho- races. Ann. Myc. 9:226-246. pls. 10-14. fig. 1. IgIr. grt] CURRENT LITERATURE 415 well as in Sorosphaera, amoebae are carried into new cells by the division of the infected host cell as described above for S ‘pongospora, igniera radicalis develops in the root hairs and cortical parenchyma of the . Toots of Callitriche stagnalis. As stated in the former paper, a true schizoge- occurs here as usual before the meiotic divisions. The first of these divisions often occurs before the plasmodium has broken up, but in such cases the plas- modium breaks up into “energids” during the second mitosis in such a way that the four nuclei resulting from the two mitoses are inclosed in the proto- plasmic masses, which break up into four spores. The mode of development of L. Junci and L. verrucosa is similar to that of L. radicalis. Molliardia is described as a new genus to include Tetramyxa Triglochinis Molliard. This form is peculiar in producing no spores on the host plant. infected cells contain plasmodia which soon break up into uninucleate schizonts. These become 2-8-nucleate and break up anew. The full life history of this form is not known. In conclusion, the author adds some observations on the affinities of the Plasmodiophoraceae. He is inclined to regard them as being more closely related to such forms as Rhizomyxa and Woronina among the Chytridiales than to the Myxomycetes.—H. HASSELBRING. The Grigna mountains.—The Grigna group of mountains includes some 60 square miles of mountainous country. in northern Italy, adjoining the eastern shores of Lake Como and the connecting Lake Lecco. Its phytogeo- 8taphical description by GErILINGERE* has an additional American interest because of the location of the region near the main route of American tourist travel. Notwithstanding its small area, the elevation varies from 199 meters _ at Lake Como to 2,410 meters on the highest of the peaks. This permits a wide range in climate, which is of course reflected in the vegetation. The Mediterranean province does not reach so far north, but many species of Mediterranean origin are present, and the olive extends to a maximum altitude of 490 meters. Most of the area is comprised within the submontane region, With forests of oak, hop hornbeam, and chestnut extending up to 1os0 meters. From this elevation to 1650 meters the montane beech forests dominate. €se in turn are succeeded by the subalpine forests of larch as far as 1950 meters, above which is the treeless alpine region. For all of these regions the author distinguishes ecological groups with a detail seldom approached in America. He recognizes seven chief types of vegetation, including forest, bush-forest, perennial herbs, grassland, swamps, aquatic vegetation, and rock vegetation. These are subdivided into formational groups, formations, and Societies, of successively minor importance. This classification is d * GEILINGERE, G., Die Grignagruppe am Comersee. Bot. Centralbl. 247: 119-420. 416 BOTANICAL GAZETTE [NOVEMBER primarily upon physiognomy, and only secondarily upon environment or floristic composition. It is doubtful whether such a method can ever give entirely satisfactory results, although the author considers it the best for this region, where all the associations show the effect of cultural changes. Probably the gravest defect of the paper is the entire failure of the author to discuss the dynamics of the vegetation. The development of the various associations and their successional relations are omitted completely. Illustrations would have added greatly to the clearness of the descriptions, and the scale of the accompanying map would have easily permitted the location of the chief types of vegetation. Almost half of the ate article is occupied by a care- fully annotated list of species—H. A. GLE ; Gametophytes and embryo of Pseudolarix.—MrvakeE and YasurI* have investigated the monotypic Pseudolarix (P. Kaempferi), a native of China, one of the Abietineae whose morphology had not been studied. The material was obtained from a tree growing in a garden in Pallanza, Italy. The winged grains contained the usual cells of the male gametophyte, and the divisions showed 12 chromosomes, but the later development of the game- tophyte was not seen. Megaspore formation was observed, a linear tetrad being formed about the time of pollination (April in Italy). The large central vacuole is formed in the spore stage (before free nuclear division), and the young female gametophyte is invested by several layers of nutritive cells. At maturity, the megaspore membrane is well developed, as in other Abieti- neae. Early in June the female gametophyte is solid tissue, and then the § or 6 archegonium initials appear, the archegonia maturing in about three weeks. After the division of the central cell, the ventral canal cell disorganizes at once. Fertilization occurs about the end of June, and the first four free nuclei of the proembryo move to the base of the egg, walls appearing with the — next division. The cells of each tier divide, and the completed proembryo consists of four tiers, with four cells in each tier. The functions of the tiers are as in Pinus, and the whole situation seems to be an almost exact duplica- tion of that genus.—J. M. C A cedar bog in Ohio.—Dacunowskr* records, as an isolated area of northern plants, left behind in the great northward migrations following upon the retreat of the ice sheet of the glacial period, a swamp in central Ohio, characterized by Thuja occidentalis and other species not usually found south of central Michigan. Mats of sphagnum, together with the sundew and various orchids, testify to the true bog character of the association —Gro. D. FULLER. 3 Mixayi, Kiicut, and Yasur, Kono, On = oe and embryo of Pseu- dolarix. Ann. Botany 25:639-647. pl. 48. 1 *4 DACHNOWSKI, ALFRED, A cedar bog in AOE Ohio. Ohio Naturalist 11: 193- 199. IQII. THE BOTANICAL GAZETTE December ro9xr Editor: JOHN M. COULTER CONTENTS Light Intensity and Transpiration Burton Edward Livingston The Embryo Sac of Epipactis William H. Brown and Lester W. ee The Oxygen Minimum and the Germination of Xanthium Seeds Charles Albert Shull Briefer Articles A Protocorm of Ophioglossum W. J. G; Land Current Literature The ‘University of Chicago Press be geaiae ay ILLINOIS _ THE CAMBRIDGE UNIVERSITY PRESS, London and Edipbursh WILLIAM WESLEY & SON, L ondon oe: "TH, STAUFFER, Leipzig THE -MARUZEN- KABUSHIKI-KAISHA, peat ae Osaka, Kote The Botanical Gazette A Monthly Fournal Embracing all Departments of Botanical Science Edited ps Joun M. CouLTER, with the assistance of re. members of the botanical staff of the University of Chica Issued December 19, ni Vol. a | Sent FOR DECEMBER 1911 No. 6 LIGHT 1 INTENSITY AND: TRANSPIRATION (wits OnE FIGURE). Burton Edward Livingston 417 | THE EMBRYO SAC OF EPIPACTIS (wits priate x). William H. Brown and Lester W. Sharp 439 THE OXYGEN MINIMUM AND THE GERMINATION OF XANTHIUM SEEDS. Con- TRIBUTIONS FROM THE HuLt BoTanrcAL LABORATORY 152 es ONE Hee: Charles Albert Shull - > < = se Pi - BRIEFER ARTICLES 3 Be prs OF OpHIocLossum eae ONE FIGURE). W. J. G. Land - - - -. 478 = CURRENT PEEVE: 7 oe _ MINOR NOTI So ee a Be ee _ NOTES FOR iis De ee Res a eee ee ee ie ae as 480 The Botanical Gazette is $ published monthly. The eitiadon price is $7.00 per year; the price “ eee opis bee 75 cents. Postage is prepaid by the publishers on orders from the United States, . oe : sto Rico, Panama Cana one, Republic of. Panama, Hawaiian Islands, ‘Philippine Islands, Guam, Tutuila (Samoa), Shai i Postage is charged extra a él ows: For 35 cents ptions (total $7.35), on single copies, 3 cents (total 78 cents); for all other countries in the ostal ‘Union, 84 cents on annual subscriptions (total $7.84), on single copies, 11 cents (tot 86 cents). ae se- ould be made payable to The University of Chicago Press, and should be in Chicago or ge ee eee or express money opdes, “LE tocal he is used, 10 cents must be added for The fo ollowing agen’ a he es appointed and are authorized to quote the prices indicated: a _ For ee oes Empire: The bridge University Press, Fetter Lane, London, E.C., and William Wesley -& Son ex Street, Seas, oe Yearly acai cae including postage, £1 125, 6d. 5 7, ned Sie odie postage, 39. 67. e oe! 1¢ Continent of Europe: Th. Sta utr pinicdebas 26, Eos. Germany. Yearly sub- ‘iptions, 3, Including | pee ee. 33 each; single copies, i cama postage, M. 3. io : For Jap an and Korea: The Maruzen-Kabushiki-Kaisha, 1 eNikoah bashi T coe chome, Tokyo, ae vents y subserptions, ees! pone hss 15. 75 S each; single copies, Gacliciing postage, Yer 9 within th lar month of abli- Pieaeyg: The pbk shat to soph s missing ‘uumbers hss Potties fete Been iets im tans usiness addressed to The University of Chicago Press, Chicago, air unicat tions for état should be addressed to him at the University of Chicago, ap es Tl. ributors are requested t 0 write scientific and proper names with particular care, to use the metric nes and aca gis and i in. diene: % follow a ret shows in the pages of the BOTANICAL Sj ages excess 5 of thirty two. print ted pages are hot accepted atte the author is willing to pay the og addition ial pages, im whch tase the number of pages in the volume is correspondingly increased. lout cost te author only when rey onarees are 8 supplied. A copy ere a number, 1907, will be sent o ie oh tion. It is advisable. to ilustratio is required i in any article to be offer be ordered in advance of ee ation. tae enty- five aie of original *PP ied pk ae es fale s owing approximate cost of additional arg tes ni ace pees ugly wn Be deme an rosiee” ae class matter, under Act o! Moffat, Yard Moffat, Yard and Company and Company IMPORTANT FALL BOOKS MEMOIRS | OF _ THEODORE THOMAS E FAY TH ll pian 8vo, Ne ae net of aR nee say ee he te yet te) poe ree aoe ot and ferees by De shies belo cee GENIUS AND. OES ESSAYS By EDMUND CLARENCE STEDMAN. ted by Laura Stedman and George M. Gould 65 o, $1.50 net. By mail, $1. 8vo A collection of distinguished essays culled from the great body of material, the work of his maturity, left by Mr. Stedman at his death. THE GIFT OF SLEEP By BOLTON HALL. With an introduction by Professor Edward M. Weyer, ideo cic and Jefferson College o, $1.25 net in This very interesting work shows how our own pa and minds should be naturally used for their mutual heal- gand perfection. It is for the layman as well as the scientist. DR. JOHNSON AND FANNY BURNEY Being oe Johnsonian Extracts From the Diary of Madame D’Arblay y CHAUNCEY BREWSTER geese bles D., of Yale University Illustrated. $2.0 The extracts from the diar y of Madame d’Arblay relating to 85 paul friendship with the great lexicographer. They have never before appeared in separate form. FATHER ping cys The Black Robe Voyageur HARINE HUC "aaa esp hhcriciiaa $2.5 seam tia ee Hn ia anit, Ace SOME OLD FLEMISH TOWNS By GEORGE buiouter ch 3 EDWARDS, author of “Holland of To-day” and “ retons” rittany of the B Elaborately illustrated with six full oe Part and 32 monotones by the author. Beautifully bound and decorated. Boxed. $4.00 net. Carriage extra This rich book of travel ranks, in informative value and interest, with the author’s “Holland” and “Brittany.” TWO YEARS IN THE FORBIDDEN CITY By PRINCESS DER-LING (Mrs. Lannea C. White) Iilustrated. Svo, $2.00 irst tak Waiting to the late Empress Dowager - exceedingly interesting narrative oft the experiences of ~ Fi rance, where she was educated. of China. The Princess is the daughter of a C oF THE LIFE, TRIAL, AND DEATH OF F RANCISCO FERRER By WILLIAM ARCHER Illustrated. Large 8vo, $3.00 net ‘e A thorough and impartial account e — famous radical and thinker whose execution in Spain caused a great nsation in Europe and America a year rar. OF Bi (MARKET 0, tage senti A practical solution of the Trust Problem. in book Aa the hg a solution which would result in an industrial pea ‘ principle of State Control convincingly, pre- MOFFAT, YARD AND COMPANY, Union Square, New York — Some Baker & Tay ; | vlor Co. Fall Books FICTION VICTOR L. WHITECHURCH seca dl of Bin apo t in Residence Con mself. A _ strong RO ae n cel whieh owe the hero a lifelon; = friend o the reader. 380 pages. Net $1. Postage, 12 cents. Off the Main Road. The story of a scholarly recluse and the —* — brings him back into ry current life, 2mo. 320 pages. Net $1. haeraay: 2 = cents. MABLE BARNES-GR bg d Mi enderby. The Thir Ss y. Aromance of a quie' a t deeply moving cope, wi with a charming heroine and happy ending. 12mo. ey eon 350 pages. Net t $1.25 a to ce F. E. CRICHTO The A story of bedi ae I2mo. decutlees ane: 340 pages. Net $1.20. ROY ROLFE GILSON Ember Light. The story of a home, the ideals it a. Ber those which were sacrificed for it. r2mo. pages. Illustrated. Net $1.30. Post- age, 12 > omte LEAN GREE — of “Cape Cod Folks Green Road. The record ofa rare friend- Postage, 10 cen NE ks” ng ship. r2mo. _ pages. Frontispiece. Net $1.25. Postage, 12 cen : PERCY J. HAR’ The Hand gee A story of love, adventure, and fighting in the days of sae. Fag II. r2mo. 340 pages. Net pon 20. Postage, ro cents. GEORGE H. JESSOP Where the Shamrock Grows. full ip bayer wit = Arse oi ‘ostage, I An ay Bessemer, I2mo. pa A story of friendships at a t2mo. 325 pages. Illus > ae Noble Ives. Net $1.25. Postage, POETRY BERTHA GORDON ngs of Loney he The poems of a true singer. ee 72 pages. Boards, male labels. Frontis. Piece portrait. Net $1.00. Postage 8 cents. sak CAR Hard Labor and Other Poems. tional and msamegg 6 i beweet mow $1.00. Postage, 8 JOYCE KILMER Summer of Love. t2mo. Cloth. go cents. Poetry of emo- T2mo. 96 pages. aes t Poetry of imagination and charm, pages. Net $1.00. Postage, 8 SIR GEORGE DOUGLAS, Bart. Scottish Poe Contains th Scotland. = gg 928 pra Cloth. 18 cents. 1s — paper edition, HOLIDAY HELEN A. CLARKE : The Poet’s New England. Records the charm of New England —— which have been celebrated by the poets. with Hawt. port $s country and Longfellow’s Le oars. 8vo. 350 D . Fully illus- rete es in jh ean Net $2.50. Postage, 18 cents pan ec ogh ae sage eggs NE Rossetti and ae hs als spo Queen of Scots an Chastel si — a, George Sand and Chop’ Fully illustrated, with, portraits, Sersnneiee orders, end papers, by W. W. Fahnestock. t $1.50. Postage, 15 cant. JUVENILE EDWIN TENNEY BREWSTER A Child’s Guide to Living Thin An account in — and yrogage ‘prose of tie familiar forms esses of life. o. Fully illustrated. Net "Pome: 12 cen GEORGE HODGES, A Child’s Guide to ae Bible. — to the — I2mo. ge, 12 cen A sympathetic intro- Illustrated. Net $1.20. LEWIS CARROLL Alice in Wonderland. Illustrated by George Soper. seni with Tales from Shakespeare, Kin ss ley’s Water Babies. Square 8vo. many illustrations in color and ii CLIFTON compe Editor of b hag se. Contains the world- for cong ad reading. Uni- bs with Robie poetry Arabian Nights, etc. 1I2mo. © pages. Illustrated. Net $1.00» "hontax e, rocents. Mother Goose. A charming version. ak as a she page in gions Nene ar bee i i a Square 8vo Tilustra: in avon with in veg end saa ple by \ Will, Bradley and others. et $1.25. Postage, 15 ¢ MISCELLANEOUS JOHN FORSTER Life of Charles Dickens, Centenary Edition. _ Splen- didi and profusely paige hg with over 500 ant vols. Imperial 8vo. et $7.00. Carriage WILLIAM ao. The Women of Tomorrow. An incisive and bril- liant Sronbenent rat thechanges in the ares so women. Fully illustrated. t $1.50. I2mo, 300 pages. Postage, 14 cents. REDFERN ed SON The Song Lore of Ireland. New edition. The 8vo. 321 pages. Net $2.00. meaning o pid music. ILLUSTRATED HOLIDAY CATALOGUE AND PORTRAIT CATALOGUE SENT FREE ON REQUEST The Baker & Taylor Company, 33 East Seventeenth Street, New York 12 VOLUME LII NUMBER 6 guises BOTANICAL CAZETTE DECEMBER 1011 LIGHT INTENSITY AND TRANSPIRATION*™ BurRTON EDWARD LIVINGSTON (WITH ONE FIGURE) Introduction While it is well known that light intensity plays an important role in the determination of water loss from plants, our knowledge of this matter is purely qualitative. The present paper deals with an attempt to find some simple means of physically determin- ing the intensity of solar radiation with reference to its effect on plant transpiration. While the results to be here brought forward do not possess that degree of completeness that we are wont to expect in the fields of physics and chemistry, yet they emphasize the quantitative aspect in the study of the external factors which influence plants in the open, and they seem to place in the hands of ecologists of a quantitative turn of mind a somewhat ready means of approximating the physical magnitude of one of the most im- portant, and at the same time most baffling, of the environmental conditions with which they have to deal. The total amount of transpirational water loss from a plant, for any given period, may be considered as a summation of the effects of the evaporating power of the air and of the radiant energy absorbed throughout the period, modified by certain secondary ‘Botanical Contribution from the Johns Hopkins University, No. 21. * The pressing need for methods of evaluating the various external factors which affect plants has been emphasized in a paper read before the Botanical Society of merica in 1908. See Plant World 12:41-46. 1909; and Amer. Nat. 43: 369-378. 1909. 417 418 BOTANICAL GAZETTE [DECEMBER effects of these conditions and by certain responses to other con- ditions. One secondary effect of variations in light intensity is seen in the opening of stomata when many plants are transferred from darkness to diffuse or stronger light. These openings close, or tend to close, in many plants when light gives place to darkness or to very dim light. But there seems to be no evidence for thinking that stomatal movement is at all marked as long as the intensity of illumination is above a certain minimum, about what is known as weak diffuse light. Of course they close with wilting under any light conditions (see Ltoyp, Publ. 82 of the Carnegie Institution). Another secondary effect of high evaporation conditions, whether caused by direct sunlight or by dryness of the air, etc., is the removal of water from the leaves at a rate more rapid than its rate of entrance, so that the cells are plasmolyzed and general wilting occurs. It is probable that this effect is felt long before actual wilting is to be observed; whenever transpiration surpasses the rate of water supply to the transpiring tissues it must be supposed that a gradual lowering of the vapor tension of the water films held in the moist cellulose walls will ensue, just as a semi-dry piece of filter paper will exhibit a much lower vapor tension than a similar piece saturated. Long before plasmolysis occurs we should expect to find that the capillary menisci of the cell membranes abutting upon the internal atmosphere of the leaf would become more and more concave, and would perhaps break and retreat into the pores of the membrane. In the one case, the vapor tension of the water film, in the other their actual superficial extent should be reduced. It may thus come about that an increase in the evaporating power of the air or of solar insolation might produce, by its very accelerat- ing influence, a retardation in the transpiration rate. Such a phenomenon is common in soils, where an increase in the rate of water loss above the rate of diffusion of water to the soil surface causes the water films to retreat into the soil and thus decreases the rate of water loss. It is thus that the “dust mulch” is produced, _ by which adaptation the soil seeks to reduce water loss in a dry time! A measurable falling off in the relative transpiration rate, occurring in the forenoon, when the evaporating power of the air and the light intensity are both still increasing in their daily march, t911] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 419 is exhibited in certain of the transpiration graphs of Publ. No. 50 of the Carnegie Institution. These occurrences may well be due to the phenomenon just suggested, which may be termed incipient wilting. If the process were carried far enough, actual wilting would of course ensue. If incipient wilting be the true cause of this sort of fall in transpiration, without any appreciable stomatal closure, it should make itself manifest by a gradual fall in the gross water content of the leaves themselves, which should be- come more marked as evident wilting was approached. It is seen, then, that either stomatal closure or this hypothetical in- cipient wilting must act to decrease the equivalent evaporating surface of plants. By equivalent evaporating surface is here meant a free water surface which would evaporate the same amount of water as the plant, at the same place and for the same period. Since the secondary effects of variations in light intensity through the photosynthetic process may be safely regarded as negligible in the present state of our inquiry, they will not be considered here. We may therefore assume that (for short periods having light intensities continuously adequate to prevent the closure of stomata, and with transpiration rates and a moisture supply which do not produce incipient wilting) the plant is virtually to be looked upon - 4S an integrating atmometer, automatically summing the various increments of water loss from moment to moment as these fluctuate in magnitude. It might therefore be expected that a physical atmometer exposed at the side of a plant should exhibit the same march of the evaporation rate as that evidenced in the transpiration of the plant, providing of course that suitable corrections of the observed rate be applied, to adequately account for any and all internal changes in the organism which were influential in reducing the effective or equivalent evaporating surface of the latter. It is On this general supposition that the methods used in this study are based. To keep logically and spatially within bounds, I shall here con- sider the effects of changes in the intensity of illumination between Strong diffuse light and direct sunshine, thus once for all avoiding the question of marked stomatal movement. The stomata in my 420 BOTANICAL GAZETTE [DECEMBER experiments are supposed to be open, in the day condition, through- out. I shall also limit my considerations to short periods of time, at least to short periods in strong light, thus aiming at an avoid- ance of the problem of incipient wilting as above set forth. The former of these problems has been touched upon already (see Science N.S. 29:269-270. 1909), and the full consideration of it should make another title. The second problem, of incipient wilting, cannot be experimentally considered at the present time. The specific problem which now holds our attention is, then, Is it possible by any simple means to estimate quantitatively the various light intensities to which plants in the open are subjected and so to sum the effects of these as to be able approximately to calculate the variations in transpiration thus brought about, and the total transpiration for the longer period in which these varia- tions occur? It is obvious that the solution of such problems as this is of the utmost importance in establishing a basis for a scien- tific agriculture. Also, such problems lie at the bottom of con- siderations of the factors determining plant distribution, and it must be through their solution that ecology may at length emerge from the descriptive and classificational stage in which, for the most part, it now finds itself. The importance of our present inquiry is exceeded only by its difficulty. Apparatus and methods To attack the problem outlined above it was necessary to meas- ure the water loss from experimental plants under different light intensities, and to compare the various rates thus obtained with readings taken, for the same periods and exposures, upon whatever physical instruments were available for the estimation of light intensity. For the plants, the ordinary method of weighing potted and sealed specimens was resorted to. A number of different instruments for determining light intensity were tested. I shall proceed first to a discussion of these instruments. : Since the intensity of solar radiation varies from time to time, even for short periods, as on a partly cloudy day, our great desider- atum in the present connection is an instrument or method for automatically obtaining an integration of this factor for a given 1911] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 421 time period. One such device was available at the inception of this work, another was devised. 1. The Hicks solar radio-integrator (obtainable from J. Hicks, Hatton Garden, London) consists of a glass vacuum chamber, the upper portion of which (a spherical bulb) is about half filled with dark-colored alcohol and exposed to the light. The alcohol vapor produced by the absorption of energy by the dark surface is con- densed in a lower bulb and collected in a still lower burette-like, grad- uated tube. The condenser and receiver are shaded during opera- tion, and readings are obtained from time to time on the amount of alcohol distilled into the tube. The instrument is occasionally to be inverted and the collected alcohol replaced in the exposed bulb, an operation made possible by a bent tube connection between the two bulbs. The rate of distillation depends of course on the difference between the vapor tension of the alcohol in the upper bulb and that obtaining in the shaded part of the apparatus. The shaded part nearly maintains the temperature of the surrounding air, while the exposed bulb tends to be warmed by the sunshine. Thus this instrument causes the sun’s rays to perform work in vaporizing alcohol and furnishes a means of measuring the work accomplished in terms of the amount of the liquid accumulating in the graduated tube. It is thus seen to be self-integrating. 2. Various lines of experimentation had shown that the porous cup atmometer, a self-integrating device for estimating the evapo- rating power of the air (see Publ. No. 50 of the Carnegie Institu- tion), is measurably affected by sunshine; that, celeris paribus, it loses more water in direct sunlight than in shade. The differ- ence in rate so produced, however, is not as great as that observed in plants under the same varied conditions of illumination. Con- sidering this fact, it occurred to me that it should be possible to modify the porous cup in such manner as to cause it to absorb a greater proportion of the sun’s energy, and thus render the ratio of its readings in light and shade more nearly like those obtained from the plant. The instrument already integrates the influx of energy, in terms of the amount of water evaporated, and the con- templated alteration should involve only the coloring of the porous evaporating surface so as to increase its power to absorb radiant 422 BOTANICAL GAZETTE [DECEMBER energy. After numerous preliminary tests this possibility was achieved. The porous cups are now furnished in a dark-colored claves deep, grayish brown, and these cups show a marked increase in light-absorbing power over the ordinary white ones. 3. Another light-absorbing cup was obtained by coating the white form with a thin layer of washed lampblack. Common lampblack is boiled in distilled water, allowed to cool and settle, and the water decanted as well as possible. This process is repeated three to five times, and furnishes a clean, insoluble, and impalpable black powder, in the form of an aqueous paste. The latter may be diluted and applied to the cups with a small brush. This applica- tion should be made after the cup is filled and ready for operation, as the absorption of water by the surface when thus arranged is sufficient firmly and quickly to fix the carbon layer in place, and the latter is never allowed to become drier than it is destined to be in the actual operation of the instrument. The cup cannot be handled by the coated surface without injury, but it is a simple matter to renew the coating if such injury occurs. These coated cups operate in essentially the same manner as the permanently colored ones. used in these tests, the white, brown, and black cups were in- stalled on burettes, essentially as figured in Publ. No. 50 of the - Carnegie Institution. 4. The black bulb thermometer im vacuo (the one used was obtained from the Kny-Scheerer Co., New York) is essentially an ordinary glass-mercury thermometer, the bulb of which is blackened and inclosed in a thin glass vacuum bulb. It is exposed to the light for a short time period and the rise of the temperature of the bulb noted as the reading. The instrument must be shaded and must come to air temperature between observations. It is seen that the light absorbed by this instrument is made to do the work of expanding the mercury, the amount of expansion occurring in a specified time being the measure of the energy absorbed. The devices for light estimation thus far mentioned all depend upon the heating effect produced by the absorbed light. Another group of instruments, all following the principle of the Bunsen- Roscoe “photometer,” depend upon the chemical effect produced tgt1] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 423 by the absorbed rays. These instruments now make use of some form of photo-sensitized paper, and the reading is either the length of time required to produce a certain standard shade of color in the paper, or the depth of color produced by an exposure of a certain length. WresNER’s instrument (see his Lichtgenuss der Pflanzen) belongs to this class. They are not photometers in any true sense, but really actinometers, measuring only the actinic effect of the light. The paper may be modified so as to give sensitiveness in any part of the spectrum, but the region to which they are sensitive is always rather limited, and the sensitiveness is not uniform through- out this region. Another obstacle in their operation comes from the difficulty of procuring proper standard colors; a third arises from the fact that the comparison of the color produced with the standard depends to a great extent upon the observer’s judgment, the sensitiveness of his retina, etc. Two forms of actinometer were tested in this work. They were exposed to the action of the light till the sensitive paper attained the shade of the, standard, the record being made in seconds. 5. The simplest form of actinometer for our estimations is the ynne exposure meter, for sale by most dealers in photographic goods. It is very convenient to use, the paper therefor is appar- ently carefully standardized, and with each package of paper is furnished a slip of non-fading standard color suited to that partic- ular lot of paper. 6. The other instrument of this class to which we had recourse is the Clements actinometer, a modification of the Wiesner type of instrument, using any form of photographic paper which the user may wish. It is described by CLEMENTS in his Research methods in ecology. As there recommended, I used “‘solio”’ printing out paper, and made my own standard color (water colors, afterward var- nished), which was no easy task. As will be shown in the records of these tests, there is no doubt that this method is as satisfactory in operation as that of the Wynne, but the former is somewhat More difficult. I have had evidence, moreover, that the “‘solio” brand of paper is rather more apt to alter with age (at least in a warm climate) than the Wynne paper. Since all of these instruments, both thermal and actinic, depend 424 BOTANICAL GAZETTE [DECEMBER for their records upon the absorption of incident radiations, it is essential that the angle of incidence of the impinging light be always the same. But the direction of incidence of the sun’s rays is constantly changing throughout the day, and varies, for the same hour, from day to day. It is therefore necessary to consider this matter in the operation of any and all forms of absorbing instru- ments. The Hicks instrument cannot be adjusted in this regard, for the main absorbing surface is the meniscus of alcohol in the upper bulb. The porous cup atniometer possesses a cylindrical absorbing surface, modified slightly at the closed end of the cup, which latter part may readily be removed from operation by a suitable covering if desired. Iam convinced that the error involved from the curved end of the cup, however, is negligible in this sort of estimation. The form of cup used was the usual one, the modification recently described by Transeau (Bot. Gaz. 49:459. 1910) would no doubt be as efficient for our purpose. To receive the sunlight always at the same angle, the cups are so placed that their long axis is perpendicular to the direction of light incidence at noon, the common plane of sun and cylinder being vertical. When so arranged the sun virtually rotates about the cup, its rays always illuminating one-half of the surface only, and falling always verti- cally upon a longitudinal line through the center of the lighted area. The position of the lighted area on the cup is constantly changing, but since all sides of the cup are supposedly equivalent, this introduces no complication. The position of the instrument will of course vary with the sun’s altitude, that is, with latitude and season, but may readily be determined from an almanac or by simple observation at high noon. Actual tests showed clearly that the vertical cup, as ordinarily used, fails to record proper intensities of sunshine at and about noon, for at that time only a small portion near the tip receives perpendicular radiation. Of course in high latitudes the vertical position would not introduce so great an error as nearer the equator, and the error in winter would be less than in summer. The black bulb thermometer is to be exposed in the same way as the cups. The photographic papers were always exposed by hand, so placed ott] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 425 that they received perpendicular rays from the direction of the sun at the time of observation. As to the portion of the entire radiation which is absorbed by these various instruments, it is possible to say very little at the present time. It is fairly certain that portions of all the various wave-lengths of light, as well as of the infra-red and ultra- violet, are absorbed by the thermal instruments. On the acti- nometers we may be as certain that little effect is produced outside the actinic rays. Since the heating effect is the one which we are interested in at present, because our inquiry deals with the evaporation of water from green leaves, it is obvious that on a-priori grounds the thermal instruments are to be regarded as the most reliable. The quantitative statement of this whole matter must be left to some future time. One other theoretical point may be mentioned here with refer- ence to the interpretation of the results obtained with these instru- ments. It must be borne in mind that other factors besides radia- tion intensity are active in the control of evaporation, both from the Porous cup and from the plant. Thus, in the night time the evapo- ration rate and that of transpiration are by no means mil, while the readings of the instruments which do not deal with evaporation will vanish at that time. From this fact we may expect the differ- ences between two light intensities as shown by the non-evaporating instruments to be much greater than those shown by the evaporat- ing ones. The latter always record the rate without light influence plus that due to light, the former can show no rate without the influence of radiant energy. It is possible so to manipulate the Porous cup as to obtain readings from it directly comparable to those from the black bulb thermometer, but this cannot be entered into here. Experimentation It was my good fortune to be able to spend the summer of 1910 at the Desert Laboratory, Tucson, Arizona, under auspices of the Department of Botanical Research of the Carnegie Institution of ashington. During this period, and with the assistance of Dr. Witi1am H. Brown, now of the Michigan Agricultural College, a number of lines of inquiry which had been previously begun were 426 BOTANICAL GAZETTE [DECEMBER continued, the matters considered in the present paper forming a portion of our operations. Without the enthusiastic cooperation of Dr. Brown, the amount of experimentation and other work accomplished would have been much smaller, and the quality less satisfactory. In the three series of tests to be presented, the plants stood upon . a table in the open, the instruments being arranged in their imme- diate vicinity, so that the whole group of plants and instruments occupied a space perhaps 40 or so cm. square. Reduced light intensities were obtained by placing over the group, at a height of something less than a meter above the table, a cloth screen about a meter square, supported by a light wood frame and four light wood supports at the angles, The screen was always so placed that all the objects of the experiment were well within the shadow; they never received any direct sunshine while the shade was in position. The burettes of the atmometers and the tube of the radiometer projected below the table, so that the active portion of all instru- ments was always at approximately the same height from the table (and distance below the screen) as the plant foliage. The plants were 10-20 cm. in height; they had been lifted from the open soil several weeks previously and had been carefully accustomed to full sunlight. All had grown appreciably since potting, were leafy and apparently in good condition. They were in tinned sheet iron cylinders, some 8 or 10 cm. in diameter and about as high, - which, during the experiments, were sealed by the application of prepared modeling clay over the soil surface and over the drainage openings at the base. The plants were weighed and the instruments read at intervals of one-half hour, or as nearly so as possible. Where the time period was greater or less than 30 minutes, the data have been corrected to this time period. Weighings were made in the house, each plant remaining out of its proper position only long enough for this operation. In every test, after two half-hour periods of sunlight, there followed two similar periods under shade, these being in turn followed by two more periods of sunshine. The black bulb thermometer was covered most of the time by a loosely fitting cylinder or sheath of asbestos board, open at both ends to Igtt] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 427 allow air circulation. When a reading was to be taken, this sheath was removed far enough to expose the scale, and a reading of the shade temperature was taken. Then the sheath was completely removed and the rise of temperature which took place in a single minute was noted. The photographic instruments were operated by exposure in the hand, close to the plants, a stop watch being used to determine the length of time needed to produce darkening of the sensitive paper to the degree of the standard color, a bit of which was attached to the case of the instrument, directly adjoining the exposure opening. All instruments and plants had been in full sunshine for an hour or more at the beginning of an experiment. Wind velocity was taken, and shade temperatures, but since these data show no relation to the resulting transpiration ratios, they need not be reproduced here. Throughout the tests there was always some air motion and never a high wind, the velocity varying from ©.2 or 0.3 to 2.0 or 3.0 miles per hour. The temperature varied from about 30 to 35°C. The plants used were Physalis angulata L. var. Linkiana Gray, Xanthium commune Britton, and Mar- tynia louisiana Mill. They will be referred to merely by the ' generic names. , Results The first series of observations extended from 8:00 A.M. to 1:00 P.M., August 9, r910. A plant of Physalis, one of Xanthium, and the three porous cup atmometers (brown, black, and white) made up the series of objects. During the second hour the shade used was of white “‘8-ounce cotton duck” or tent canvas. During the fourth hour the shade was of a single thickness of ‘‘cheesecloth.” The data from this series are given in table I. To study, in a general way, the comparative effects of shade on the rates of water loss of the different objects, it is expedient to reduce each series of figures to relative values. We may take the datum for period 4 as unity in each case, and form the new series by dividing this datum into each of the remaining data. Graphs of these derived quantities are given in fig. 1, all of them passing through the common point (unity) at period 4. These graphs are thus directly comparable as to the relative heights of their ordinates 428 BOTANICAL GAZETTE [DECEMBER The periods of shade are denoted on the graphs by a broad black line below. The graphs show merely a general and qualitative agreement between the rates of water loss from the various objects. It is quite evident that the white cup fails to show nearly as great fluctua- tions with light and shade as do the plants. On the other hand, the brown and black atmometers agree fairly well with each other ‘TABLE I LOssES PER 30 MINS., GRAMS OR CC. PERIOD EXPOSURE Physal. Xanth. Brn. atm. | Blk. atm. | Wht. atm. eee Open Pe 3-4 2.9 3-7 2.0 ee te Open 3.0 4.2 4.3 4.7 2.8 Sse Canvas shade “7 2.4 4.2 3-4: 2.4 £05 Canvas shade 1.7 2.4 2.1 2.9 2.4 See Open 2.7 3-9 3-5 3.8 a S..8; Open g. 4.5 4.0 5.0 et aR Cheesecloth shade 3.0 3.2 2 4.0 hd By, Cheesecloth shade 1.9 4.7 2.5 3-7 2-3 he Open 4.3 at ei 4.8 3-4 eee Open Ce 4.2 am 5-3 3-5 and with the plants. The Physalis plant lost an inordinate amount in period 6, the brown cup lost what appears as too much in period 3, and the behavior of the Xanthium plant in the last three periods is unusual; otherwise the agreement in the different ordinates is about what should be expected. Attention may be called to the general ascent of the series of three maxima for two of the instru- ments, showing clearly the gradual increase of the sun’s intensity from 8:00 A.M. to 1:00 P.M. Also, with the thinner shade neither of the plants and neither of the dark instruments exhibit such a fall in rate of water loss as they do in the denser shade. We may now turn to the quantitative relations shown by these series of data. Since the use of two different shades really constitutes soles separate tests, we may consider the observations for the first six periods as test I, and those for the last six as test II, there being a common period of sunshine for the two tests. If now we calculate the ratios of the two sun periods, respectively, in each test, t© those of the shade period intervening, we shall obtain quantitative 1911] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 429 measures of the relations which we wish to study in detail. But It is obvious that the first half-hour in any condition fails to give as clear an expression of the response to that condition as does the second half-hour, there usually being a more or less marked Fic, 1 lag of effect behind cause; therefore we need give attention only to the second period in each condition. Thus a period of 30 minutes is allowed to elapse after each change of conditions before use is made of the data obtained. This is a common method for the 439° BOTANICAL GAZETTE [DECEMBER treatment of such changes in physics as well as physiology. The two second half-hour periods of sunshine will be termed the first and second sun exposures, the second half-hour of shade giving us the measure for the shade exposure. All of the sun-shade ratios are given in table II. Examples may make the procedure of their derivation more evident. The first ratio of test I for Physals is 3.0+1.7, or 1.76. The second ratio for the brown atmometer in test II is 4.12.5, or 1.64, etc. TABLE If SUN-SHADE RATIOS OF RATES OF WATER LOSS Physal. | Xanth. | Blk. atm. | Brn. atm. | Wht. atm. est E evecaha deg 1.76 35 2.05 1.62 1.17 (canvas) 2d sun exp.....} 3.00 1.88 1.90 1.72 4-49 est ist sunexp....} 2.68 | 1.22 1.60 1.35 1.35 (cheesecloth) / 2d sun exp..:..| 1.84 ae 1.64 1.43 1.52 If both plants were influenced alike and only by the direct heating of the sun’s rays, and if the instruments were affected by radiant energy just as were the plants, that is, per unit of surface exposed, then we should expect all these ratios to be equal. _ In so far as they are not equal, they signify a variation in the effect produced upon the two plants and upon the three instruments by the same alterations in light intensity. Thus, if any one of these instruments were used as a basis for light measurement, to predict the influence of light changes upon either of these plants, the instru- mental result must obviously be corrected. Since it is already clear that the two plants do not entirely agree in their sun-shade ratios, it will be necessary to find correction coefficients, not simply for each instrument, but for each instrument for each plant. From the sun-shade ratios of table II have been calculated the correction constants, by which the ratio of any instrument for any period is to be modified (multiplied) so as to equal the corresponding ratlo for either plant, and these coefficients are given in table IT. As an example of the method of derivation, the first coefficient of cor- rection for the black atmometer in reference to Physalis (test I) is tort] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 431 1.76+1.62, or 1.09. Each pair of coordinate coefficients for each test is averaged, also, in the table. TABLE III CORRECTION COEFFICIENTS Brown atmom. | Black atmom. | White atmom. Physal. Xanth. | Physal. | Xanth. | Physal. Xanth. Ist sun exp...|. 0:86 0.85 1.09 1.08 t.66 233 Test I | 2d sun exp....| 1.58 ©.99 r.74 1.09 1.50 1.46 Average..... 122 0.92 1.42 I.09 60° 7 3290 Ist sunexp...} 1.69 0.76 1.99 0.90 T.99 2.90 Test II | 2d sun exp....| 1.12 0.70 1.29 0.80 59% 0.75 Average ..... 1.40 | 0.73 1.64 | ©. 85 | 1. 0.83 The second series of observation (test III) was carried out from 10:00 A.M. to r:00 P.M., August 11. The shade here used was of two thicknesses of cheesecloth. Three plants were used, one of each of the forms above mentioned, but different specimens, and one of Martynia louisiana. Besides the three atmometers, all of our other instruments were operated in this series. We may neglect the losses for the first half-hour periods of each exposure, since they are not to be used in calculating the different ratios. The rates of loss, or in the case of non-evaporating instruments the averages of two readings taken at the beginning and end of the ~ Second half-hour of each exposure, are given in table IV, and the corresponding coefficients of correction in table V. There was almost no discrepancy shown between the first and second readings of the non-evaporating instruments; the conditions for the half-hour Were sensibly constant. In the case of the two photographic papers the ratios are of course inverted, since the light intensity must vary inversely as the time required to produce the given depth of color. A third series (test IV) was carried out on August 12, from 10:00 A.M. to 1:00 P.M. The plants were similar to those of test III, but were different individuals; the shade was of canvas, as in test 1, For this series only the final coefficients of correction and their averages need be given. They may be found in table VI. BOTANICAL GAZETTE [DECEMBER 432 TABLE IV LossES AND READINGS PER 30 MINUTES Tele te F Test III ae ee eee :3 SB) Elei gi el gig} | 3 hs br Bg pag Ei UTe Ele al Fl eee a ee eee Mee ere 1st sun expo: .-| 3-45| 3-98] 3.12| 2.9 | 3-7 | 2.2 | 3 34-5| 2-4 | 6.7 Double aeenabite SHAME ues occ 2,88] 3.48| 2.701; 2.6 | 2:6 | 2.2 | 1.71 95.01 5-5 | 3-9 ad sun exposure.....| 4.35] 4.05] 3.54] 3-3 | 4-5 | 2.7 | 2-95| 38.0] 2-15] 6-5 TABLE V COEFFICIENTS OF CORRECTION Test III Brown atmometer Black atmometer Physal. | Xanth. | Martyn. | Physal. | Xanth. | Martyn. Ist sun exposure ...| 1.07 1.02 1.04 0.85 0.80 0.82 2d sun exposure....| 1.19 0.91 1.03 0.87 0.67 0.76 Avelage. 3. oss 1.13 0.97 1.04 0. 86 0.74 0.79 - White atmometer Integrator Physal. Xanth. Martyn. Physal. Xanth Martyn. Ist sun exposure...) 1.20 1.14 1.16 0.69 0.65 0.66 ad sun exposure. . 1.23 0.94 1.07 0.87 0.67 0.76 ee Aves... 1.22 1.04 1.12 0.78 0.66 ahh oe a s “Solio” paper Wynne paper Physal. Xanth Martyn Physal. Xanth Martyn Ist sun exposure . . °. 0.41 0.42 0.52 0.50 ae 2d sun exposure....| 0.60 0.46 0.52 0.59 0.45 ei Average... 6... 0.52 0.44 0.47 0.56 0.48 0.5! ae Black thermometer Physal. Xanth. Martyn. Ist sun exposure ...| 0.54 0.51 0.52 2d sun exposure...| 0.70 flies iy Average ee Gee Soa 0.62 0.52 0.56 eee eee aan 1911] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 433 TABLE VI COEFFICIENTS OF CORRECTION Test IV Brown atmometer Black atmometer Physal. Xanth. Martyn. Physal. Xanth. Martyn. Ist sun exposure ... 1.38 T.09 0.99 1.38 1.09 0.99 2d sun exposure.... xuRs 1.26 0.07 1.46 1.21 0.93 etieRe ces. 1.46 | 1.18 0.98 | I.42 Se 0.96 White atmometer | Integrator Physal. Xanth. | Martyn. | Physal. | Xanth. | Martyn. Ist sun exposure ... ae 1.58 1.43 0.43 0.34 O.47 2d sun exposure.... 4,23. {+2 7208 120 0.69 0.57 0.44 Pomtage 2k a. k. 1.61 1.63 | 1.36 0.56 | 0.46 | 0.38 “Solio” paper : Wynne paper Physal. | Xanth. | Martyn. | Physal. | Xenth. | Martyn. Ist sun exposure ...|- 0.21 0.16 O.t5 0.43 | 0.34 0.31 2d sun exposure....| 0.25 0.21 0.16 0.51 0.43 0.33 nbhee: 2 Scan 0.23 0.18 0.15 0.47 | 0.30 | 0.32 Black thermometer Physal. Xanth. Martyn. Ist sun exposure...| 0.40 0.31 wild 2d sun exposure ...| 0.49 0.40 @.3f Bverase 2 0.45 0. 36 0.39 Finally, in table VII are brought together all the average coef- ficients from the preceding tables, together with their averages, for each plant for the whole investigation. This second average gives Us a Coefficient that may be taken to represent each instrument with reference to each plant. The average of the three different coefficients thus obtained for each instrument is given in the last column of the table. The latter average may perhaps represent the correction to be applied to each instrument for plants in general. Of course the latter statement is a pure assumption, based on the 434 BOTANICAL GAZETTE [DECEMBER gratuitous supposition that plants in general may be found to average up, in their sensitiveness to light intensity, as did the three which happened to be used in these tests. TABLE VII | COEFFICIENTS OF CORRECTION AVERAGE INSTRUMENT Plant Test I | Test II | Test III | Test IV | For plant} For instr. Physal. =... Tiss) oT. 40.) res TAG | 2230 Brown atm..... mateo. 0.92 0:73 0.97 T.18-) 0:65 1.09 Martyn. <2... ee Sar 1.04: f° 6:98 4 “T0Gr 7 Physah 2. E41 r6e|. 6.864: 3.471. 83 Black atm..... 2 Ct ee 1.09 | 0.85 | 0.74| 1.15 | 0.96 |} 1.06 Martyn..... Hee abs 0.79 | 0.96| 0.88 : PUyHe 2 2. I.92| 1.60 “a.e2 | 1.61 | 1.59 White atm..... pt 2 RO aes ¥.48 | 6.83 | 1.04 | 1.63 | 1.99 (pee Martyn..... wees ven ¥.12 40:) 2224 Physal. ..... ee eee 0.78 | 0.56| 0.67 Integr: 2... Maths css: ave bo. 41 3.06 1-046 p 0.567 ee Martyn..... Oo. 72 | 0.98 | 6:58 Physal...... 0.52 23 |:.0.38 **Solio”’ paper. . AA, yc, ) 0.18 | 0.31 | (9-33 Martyn..... 0.47 15 | :O:gt Physabo os: ae PIS; 0:56 | 0.47 | 8.52 Wynne paper .. PANU ys ee Niet 0.48 | 0.39 | 0.44 0.46 Martyn..... eS ciga [om §E 1. 0.32) Oras Physal.. 3.5: 62 | 0.45 | 9.54 Black therm... . Rann See 0.52 | 0.36} °o. 0.47 Martyn..... 156 |: 0.30 | 0-43 Conclusions In the last section have been brought forward the results of an experimental attempt to determine what sort of corrections must be applied to the data furnished by the seven instruments tested, in order that we may obtain from these data the sun-shade ratios of the transpiration rates as actually exhibited by the different plants. Four tests, each furnishing two sun-shade ratios for each . plant, have been carried out. In all, we have eight tests for Physalis and the same number for Xanthium, but only four for Martynta. It is safe to assume that the full sunshine for the three days of this inquiry was approximately the same; all tests continued through . tgt1] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 435 about the same part of each day. It is quite obvious that in other regions the results might have been different, but I am convinced that the present data would agree fairly well with those for the hottest summer days in most parts of the United States. It is to be remembered, however, that the work was done in the arid region, albeit in the moist season, and that humidity has not yet been investigated with reference to its quantitative effect on plant transpiration. In the absence of a better method for describing weather conditions, it may be stated that the temperature varied within the limits 30-35° C., and the sky was not without haze, though clouds were rare. We have considered nothing weaker than strong diffuse light, that obtained under a screen of tent canvas. The plant stomata were probably always in the day con- dition throughout these experiments, and incipient wilting, if it occurred, was probably not generally a controlling factor in the transpiration rates. Several different shade intensities were included in the tests, but an inspection of the tables will convince one that the fluctua- tions in the correction coefficients do not appear to be related to any particular shade. In the following derivation of conclusions all tests will be considered as tentatively equivalent, and no attempt to weight the averages will be made. The coefficients of correction will be treated as the main criterion for judging of the relative degrees of sensitiveness of the plants and instruments toward variations in light intensity. 1. Considering all coefficients (tables III, V, and VI, not the averages) with values between 0o.go and 1.10, inclusive, as equal to unity, we see that all of those greater than unity have reference to the porous cup atmometers. The other instruments always recorded greater differences between the two light intensities than did any of the plants. To study the distribution of the different forms of coefficient more in detail we may proceed to classify them in each of these two groups of instruments. The frequencies of occurrence of coefficients less than, equal to, and greater than unity, for the three atmometers and the three plants, are presented in table VII. For example, there are six coefficients greater than one occurring for the brown atmometer and Physalis, only one for 436 BOTANICAL GAZETTE ‘ [DECEMBER Xanthium, and none for Martynia. The last column of the table gives the total number of comparisons made. TABLE VIII Instrument Plant Cras C=r G4 Total Pita ee oa I I 6 8 Brown atm....4 | Xanth.......... 3 4 I 8 Mattyn S02 eu: ° 4 ° + Physab eh: 2 I 5 8 waeek Sn. 4 | Aamo... 3 4 I 8 MANO a 2 2 ° 4 Cl Piel. 2.0 ss ° ° 8 8 White atm... 1) Manth..-... sic, I 2 5 8 iv, ) I 3 4 2. From table VIII we derive the generalization that for all cups, under all test conditions, Physalis shows the most frequent occur- rence of coefficients greater than unity. Martynia shows the least frequent occurrence of these. Physalis, therefore, is usually more sensitive to light changes than the cups; the other two plants are generally equally sensitive or less so. 3. For the white cup, for all plants, and under all test conditions, the great majority (16 out of 20) of the coefficients are greater than unity. This cup is generally not as sensitive to light varia- tions as are the plants. 4. The brown and black atmometers agree in giving mainly coefficients for Physalis which are greater than unity, while for the other plants they are equal to or less than unity; see 2. : Turning now to an analysis of the coefficients of the other 1n- struments, we may treat them as we have the atmometers, only classifying them as less than, equal to, or greater than 0. 50 instead of 1.00. We may consider as equal to 0.50 all coefficients from 0.40 to 0.60, inclusive. Table IX presents the classification on this basis. 5. It appears from this array of figures that the integrator gives predominance to coefficients greater than 0.50, while the other instruments give them equal to or less than 0. 50: 6. “Solio” paper shows the strongest tendency to give coefli- tott] LIVINGSTON—LIGHT INTENSITY AND TRANSPIRATION 437 cients less than 0. 50, but half of those derived from this instrument are equal to 0.50. TABLE IX Instrument Plant | C<0.50 C=o0.50 C> 0.50 Total PRYSOL er: ° I 3 4 Integrator ....... POT ee ee I I 2 4 Martyn... I I 2 4 os, Physeloo se 4 2 2 re) 4 Solio” paper....}]| Xanth....... 2 2 fe) 4 Martyn, 2.2 2 2 ° 4 Phivselo 2.3 4 fo) 4 Wynne paper ....}| Xanth....... I 3 ° 4 Martyn: : 2... 2 2 ° 4 : Physats 3), ° 4 I 4 Black therm ..... anh. SF... I 3 ° 4 Martyn. cs. 2 2 ° 4 7. From the Hicks integrator and the black bulb thermometer evidence is again presented that Physalis is more sensitive to light changes than either of the other plants, and it is suggested that Martynia may be somewhat less sensitive than Xanthium. From the grand averages of table VII we may derive some ap- proximate notion of the values to be taken, in general, as correction constants in the operation of these instruments. It must be borne in mind that the data are inadequate and the conclusions tentative in the extreme. 8. Physalis appears to be about a third more sensitive than the two dark cups, which agree well together. Xanthium and Martynia appear nearly to equal these cups in sensitiveness. The average correction factor for all three plants is 1.075. : 9. Physalis appears to be about 60 per cent, the other two plants only about 25 per cent, more sensitive than the white cup. The average correction factor for the white cup is 1.36. to. All three plants are somewhat more than half as sensitive as the Hicks solar radio-integrator, the average correction for which iS 0.59; see 5 above. 11. The Wynne actinometer and the black thermometer agree well in showing a sensitiveness about double that of the plants, 438 BOTANICAL GAZETTE [DECEMBER more than double for Physalis and less than double for the onic, = 12. The Clements instrument, with “‘solio” paper, seems to be generally about three times as sensitive as are these plants, some- what more than this for Xanthium and Martynia, somewhat less for Physalis. From these averages it appears more sensitive than by the method of frequencies; see 6 above On the whole, we may conclude that the black and brown atmometers and the Hicks integrator have shown themselves to be valuable instruments for estimating the solar intensity, so far as transpiration is concerned. They should be suitable for the com- parison of light intensities in different habitats, etc., and they are especially to be recommended on account of their power of auto- matic integration, and also on account of the fact that they all give their results in terms of vaporization of a liquid, thus resembling the plant in its transpiration activity. The black bulb thermometer _ recommends itself as the best of the non-integrating devices. The photographic papers are not to be highly recommended as used in this inquiry, mainly on account of their failure to record effects of other than restricted wave-lengths. They may be modified so as to be more available, and may, possibly in their present form, be even more valuable than the other instruments here tested, when the effects of light variations on photosynthesis rather than trans- piration are to be determined. THE Jouns Hopkins UNIVERSITY BaLtmore, Mp. THE EMBRYO SAC OF EPIPACTIS: WILtiam H. Brown AND LESTER W. SHARP (WITH PLATE x) The present study is based upon material of Epipactis pubescens (Willd.) A. A. Eaton, collected at Cold Spring Harbor, N.Y., in August 1909. The archesporium is distinguishable very early as a single hypodermal cell which terminates an axial row surrounded by a single epidermal layer. As growth proceeds, the young ovule becomes strongly anatropous and develops two integuments, the outer one being continuous with the slender stalk. Since the nor- mal heterotypic prophases always occur in the nucleus of the . archesporial cell preparatory to its first division, it is to be regarded as the megaspore mother cell, no parietals being formed. The subsequent course of development to the complete embryo sac is not identical in all ovules, the same end being reached by a variety of methods. The behavior in what probably represent the Majority of cases is as follows. After becoming considerably en- larged, the megaspore mother cell undergoes its first division (fig. 1). Since the spindle lies near the micropylar end of the mother cell, the resulting daughter cells are very unequal in size (fig. 2). The larger, chalazal cell again divides unequally, forming two mega- Spores, while in only a single case was the micropylar daughter cell observed in process of division (figs. 3 and 4). The innermost megaspore enlarges and gives rise to the embryo sac, while the other cells of the row soon degenerate. The nucleus of the functioning megaspore divides to two (fig. 5), and very soon small vacuoles appear in the cytoplasm, mostly in the region between the two nuclei. Meanwhile the sac grows considerably, but continues to have the general shape of the mega- spore mother cell. As growth proceeds, the increase in volume of the cytoplasm fails to keep pace with that of the sac cavity, so that Contribution from the Botanical Laboratory of the Johns Hopkins University ro Po a t of th bry written by Mr. SHa , oe. oy 7 and the discussion by Mr. BRowNn. 430] [Botanical Gazette, vol. 52 440 BOTANICAL GAZETTE [DECEMBER the small vacuoles in the central region coalesce to form a large central one (fig. 6), the cytoplasm becoming spread out as a parietal layer which is thickest at the ends of the sac where the radius of curvature is small. The two nuclei lie in these two regions. These nuclei soon divide simultaneously, giving rise to the four-nucleate sac (fig. 7). In this division and in the preceding one no traces of cell plates could be distinguished on the spindle fibers. After considerable enlargement of the embryo sac, the third division occurs, the two spindles formed in each end varying in position. Usually they lie approximately at right angles to each other; in such cases they may be equidistant from the end of the sac (fig. 8), or one may lie at a little distance from the other along the lateral wall. Cell plates appear on the fibers of all four spindles, so that the resulting eight nuclei are separated in the usual manner. In the micropylar end the transverse spindle gives rise to the two syner- gids, while the longitudinal one forms the egg and polar nucleus. In the chalazal end three antipodal cells and a polar nucleus are formed in an exactly similar manner (fig. 9). The egg and synergids increase in size, and the two polar nuclei approach each other and fuse (fig. 10). Exceptionally the two spindles in the chalazal end of the sac, instead of lying at right angles, come to lie more or less parallel to each other and usually to the longitudinal axis of the sac (fig. 11). As division proceeds they may become coalesced, forming one large spindle instead of two ordinary ones (figs. 12-14). The con- clusion that such is the explanation of the large spindle shown in fig. 12 is supported by the fact that the plate of chromosomes could be seen by focusing to be made up of two groups of approximately equal size, and that altogether their number was plainly larger than that in either of the micropylar spindles. The same was true of the corresponding spindle of fig. 13. The division of this double spindle may keep pace with that of the micropylar ones (fig. 12); or it may be delayed as shown by figs. 13 and 14. In fig. 14 the wall on the fibers of the chalazal spindle is only slightly younset than those of the micropylar ones, showing but a slight delay. In fig. 13 the delay has been greater, the chromosomes of the chala- zal spindle having very recently separated, while in the micro- tgrt] BROWN & SHARP—EPIPACTIS AAI pylar end distinct walls and nuclear membranes are present. The wall which appears on the fibers of the double spindle cuts off one nucleus in the base of the sac, and leaves one free in the cyto- plasm (fig. 15). In these cases the latter nucleus apparently fuses with the polar nucleus from the typical micropylar group, while the one cut off by the wall later disorganizes (fig. 16). That sucha six-nucleate condition offers no hindrance to fertilization is evi- denced by the sac represented in fig. 16, in which a two-celled embryo is present. In fig. 11 the chalazal spindles have taken up a nearly parallel position, but at too late a stage to coalesce, since membranes are already present about the four nuclei. It is probable that in this - case a continuous wall would be formed across the base of the sac, cutting off two nuclei and leaving two free in the cytoplasm, but no sac was observed in which such an end had been reached. These Phenomena appear in most cases to be in some way associated with a narrow configuration of the chalazal end of the sac at this time, and a consequent diminution in the amount of cytoplasm present there. In other cases the fate of the megaspore mother cell is quite different from that described in the foregoing account. After enlarging somewhat the nucleus divides, the spindle lying at about the center of the cell, so that the thin wall formed upon the fibers Separates the mother cell into two nearly equal daughter cells (fig. 17). The wall, however, soon disappears, leaving the two nuclei in a single cell cavity which is to form the embryo sac. Between the nuclei vacuolation occurs, so that the center of the Sac comes to be occupied by a single large vacuole, the two nuclei taking up positions at opposite ends of the sac, where the greater part of the cytoplasm lies (fig. 18). Aside from the conspicuously larger size of the sac and its nuclei, this stage is closely similar to the corresponding one of a sac derived from a single megaspore. It is important to note that here the epidermal layer of the nucellus could be seen to be everywhere in contact with the sac, degenerat- ing cells being clearly absent (cf. figs. 6 and 18). The two nuclei again divide, and delicate walls appear on the spindle fibers between each pair of resulting nuclei. Later both 442 BOTANICAL GAZETTE [DECEMBER walls may become quite distinct (fig. 19), though they vary some- what in position owing to the various planes in which the spindles may lie. In the figure shown they are transverse to the longitudinal axis of the sac, so that the four nuclei have a linear arrangement. Usually, though not always, these walls disappear very soon. In the event of their complete disappearance, there results a four- nucleate sac like that represented in fig. 20, which is essentially the same as one derived from a single megaspore, but is conspicuously larger. That the four nuclei here shown have resulted from fewer divisions from the nucleus of the archesporial cell than have those in four-nucleate sacs derived from one megaspore seems to be indicated by their relatively larger size (cf. figs. 7 and 20). A similar condition was pointed out in connection with the two- nucleate stage (cf. figs. 6 and 18). t a stage as late as the four-nucleate sac it becomes very difficult to determine whether degenerating cells at the micro- pylar end of the sac are present or not, so that it is unsafe to depend . too strongly upon them as a criterion, but after the examination of a large number of cases the present writers hold the view that the four nuclei, which, on account of their origin and the appear- ance of walls at the mitoses which give rise to them, are megaspore nuclei, and that these by one further division give rise to an eight- nucleate sac entirely similar to one derived from a single megaspore- Important evidence in this connection is afforded by the wall formed between the two chalazal (megaspore) nuclei, which often shows a tendency to persist. In fig. 21 it is still visible as a remnant during the division to form the eight nuclei of the sac, the four spindles in this case showing an unusual irregularity in distribution. Since one of the micropylar spindles was in an adjacent section, it was not possible to demonstrate the presence of a wall in that end. In other cases the wall persists for a longer time, giving rise to the condition shown in fig. 22. Here it is observed separating the two undivided chalazal nuclei, while at the micropylar end the next division has taken place, cell plates being evident on the spindle fibers. A somewhat later stage is represented in fig. 23- The persistence of the wall seems to result in a delay of the nuclear divisions (fig. 21), or in their suppression, as shown by figs. 22 and 23- 1911] BROWN & SHARP—EPIPACTIS 443 The fact that in these cases the wall between the two chalazal nuclei is decidedly thicker than those between the micropylar nuclei would seem to indicate that it had been formed at the time of megaspore formation rather than later by a double spindle as described above, for in the latter case the division of the double spindle lags behind that of the micropylar ones. It thus appears that a six-nucleate sac of this type may originate by either of two methods. Should the wall formed at the first division of the megaspore mother cell persist until after the second division, we should have a development similar to that of Smilacina (MCALLISTER 9g), in which the walls separating the four megaspores break down, leav- ing in a single large cell the four nuclei, which then divide once to form an eight-nucleate sac. A number of two-nucleate sacs were observed with apparently but one degenerating cell present at the micropylar end. Further evidence on this point was not obtained, but these may represent cases in which the embryo sac is being derived from a daughter cell, or, in the light of the above, from two megaspores. The development of embryo sacs from two or from four mega- spores in a plant, which also forms them from one megaspore in the usual manner, may be regarded as steps in the reduction of the number of nuclear divisions occurring between the archesporial cell and the formation of the egg. When four megaspores take part in the formation of an eight-nucleate sac, the egg is removed from the archesporial cell by three divisions, as is also the case in Cypri- pedium (Pace 11), in which the egg nucleus is one of four formed in one daughter cell. Should one more division in any way be elimi- nated, the egg nucleus then being one of the four products of the reducing divisions, the gametophytic generation would be repre- sented by a single nucleus, and the condition would be exactly comparable to that of the animal egg. The further fate of the embryo sac, whether derived from one, two, or four megaspores, is apparently the same. The pollen tube makes its way through the micropyle into the sac, disorgan- izing one of the synergids, and liberates two male nuclei, one of which fuses with that of the egg, and the other with the product 444 BOTANICAL GAZETTE [DECEMBER of the fusion of the polar nuclei (fig. 24). The endosperm nucleus which results from this fusion enlarges but does not divide, and soon degenerates along with the antipodals (fig. 25). The first division of the fertilized egg is transverse (fig. 16). The second division is in the micropylar cell and is also transverse, while the third (fig. 25) separates the.chalazal cell into two by a longitudinal wall. These two divisions frequently occur simul- taneously. Intermediate stages in the development of the embryo were not observed, but in the mature seed, which is of the usual orchidaceous type, it consists of a small, oval, undifferentiated mass of cells with no suspensor. Discussion Owing to the definite course of development in many of the animal eggs, the zoologists have been able to study some of the factors concerned. They have found in some cases that structures develop independently. In others some organs do not appear if certain parts are wanting, while in still other cases, as the lens of the amphibian eye (SPEMANN 14), structures, which at one time probably required the presence of another organ for their develop- ment, have during the course of evolution come to develop inde- pendently. The factors concerned in the development of plants have been studied much less than in the case of animals. This is perhaps due to the fact that most of the plants which show determinate development are inclosed, during their early stages, in the tissues of the parent. It is well known, however, that the form of a plant may be greatly affected by external conditions. A striking case is that of Stigeoclonium, in which, according to LIVINGSTON (8), the cells develop into a palmella stage or elongated filaments according to the osmotic strength of the nutrient solution. HARPER (6) in studying H ydrodictyon concluded that the shape of the net was due to the shape of the parent cell, while the axis of elongation of the individual cells was connected with the pressure exerted by neighboring cells upon each other. In Epipactis it is not evident why the nucleus of a megaspore should in some cases develop into the nuclei of a whole embryo sac, tort] BROWN & SHARP—EPIPACTIS 445 and in others into those of only a portion of one. This may be due, however, to some condition such as nutrition, which is external to the megaspores, and is probably not due to potentialities inherent in the various megaspore nuclei, for it would seem that the nucleus of each megaspore, if placed under proper conditions, would have the potentialities for producing the nuclei of a complete sac. This conclusion is supported by the large number of cases in which the development of more than one megaspore in a tetrad has been described (Coutrer and CHAMBERLAIN 4). Differences in the potentialities of the megaspore nuclei, moreover, could not explain the differences in development, for the course can be predicted at metaphase of the reducing division. Different potentialities if they existed would, therefore, have to be in the nuclei of the differ- €nt megaspore mother cells; but according to present theories of heredity all mother-cell nuclei possess equal potentialities. The most reasonable conclusion would seem to be that the different courses of development are due to conditions external to the nuclei, and that the fate of a nucleus will depend on its position. It would seem probable, moreover, that the conditions which determine the fate of a nucleus, when four megaspores combine to form a normal Sac, must be the same as those which determine the fate of the nuclei of a sac formed from a single megaspore. The formation of a normal sac from four megaspores in Lilium (CouLTER and CHAM- BERLAIN 4), Smilacina (MCALLISTER 9), and also in the large number of cases in which a row of megaspores is not formed, as well as from the aposporous outgrowths into the cavity of the degenerated embryo sac of Hieracium (ROSENBERG 13), and in Alchemilla (MurBecxk 10) from the megaspore mother cell without a reduction in the number of chromosomes, would seem to in- dicate that the formation of a sac is not due to the nature of the cell from which it is produced, but that a normal sac will be formed from any cell subjected to the conditions under which a megaspore would produce one. The determining conditions in all of these cases, or at least most of them, are probably the same as in Epi- pactis, and since these conditions appear to be widely distributed among the angiosperms, they may have been the original cause of the evolution of the eight-nucleate sac. This could be true even 446 BOTANICAL GAZETTE [DECEMBER if it should be shown that some normal sacs are formed without the original determining condition, for cases apparently quite similar to this are known among animals. A striking example is the lens of the amphibian eye (SPEMANN 14), which in some species requires the presence of the optic cup for its development, while in others it develops even if the optic cup is removed. From the foregoing discussion it does not follow that the nuclei play a passive part in development; for the external conditions which influence them may in turn be due to the nuclei from which these have been derived, i.e., the vegetative nuclei of the plant; and if a nucleus were other than it is, it probably could not react to external conditions to produce the structures which it does. Any analysis of the conditions determining the course of devel- opment of the embryo sac must at present be incomplete and largely tentative, but a comparison of the conditions under which various types of sacs are formed may be worth while, as it is likely to sug- gest new ways of looking at their origin and development. The first point to be considered is the production of polarity. Before the megaspore mother cell divides, it has the general shape of the mature sac, and an enlargement of the whole nucellus without further change would preserve this shape. The formation of the megaspores in rows in most angiosperms, and the elongation of the nucellar cells in a direction parallel to this row would indicate that the elongated shape of the functional megaspore and the sac is connected with the direction of greatest pressure in the nucellus. When the nucleus of the mother cell divides, the daughter nuclei, as is usually the case, tend to be evenly distributed in the cyto- plasm. After vacuolization, a continuation of this same tendency would carry the nuclei to the two ends of the sac, where surface tension would cause the accumulation of the cytoplasm. The conclusion that this is the explanation of polarity is supported by the development of the sixteen-nucleate sacs. In Peperomia sintenesit (BROWN 1), where the sac would seem to be derived from four megaspores, the mother cell and embryo sac are both rounded, and there is no polarity. The same thing is true in the Penaeaceae, where Miss STEPHENS (15) believes that the embryo sac is derive tgrr] BROWN & SHARP—EPIPACTIS : 447 from four megaspores. In Peperomia hispidula (JOHNSON '7) and in Gunnera (ERNST 5) the embryo sac is rounded at the four-nucleate stage and there is no polarity, but as development proceeds the sac elongates and polarity is produced. In Strelitzia (BROWN 3) there are four megaspores, each of which may germinate, but the three micropylar ones degenerate and the sac is always formed from the chalazal one. The three micropylar megaspores are not elon- gated and their nuclei do not show a polar arrangement. At the second division of the embryo sac of Epipactis the spindles are arranged so that the daughter nuclei are again evenly distributed in the cytoplasm. At the third division the spindles in both ends are usually arranged approximately at right angles to each other. This is of course usually the case in the ends of embryo sacs and in other rounded masses of cytoplasm, and would seem to be the way in which the spindles and resulting nuclei would be most evenly dis- tributed. In Epipactis, however, the chalazal end is sometimes narrow, and in this case the two spindles lie side by side. The simultaneous division of the nuclei and the production of an equal number in each end is probably connected with the similar condi- tions in the two ends. The number of nuclei is very likely due to some kern-plasma relation. In later stages the similarity of the two ends is destroyed and the nuclei take on quite different appear- ances. In Epipactis there is sometimes less cytoplasm in the chala- zal than in the micropylar end, and this is connected with a delay in the divisions in the chalazal end. STRASBURGER (16) has pointed out that the walls produced at the last division in a normal eight-nucleate sac are formed on the fibers connecting the nuclei, and that since one nucleus at each end is nearer the center than the other three, no wall is formed around it, thus leaving it free in the cytoplasm. He ascribes the fusion of these two polar nuclei to the fact that they have ceased develop- ing and are in the same cell cavity. Evidence strengthening this Position has been constantly accumulating and, as previously Pointed out (BRown 1), is quite striking in the case of the sixteen- nucleate sacs, where all of thesnuclei not cut off by walls fuse to form the endosperm nucleus. In Epipactis the polar nuclei are 448 BOTANICAL GAZETTE [DECEMBER produced in a variety of ways, but always fuse to form the endo- sperm nucleus, although this does not develop further. It would seem that even the final fate of the nuclei may depend largely on interacting conditions, for the synergids in those cases in which a sac is formed from four megaspores, as in the normal cases, are formed from the pair of nuclei arising from the transverse spindle. That the nuclei at this stage are equipotential is indicated by the occasional fertilization of one of the synergids (COULTER and CHAMBERLAIN 4). The structure of eggs, synergids, antipodals, etc., probably depends largely on the nature of the protoplasm of which they are constituted, and is of course widely different in different plants; but the part which any particular nucleus in Epipactis, and probably in other angiosperms, is to produce, as well as the general arrangement of the sac, apparently depends on the relation of the nucleus to other parts rather than upon any quality inherent in it. According to the above interpretation, the embryo sac in its early stages may be regarded as a system, all parts of which are equipotential, the fate of the different parts being connected with conditions external to them. The course of development in certain animal eggs is connected very largely with a stratification of the materials composing them, but in the early stages of many of these eggs a cell may develop into a whole embryo or some fraction of one, depending on whether or not it is separated from others. This dependence of the course of development of a cell on its rela- tion to conditions external to it, therefore, seems to be common to both plants and animals. The foregoing analysis, in so far as it goes, may be taken as indicating that the parts concerned act according to mechanical principles and do not need a vitalistic force to explain their behavior. This would seem to be true of any analysis which shows an orderly relation between an antecedent and consequent event, because for a thing to be mechanistic (this term being used in its widest sense) means simply that when the events are reduced to their simplest terms they take place in an orderly and predictable sequence. An analysis may bring to light new elemental laws of a different 1911] BROWN & SHARP—EPIPACTIS 449 kind from any that we know at present, but in so far as they are laws of an orderly sequence, they will be as good a mechanical explanation as any other law, for a law can only state the sequence, and it is outside the realm of science to explain why one event fol- lows another. Any vitalistic explanation must therefore be either outside ‘and supplementary to science or contrary to the funda- mental postulate of all science, namely, that the same antecedent conditions are always followed by the same consequent ones. If we compare the development of the angiosperm embryo sac with that of the gymnosperms, we find in the early stages a strik- ing similarity between those of the gymnosperms and the sixteen- nucleate sacs of the angiosperms. In both cases the nuclei are fairly numerous, evenly distributed in the cytoplasm, and do not Show a polar arrangement. This similarity, however, is probably derived and not primitive in the case of the sixteen-nucleate sacs, for some of these, at least, are derived from four megaspores. There would appear to be in the gymnosperm embryo sac nothing similar to the striking polarity shown by those of most angiosperms, but that the same factors are at work is perhaps indicated by the elongated shape of the embryo sacs of many of the gymnosperms, as well as the tendency toward a reduction in the number of nuclei, and the presence of a large central vacuole. Likewise the presence in the early stages of the gymnosperm embryo sac of free nuclei Surrounded by a cellular region may foreshadow the free polar nuclei of the angiosperms. Porsc# (12), in an excellent discussion of the phylogeny of the angiosperm embryo sac, has attempted to point out a similarity between the archegonia of the gymno- sperms and the two polar groups in the angiosperms. When we remember, however, that in those gymnosperms which have archegonia they are initiated in a cellular phase and the polar groups of the angiosperms in a non-cellular one, it would seem that any similarity between the development, final structure, or factors concerned must be rather superficial. It would probably be better to regard the structure of the angiosperm embryo sac as the result _ot new physiological conditions which have arisen in connection with the reduction of its size and the number of its nuclei. 450 BOTANICAL GAZETTE [DECEMBER Summary 1. The archesporium of Epipactis consists of a single hypodermal cell, which, without formation of parietals, functions as the mega- spore mother cell. 2. In most cases the megaspore mother cell divides to two unequal daughter cells, the chalazal one again dividing to form two megaspores. The innermost megaspore then gives rise to the embryo sac. 3. In other cases four megaspores take part in the formation of the sac, the walls appearing at the first two divisions of the mega- spore mother cell being evanescent. At least one of these walls often shows a tendency to persist, which results in a six-nucleate type of sac. The same appearance may also result from irregulari- ties in the orientation of spindles. 4. There is some evidence that the embryo sac may at times be derived from two megaspores. 5. che normal mature embryo sac contains an egg, two syner- gids, three evanescent antipodal cells, and two polar nuclei which fuse. 6. The usual type of ‘double fertilization” occurs. 7. The fertilized egg gives rise to an embryo, which, at least in the seed, has no suspensor. 8. The endosperm nucleus, formed by the fusion of one male nucleus with the two polar nuclei, disorganizes without dividing. 9. The variety of methods by which the embryo sac of Epipactis is formed may be regarded as a series representing a reduction in the number of nuclear divisions occurring between the archesporial cell and the formation of the egg. 1o. The fate of the nuclei in the different courses of develop- ment is probably due to some conditions external to them rather than to any inherent potentialities. A normal sac would probably be produced by any cell subjected to the conditions under which a mother cell would produce one. 11. The sac in its early stages appears to be an equipotential system, polarity being connected with its shape, and the part that the nuclei are to play with their position. 12. The polar groups probably do not represent archegonia, 1911] BROWN & SHARP—EPIPACTIS - 451 but the general structure of the angiosperm embryo sac may be indicated by some features in those of the gymnosperms. The writers wish to express their thanks to Professor C. B. Davenport, director of the biological Laboratory of the Brooklyn Institute of Arts and Sciences, for courtesies shown them during their stay at Cold Spring Harbor; and to Professor D. S. JouNsoN for helpful suggestions and criticisms during the progress of the work. LITERATURE CITED 1. Brown, W. H., The nature of the embryo sac of Peperomia. Bor. Gaz. 46: 445-460. pls. 31-33. , The embryo sac of Habenaria. Bor. Gaz, 48:141-250. figs. I2. 1909. 3-——, The embryo sac of Strelitzia. 4- COULTER and CHAMBERLAIN, Morphology of angiosperms. 1903. p. 80. 5- Ernst, A., Zur Phylogenie des teens der —— Ber. Dedisch. Bot. Gesells. 26: 419-437. 8. 6. Harper, R. A., The organization of setith coenobic plants. Bull. Univ. Wisconsin, Science Series 3: 279-334. 1908. 7- Jounson, D. S., A new he of embryo sac in Peperomia. Johns Hopkins Univ. Cir. 195:19-21. 190 8. Livincston, B. E., Chemical stimulation of a green alga. Bull. Torr. Bot. Club 32:1-34. 1905. 9. McALuister, F., Se sapere of the embryo sac of Smilacina stellata. OT. GAZ. 48:2 ats. OF. .75, to. MurBEcK, S., Pationecuseche Embryobildng in der Gattung Alche- milla. RES Univ. Arsskrift 367: 46. 1 tr. Pace, Luta, Fertilization in Cini Bor. Gaz. 44:353-374. pls. 24-27, 1908. 12. Porscu, Orro, Versuch einer phylogenetischen Erklarung des Embryo- sackes und der doppelten Befruchtung der Angiospermen. 1 13. ROSENBERG, O., Ueber die ee in der Gattung Hieracium, Ber. Deutsch. Bot. Gesells. 24: 157-161. 14. SPEMANN, H., Ueber Linzenbildung nach ‘cet Entfernung der primidren Linsenbiidunaseetiead Zool. Anz. 28: 419-432. figs. 9. 1905. 15. STEPHENS, E. L., The embryo sac and embryo of certain Penaeaceae. Ann. Botany 23: ene: pls. 25, 26. 1909. 16. STRASBURGER, E., Die Samenlage von Drimys Winteri und die Endosperm- bildung bei Ansiospecnen. Flora 95: 215-231. 1905. 2. 452 ‘* BOTANICAL GAZETTE [DECEMBER EXPLANATION OF PLATE X All figures were drawn with the aid of an Abbé camera lucida, and show a magnification of 900 diameters. The following abbreviations are used: a, antipodals; d, daughter cell of megaspore mother cell; e, endosperm nucleus; m, megaspore; pt, pollen tube; s, synergid; co’, male deceu Fic. 1.—First division in the megaspore mother cell. Fic. 2.—Daughter cells resulting from division of megaspore mother cell. Fic. 3.—Two megaspores formed by the division of the chalazal daughter cell, and the undivided micropylar daughter cell. Fic. 4.—Micropylar daughter cell dividing; the only case observed. Fic. 5.—Young two-nucleate sac; spindle fibers still present; no separating wall; abortive megaspore and daughter cell represented by two deeply stain- ing masses. Fic. 6.—Two-nucleate sac after formation of central vacuole. Fic. 7.—Four-nucleate sac. Fic. 8.—Division to form eight nuclei. Fic. 9.—Eight-nucleate sac. Fic. 10.—Fusion of polar nuclei. Fic. 11.—Division to form eight nuclei; the two chalazal spindles show a tendency to become parallel to each other. : Fig. 12.—Metaphase of a similar division; the two chalazal spindles have mete to form a single large spindle. Fic. 13.—Later stage; the division es the coalesced chalazal spindles lagging behind ek of the micropylar ones. 1G. 14.—Telophase of a similar division; wall appearing on the fibers of the spindle formed by coalescence. 15.—Wall complete; the nucleus cut off in the base of the sac beginning to disorganize; its sister nucleus free in the cytoplasm with the polar nucleus of the micropylar group. Fic. 16.—Sac containing bwo-aled proembryo, endosperm nucleus, dis- organized cell in base, and pollen tu Fic. 17.—Nearly equal division of megaspore mother cell; wall formed on the spindle fibers. Fic. 18.—Later stage; the wall has disappeared and a central vacuole has formed. Fic. 19.—Four megaspore nuclei with evanescent walls. Fic. 20.—Four megaspore nuclei; the walls have disappeared. Fic. 21.—Four megaspore nuclei dividing to form the eight nuclei of the sac; megaspore wall still evident in chalazal end. Fic. 22.—Sac in which the chalazal megaspore wall has persisted. Fic. 23.—Later stage; walls in micropylar end complete. Fic. 24.—Double fertilization in a typical eight-nucleate sac. : Fic. 25.—Sac containing young embryo; éndosperm and antipodal nuclei BOTANICAL GAZETTE, LII PLATE X BROWN and SHARP on EPIPACTIS THE OXYGEN MINIMUM AND THE GERMINATION OF XANTHIUM SEEDS CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 152 CHARLES ALBERT SHULL (WITH ONE FIGURE) Although delayed germination has received considerable atten- tion during the last few years from investigators both in America and Europe, not much has been accomplished toward solving the problems presented by this phenomenon. This may be due in large measure to lack of exact, or at least quantitative, methods of investigation, and to mental attitude which may modify the interpretation of results. Vitalistic interpretations of phenomena may at times prevent a close analysis of the physical and chemical phenomena which condition the manifestations of life, thus pre- venting the solution of the real problems. During the last two years the writer has been engaged i in an investigation of the relation of oxygen pressure to the germination of Xanthiwm seeds. The need of oxygen for germination and growth of organs in the higher plants has been under discussion for some time. TAKAHASHI (27) has shown that rice can germinate in complete absence of free oxygen, and CROCKER (5) has shown the same to be true for the seeds of certain water plants, as Eich- hornia and Alisma Plantago-aquatica. NABOoKIcH (20) has experi- mented on the hypocotyls of Helianthus annuus, Vicia Faba, and Phaseolus vulgaris, and concludes that the organs of higher plants generally are able to grow in entire absence of oxygen. A rather small number of species was used from which to draw sweeping conclusions. . LEHMANN (18) investigated the anaerobic growth of the organs of higher plants, and found that there is practically no growth in epicotyls at 1 or 2 mm. of atmospheric pressure. In some instances, as with Helianthus annuus, growth of the hypocotyl] occurred in total absence of oxygen in distilled water at a tempera- ture above 25°. In o.5-1 per cent sugar solution, growth occurred even at 20°, but was slight. A number of plants, Vicia Faba, [Botanical Gazette, vol. 52 453] 454 BOTANICAL GAZETTE [DECEMBER Pisum sativum, Brassica Napus, Lupinus albus, and Cucurbita, failed to grow in total absence of oxygen, either in water or in sugar solution, at any temperature. It is evident that the organs of higher plants vary according’ to species in their need of oxygen for growth and germination. The results obtained with Xanthium seeds emphasize this vari- ability, as will be shown later. A preliminary report of this work (26) was published some time ago, since which time the work there outlined has beenlargely completed. The problem was sug- gested by Dr. WitLtAM Crocker, and has been pursued under his direction at the Hull Botanical Laboratory. It is a pleasure to acknowledge my indebtedness to him for many helpful suggestions during the course of the experiments, and for making during my absence from the University of Chicago some accurate determina- tions of the vapor pressure present in the os saienties under experi- mental conditions. Historical The literature on delayed germination has been reviewed so recently by others that a detailed account of the earlier work is not necessary here. Some of the earliest experiments were carried on by NosseE (21) during the decade 1870-1880, in connection with the testing of agricultural seeds. A little later NoppE and HANLEIN (22) tested many weed seeds, obtaining remarkable results; and finally HANLEIN (11) reported on a large number of seeds which he kept in germinative conditions for 1173 days, many of which showed a fraction of 1 per cent of germination, while of Phyteuma spicatum L. and Primula elatior Jacq. not a single seed germinated in that time. These investigators recognized that the testa in some cases excluded water and prevented germination. But when the testa allowed water to enter, which was not infrequent, and still no germination occurred, both writers refer to this phenomenon as an inexplicable “ Ratsel.”’ HANLEIN recognized another category of behavior, however, in which the resistance of the seed to germinative conditions is not external and mechanical, but is internal and protoplasmic. The character of the ovule, the origin, character, and age of the fertiliz- Igit] SHULL—OXYGEN MINIMUM AND GERMINATION 455 ing pollen, the nutrition of the parent plant, accidents of sun and shade, moisture and dryness of soil, high and low altitude, weather conditions during ripening, the time of harvesting, and subsequent handling of seeds are suggested as influential factors in determining germination behavior. The germination of Xanthium seeds was first investigated by ARTHUR (I), who noted the dimorphic character of the two seeds in the bur, and found that the lower seed germinated in the spring after ripening, while the upper seed germinated the second year or later. Believing that the testa was too nearly alike in both seeds to cause this difference, and finding much more reducing sugar in the lower seed than in the upper after exposure to germinative conditions, he suggested that enzymes were produced in the lower seeds more readily than in the upper, and that the delayed nutri- tion of the embryo of the upper seed was the probable cause of the delay in germination. MAsTERMAN (19) tested the germination of Xanthium in some field experiments during several years, and showed that over 90 per cent of the burs grew both seeds the same year, thus contra- dicting the statement of ARTHUR that the upper seed was usually delayed till the second year or later. MAsTERMAN’S experiments were not critical, but the results that he and ARTHuR obtained are readily explained and harmonized in the light of more recent investigation. PamMMEL and Lummis (24) found that weed seeds germinated a much higher percentage of seeds after having been frozen than before. In the case of X. canadense, they found that none of the fresh seeds germinated during the fall, but after freezing and thaw- ing during the winter, over 50 per cent of them germinated. Faw- cETr (7) obtained similar results with many kinds of weed seeds, the percentage of germination being increased, and the “period of dormancy” shortened by freezing again and again. If the upper cocklebur seed is delayed till the second spring or later, it is because it has resisted the forces of disintegration which finally make possible the entry of oxygen in sufficient quantity for germination, or has not experienced the high temperatures which Crocker has shown will cause the germination of uppers with 456 BOTANICAL GAZETTE — [DECEMBER coats intact. Such resistance may be the usual thing in seeds collected and kept at an even temperature during the first winter. But in nature the extremes of winter climate must often destroy the integrity of the coats of these seeds, thus admitting the oxygen necessary for growth. And even if the seed coat is intact, the high temperature often experienced during the spring and early summer is sufficient to germinate the upper seeds if they are near the surface of the ground, since temperatures between 30 and 35°C. cause germination of the uppers with coats intact. Thus it is seen that the results of ARTHUR and MAsTERMAN may both be correct under proper circumstances, and the discrepancy i in | their results is readily accounted for. ; Later CROCKER (4), in testing ARTHUR’s enzyme theory, dis- covered that the cause of delay in the upper seed lay in the seed coat, which, though not excluding water, restricted the supply of oxygen to the embryo to such an extent that growth was tempo- rarily suppressed. He tested many other seeds which showed delayed germination and found that, contrary to the usual opinion, in the majority of cases the coat was responsible for the delay by exclusion or restriction of oxygen or water. He pointed out that the restriction of oxygen for the embryo by the testa gave these seeds an exceptionally high minimum temperature for germination, and that, since the seed coats of uppers and lowers differed in the degree of restriction, two minimum temperatures exist for each seed, one with the coat intact, the other with the coat removed. He suggested that high temperatures caused germination by hasten- ing the diffusion of oxygen through the seed coats; but since it is shown in this paper that a rise of temperature decreases the amount of O, demanded for growth, the question as to the influence of temperature on diffusion in this particular case is an open one. High oxygen pressures brought about germination in a short time, but not in the usual manner. The cotyledons elongate sooner than the radicle, due to the thinness of the testa at the distal end of the seed permitting the diffusion of oxygen more readily over the cotyledons. CROCKER (5) tested seeds of water plants also, and showed that in many instances the delay in germination was due. to coat char- Igr11] SHULL—OXYGEN MINIMUM AND GERMINATION 457 acters, which exclude or restrict the supply of water, rather than to embryonic characters. : At about the same time certain German investigators published a number of papers dealing with similar problems, which are of interest chiefly because of the interpretations of their results. CorRENS (3) found a higher percentage of germination in the disk seeds of Dimorphotheca pluvialis than in the ray seeds. He ascribed the difference in percentage of germination to the different constitu- tion of the embryos, but CrocKEeR showed that in the dimorphic seeds of Axyris amaranthoides the non-winged seeds were delayed by coat characters, and that the percentage of germination did not differ when the coats were broken, both showing too per cent in three days. Ernst (6), working with seeds of Synedrella nodiflora, showed that light of various intensities and refrangibility affected the length of time necessary for germination, and he attributed not only percentage of germination but also the length of time necessary for germination to the constitution of the embryo. FIscHER’s (8) paper on the influence of hydrogen and hydroxyl | ions on seeds of aquatic plants appeared shortly before CROCKER’s work on the seeds of the same plants. Fiscuer interpreted his results as showing that the ions stimulated and awakened the sup- posedly dormant protoplasm to activity, and thus caused germina- tion to occur. But as already intimated, it was shown by CROCKER that the protoplasm of the seeds of these aquatic plants is not dormant, and needs no stimulus except the necessary conditions for germination, which are supplied if the testa is removed or broken. OsTENFELD (23) found that digestive enzymes of birds favored the germination of seeds, but he refrained from ascribing the results to the effect of the enzyme on the embryo, saying that the question raised by the widely different interpretations of FiscHer and CROCKER was an open one. Following the work of Ernst mentioned above, KINZEL (12-16) has shown that light is a factor in the delayed germination of many seeds. The data accumulated show that in some way light of various intensities and refrangibility modifies the seed with the testa intact. The interpretation in all cases ascribes the results 458 BOTANICAL GAZETTE [DECEMBER to the protoplasmic characters of the embryo, which are supposed to be changed so that the seed becomes more active or less active by exposure to light. The uses of such terms as “‘lichtmiide” and ‘“‘dunkelhart” as applied to protoplasm gives one the charac- teristic viewpoint. Very recently GassNER (9, 10) has studied the effect of light on the germination of some South American Gramineae. His interpretation is in harmony with that of K1nzet, the effect of the light being considered as exerted upon the embryo. In none of these recent investigations have the methods been sufficiently refined to locate with certainty the cause of the delay. Before the real truth'in regard to the cause of delay in many of these instances can be ascertained, more exact and analytical . methods of procedure must be brought to bear upon the problem. A careful reinvestigation of some of these cases will not only’ probably locate the causes, but also reveal the nature of the causes of delay. Materials and methods This investigation of the germination of the seeds of X. penn- sylvanicum and X. glabratum was undertaken after the discovery had been made that the oxygen pressure necessary for germina- tion with testa removed was lower than the results CROCKER obtained with them intact would seem to indicate, and with the knowledge that the seeds of some higher plants, as Alisma, Eich- ornia, rice, etc., could germinate in entire absence of free Oz Seeds were collected in various places. Those used during the first season were secured in vacant lots in and near Chicago during the spring of 1909. One lot of seeds had been collected in the autumn as soon as ripe, and were kept in cool dry storage during the succeeding winter and spring. During the second season, seeds were used which had been collected in Lexington, Ky., in November 1909, and kept in an unheated dry room until June 1910. These seeds would all be included in Gray’s X. canadense Mill., but Brirron’s treatment of the genus is certainly more satisfactory than Gray’s, and I use the names X. pennsylvanicum Wallr. and X. glabratum Britton as in the Brirron Manual. I am indebted to Dr. J. M. GreENMAN for examining the seeds and 1911] SHULL—OXYGEN MINIMUM AND GERMINATION 459 permitting me to see and compare my materials with the genus collection of Xanthiwm in the Field Museum of Natural History. a In determining the minimum oxygen pressure required for the initiation of protoplasmic activity, reduction of total atmosphere was employed. The apparatus used at first was a slightly modified form of that used by SCHAIBLE (25) in his experiments on the germ- ination and growth of various plants at reduced atmospheric pressures. In order to control the light, the germinators were at t MoM. Fic. 1.—Diagram of apparatus: a, capillary tube; b, wash bottle; c, two germina- tors with wet cotton, for lowers and uppers; ¢, pressure gauge; ¢, vacuum chamber e low pressure when the germinators are started, f, aspirator run by constant level system with a fall of 45 feet. first surrounded by opaque black paper; but later, when tempera- ture was found to be a very important factor in the result, and while testing the influence of temperature on the oxygen minimum, light and temperature were both controlled by placing the germinators in a water bath provided with a sensitive electric thermostat. A diagram of the apparatus is shown in fig. 1. The seeds were germinated on moist absorbent cotton, and a constant current of air was drawn into the apparatus through long Pieces of capillary tubing by means of powerful aspirators. In order to overcome the drying effects of a low atmosphere, a dish of water was set in each germinator in addition to the saturated 460 BOTANICAL GAZETTE [DECEMBER absorbent cotton on which the seeds lay. This method was dis- carded for the temperature and pressure experiments, as a more satisfactory arrangement consisted in immersing the lower end of the capillary tube in a flask of water, thus drawing the atmosphere through water before it entered the germinator. This method had the added advantage of showing at once whether the flow of air through the capillary tubes was being interfered with by dust particles. The air was kept moist in this way, but owing to the very rapid exchange of gas in the apparatus, the atmosphere was not saturated. The water which ran the aspirators had a fall of 45 feet, and was furnished through a separate constant level system which gave the aspirators uniform power. The seeds were in all cases prepared for experimentation by soaking them in ice water, far below the minimum temperature for germination, for at least 12 hours, after which the testa was removed carefully, without injury to the seeds. ‘They were exposed to constant conditions for 10 days, and the elongation of the hypo- cotyl and the geotropic response was used. as the criterion of germination. Temperature series at various pressures were run at 31 C., and the influence of fluctuating temperature was determined by using a fluctuation of 25—40° C At the low pressures and high temperatures employed, the evaporation of water in the apparatus is very rapid. In determin- ing the actual oxygen pressures to which the seeds are subjected, it is necessary to know what volume of air is drawn through the apparatus in a given time, and what part of the gas pressure is due to water vapor. The atmosphere is not saturated, for if it were saturated at these reduced pressures, the water vapor pressure alone would be much higher than the total pressure used. The amount of air at normal pressure entering the apparatus is 3-5 liters per hour, a very rapid exchange, since it means 8-12 times that volume per hour within the germinators due to expansion under diminished pressure. Under such circumstances it is not surprising to find that the water vapor is removed so rapidly that the satura- tion point is not approached. It was clearly demonstrated, how- ever, that water was not a limiting factor in these experiments. 1911] SHULL—OXYGEN MINIMUM AND GERMINATION 461 Any increase of the aqueous vapor about the seeds was invariably attended by a marked decrease in the percentage of germination and amount of growth, due to the fact that such increase necessa- rily reduces the oxygen supply of the germinating seeds. In spite of the rapid evaporation and removal of the water, there is suf- ficient moisture present to bring about all the growth changes which the oxygen supply will permit, as was shown by repeated tests. In correcting the pressures for water vapor, the only practicable method is to measure directly the amount of dry air passing into the apparatus per hour, and the amount of water vapor drawn from it in the same length of time, then calculate the proportion of each gas in the gram molecular volume. A concrete example will make the method clear. At 88 mm. pressure, 30° C., the dry air drawn through the apparatus measured at 20° C., barometer 745 mm., is 4.37 liters per hour. Reducing this volume to standard tempera- ture and pressure gives 3.9 liters. This volume is 0.178 of the molar volume. The amount of water vapor present with that amount of air drawn from the apparatus as determined by phos- Phorus pentoxide absorption was 1.65 grams per hour; and this amount is readily found to be 0.086 of the molar volume. The dry air and water vapor together amount to 0.264 of a mole per hour. The pressure recorded by the manometer is 88 mm. Of this amount, 178/264 (59.3 mm.) is air pressure, 86/264 (28.7 mm.) aqueous pressure. The oxygen pressure is then readily obtained, as oxygen constitutes 20.93 per cent of the atmosphere. The correc- tions were made on the basis of the average of three determinations, and are therefore fairly reliable. To determine whether reduction of pressure per se has any effect on germination, hydrogen gas with a low oxygen content was admitted to the chambers containing the seeds. The hydro- gen was imported by the Linde Air Products Co., of Buffalo, N.Y., and was found to contain 2.34 to 4.7 per cent of oxygen. The gas with more than 2.5 per cent of oxygen was of little use, because the oxygen pressure was so high that no comparison with the reduced pressure experiments could be made. This hydrogen was under 120 atmospheres of pressure, but was controlled by high 462 BOTANICAL GAZETTE [DECEMBER pressure valves so that a small stream of gas at normal pressure ran constantly through the germinators. The gas was washed by passing it successively through potash bulbs containing concentrated potassium permanganate solution, and 33 per cent potassium hydroxide. The whole series of coils and jars was packed in ice for 12 hours after the hydrogen began to flow, and the gas was carefully analyzed by phosphorus absorp- tion until it was found to be coming from the apparatus with as low oxygen content as when taken directly from the tank, at which time the temperature was allowed to rise sufficiently for germina- tion. In this way the possibility of the initiation of germination in only a partially replaced atmosphere was precluded. The appara- tus was quickly brought to ordinary temperature, and kept con- stant at 21.5° C. by allowing a current of water from Lake Michigan to flow over and around the potash coils and germinators. Re- duced atmosphere experiments at the same temperature were run at the same time, but the correction for water vapor in these series makes a direct comparison with the results in hydrogen impossible. However, comparison of these hydrogen results with other low pressure series run in the same way, makes it possible to draw trustworthy conclusions. Attempts were made to test the after-ripening of Xanthium seeds of different ages, from green to a year old, at normal and reduced pressures. These experiments were not extensive, and. on the whole not very satisfactory; but the results indicate that only very slight changes occur. : In all cases control cultures were employed. In measuring the growth of the controls, a difficulty presented itself. At full atmospheric pressure the roots of Xanthium seedlings penetrate the substratum of cotton with innumerable branches, impossible of disentanglement and accurate length measurement. In all these cases only the unbranched portion of the plant was measured. In all the experimental plants the total growth in length was easily measured and is so recorded. Experiments : As indicated above, the experiments proceeded along four lines: to determine the minimum oxygen pressure necessary for germina- *. tg1r] SHULL—OXYGEN MINIMUM AND GERMINATION 463 tion, and to determine the influence of temperature, pressure, and after-ripening on that minimum. Since the first of these determi- nations is that on which the others bear, that portion of the work will be considered immediately. THE MINIMUM OXYGEN PRESSURE The tabulated results of these experiments are given in the preliminary report, but for convenience they are presented here again, with one addition, a test with X. glabratum (all others are X. pennsylvanicum) at 85 mm., and with correction of the oxygen pressure for aqueous vapor. TABLE I DURATION OF EXPERIMENTS IO DAYS PERCENTAGE GROWTH IN “arts OF A ai “a GERMINATION HYPOCOTYL (MM. grou ous. | PHERic —— TEMPERA- PRES- = TURE ee ee ome | | a ele Petal by eT ele mer | oe FL Ri eis £1 TRIS a1 0O)) bie khe to ele 99..... 16.4 | 82.6 | 17.3 9-22 |75.0/100 |45 | 95/14.5 | 30-0 | 4.9/23.3 90..... 3 | 73-7 | 15-4. | 21-22.680.0) 95 [50 |100/22.8 | 45.9 | 4.3/37-8 eG 6.25] 68.75) 14.39) 21.5 (56.6) 93.3/23.3/100)42.8 |103.64/10. 5194.9 72* 16.14} 55.86] 11.69} 20-28 (45.0/100 |20 |10011.5 | 46.0 | 9.4/33.6 (ee 16.14) 55.86] 11. 20-22 |30.0| 95 | © |100 6.36) 28.5 | 0.0)/22.0 28*....| 15.27| 12.73| 2.66|21.5-24.5) 0.o|100 | oO | g5| 0.0 | 37.8 | 0.0/28.8 * Temperature not controlled. The table shows at once that there is a marked difference between the upper and lower seeds in percentage of germination and amount of growth under identical conditions, this difference being the expression of a decided difference in the oxygen need of the two seeds for germination. The difference in percentage of germination at each pressure and temperature used is fairly constant, the lowers germinating about 30 per cent more seeds than the uppers in each experiment. The difference in the oxygen need is several milli- meters, the lowers requiring less oxygen than the uppers for the initiation of activity. The oxygen minimum for the uppers is approximately 12 mm., at 21° C., while the minimum for the lowers is about 9.5 mm. It is important to notice the relation which this physiological difference in the embryos of the two seeds bears to the difference 464 BOTANICAL GAZETTE [DECEMBER in their seed coats. CROCKER found that restriction of the oxygen supply by the testa was the main cause of delay in germination, and that difference in the degree of exclusion by the testa of upper and lower seed accounted for the difference in delay of the two seeds. But this embryonic difference, which is clearly demonstrated in the table, acts in conjunction with the coat differences in securing a longer delay in the upper than in the lower seeds. In comparison with the seeds and organs of other plants, the oxygen demand of Xanthium seeds is very high. As already noted, most seeds will germinate with not more than a few milli- meters of atmosphere, and some germinate without free O,, but Xanthium requires g-12 mm. of oxygen, the equivalent of 44-60 mm. of atmosphere. This high demand for oxygen aids in secur- ing delay, for if only a small fraction ofa millimeter were needed for germination, the testas might not restrict the supply sufficiently to cause delay. And the difference in demand of the two seeds would secure a longer delay for the uppers than for the lowers, even if the testas did not differ in their power to exclude oxygen from the embryos as they do. : TEMPERATURE AND THE OXYGEN MINIMUM It was found that temperature is a powerful factor in determin- ing the oxygen minimum, slight changes producing marked effects upon the results. The potent influence of temperature in this regard is shown clearly by the two lots of seeds of X. pennsyl- vanicum kept at a pressure of 72 mm. as recorded in table I. The variation noted in these two lots was due to one lot being subjected to a temperature 6° higher than the other during a part of the last two days of the experiment. Previous to that time, the behavior of the two lots of seeds had been almost identical; but 45 per cent of the lowers germinated in the lot which reached 28°, as compared with 30 per cent, the lot which did not go above 22°; and 20 per cent of the uppers germinated as compared with complete failure to germinate at the lower temperature. The amount of growth in each lot shows a similar relationship. In- another instance shown in table I, two lots of seeds were subjected to atmospheric pressures of 90 and 99 mm. respectively, Igir] SHULL—OXYGEN MINIMUM AND GERMINATION 465 but the latter lot was subjected to a temperature 2° lower on the average than the former. The results show, instead of an increase in percentage of germination and growth in length, as would have been expected from the increased supply of oxygen, a decrease of 5 per cent in the germination of both lowers and uppers, and a considerable decrease in the average growth of the lowers in length. A number of experiments were performed with the purpose of determining how much effect temperature has on the location of the minimum. The results are presented here in tabular form. For the sake of comparison, one experiment at 72 mm. and room temperature is included at the bottom of the table, which may be compared with the results at 76 mm. and 31°, and with those at 75 mm. and 25-40". TABLE It DURATION OF EXPERIMENTS IO DAYS PERCENTAGE OF GROWTH IN LENGTH OF Manom- | Vapop | ATMOS- vena B GERMINATION HYPOCOTYL (MM.) a : s s a ancy | Gacy | ER | ood | BLE RIE) BLE BI SE %, = c =I a | PeTs clele siolete Tees 29.0 | 47.0 | 9.8 31 |93.3/100 \40.0 100 |50.4 102.0 32.75)109.0 no eee 90.2% |. 38.90 | 7-5 31 |60.0/100 |43.3|/100 |33.1 |102.0 20.15/109.0 ee 99;0 155.6 1 95 31 |80.0/100 |10.0/100 /32.4 | 79.6 24.00) 86.6 ce eee 25.7 | 30-97). 6.8 31 |66.6)100 | 0.0/T00 |11.6 | 79.6) 0.00) 86.6 eee Varies) with |temp. |25-40 (93.3) 90 |56.6)100 |37.25 67.4/28.00) 70.6 ee Varies with |temp. |25-40 |86.6) 90 (26 6\I00 |32.9 | 67.4/17.25| 70.6 fies pae 16.4 | 55.86) 11.69/20-22 | 30 | 95 | 9.0)/I00 | 6.36 28.5, G16 | 22.0 The difference between uppers and lowers in percentage of germination is even more pronounced at 31° than at 21°, amount- ing in some instances to 60 or 70 per cent more germinations among the lowers than among the uppers. It appears also from table IT that the oxygen minimum is considerably lower at 31° than at 21°, especially for the lower seeds. From the data here presented the oxygen minima have been approximated by mathematical methods. Since a pressure of 65 mm. germinated 10 per cent of the uppers, the oxygen minimum as calculated from the results would be about 6.75 mm. The minimum for the lowers was not accurately deter- mined, but at 55 mm. atmospheric pressure, representing an O, 466 BOTANICAL GAZETTE [DECEMBER pressure of 5.5 mm., there was still 66.6 per cent of germination. The closest estimation possible from the data at hand would indicate an oxygen minimum of about 2.5-3.5 mm. for the low- ers at 31°. The lowering of the minimum is somewhat greater in the lower than in the upper seeds. The oxygen minimum of the uppers is decreased from about 12 mm. to less than 7 mm., while for the lowers the minimum is decreased from 9.5 to about 3 mm. All of these results show that with the increase of temperature there is a decrease in the demand for free oxygen. The probable reason for this will be discussed later. The physiological difference of the embryos of the upper and lower seeds is shown clearly by these experiments, the embryo characters being just as strikingly differ- ent as the coat characters; and both sets of characters act together in securing the difference in delay of the two seeds. Temperatures fluctuating between 25 and 40° are apparently no more effective in producing germination than the constant high temperatures employed. Since the pressure in the germinators remains constant while the vapor pressure fluctuates with the temperature, it is evident that the oxygen pressure fluctuates also, and that its fluctuation is inversely as the temperature, rising as the temperature falls, falling as the temperature rises. CROCKER found such fluctuating temperatures more effective in producing germination than constant temperature of 35° in the upper seeds with testas intact. The fluctuation may render the testa more permeable to oxygen, but in view of the effect of temperature on oxygen demand, the inference cannot be made with certainty. A peculiar result was observed in all the control experiments at high temperatures. At normal room temperature, both the experimental seeds and the controls show less growth in the uppers than in the lowers; but at high temperatures, whether constant or fluctuating, this relation is reversed in the controls. This is noticed on comparison of lower and upper controls in table II. At the same time, both lowers and uppers of the experimental seeds show less growth in a fluctuating temperature of 25-40° than cor- responding lowers and uppers at constant high temperature of ae and equal pressures. The first two experiments in table II, com- Ig11] SHULL—OXYGEN MINIMUM AND GERMINATION 467 pared with the two fluctuating experiments in the same table, show this to be true. The decreased growth in the fluctuating temperature in this case is possibly due partially to the decreased oxygen pressure in the germinators as the vapor pressure increases with the rise in temperature. PRESSURE AND THE OXYGEN MINIMUM The method employed in these experiments has been briefly described, and the results are recorded in table III. Parallel experiments at reduced pressure were run along with the hydrogen tests, the germinators being kept in the same running water at a pressure of 85 mm. The oxygen pressure in the hydrogen and reduced pressure experiments would have been the same but for the aqueous pressure in the latter. The correction for water vapor reduces the O, pressure from 17.79 mm. to 14.39 mm., a large enough difference to make the results not directly comparable. The first three tests were with X. pennsylvanicum, the remainder with X. glabratum. The first of these hydrogen tests is of little value in determin- ing the effect of pressure on the oxygen minimum, for the oxygen content was 35.25 mm., or more than double that used in any of the reduced atmospheres. Only a slight reduction of the growth is brought about, which would indicate that this amount is prob- ably somewhat below the optimum oxygen pressure for Xanthium. Nagpoxicu has shown that the atmosphere contains considerably more than the optimum oxygen supply for growth in higher plants. On comparing the results of the remaining hydrogen tests with those at reduced pressures, it is seen at once that there is a higher percentage of germination, and a greater average growth in the hydrogen than in the reduced atmosphere. For instance, in hydro- gen 96.6 per cent of the lowers, and 43.3 per cent of the uppers of X. pennsyloanicum germinated, as compared with 26.6 per cent of the lowers and 23.3 per cent of the uppers in the 85 mm. atmosphere. X. glabratum shows a similar behavior, 56.6 per cent of the lowers, and 23.3 per cent of the uppers germinating in the reduced atmos- phere. Is this difference due to a difference In oxygen pressure [DECEMBER BOTANICAL GAZETTE 468 v°zg o'9z | z'gg 1'gt oor | €'f1 oor | 0°06 o-ee | 6f*rr $£°g9 $z‘gt ke tee Ae ee 42g o'61 | 2°98 o'be OO fy ERE Gor | 2-25 o-ez | G6E:rz $L°g9 Sz*gr aoe SAL 2 ee $°zQ zfP | z°99 g Ll cor | o'of oor | £°E6 Oeey Solr {se Lis vez 6° +6 S-or |vg'for | g'zr oor | €°8e') £66) ges Sie]. GE i $L°g9 S€-g1 ae tte ae 6°46 6°€€ |vg° for I'9f oor £°Ez £°£6 | g'gz S*1z 6 +1 SL°g9 Sz°gI yaa ‘Stee 6° +6 o'lv |g for | gig OO1 | 2 EP £776 GGG Ts ee ar iste re Ez o’Sor | Sc'6g | g*101 | £76 | Efe] £°86) g'og|] £°86 |S:ez-S-1z | Sz-S€ ee? oe oL*¥ sforjuo_ | stoddq | sjomjuod | siamoy | sjorjuoD | szeddq | sforzuo0g | siamoy (70) (9) (KR) | aanssaua (UR) NADORGAM. (OX) ‘WN) ‘TALOQOdAH veeckny, RAKED enone oamaby ‘oo. eases aEUENCAY Se Pe cia NI HLMOWO ZOVaEAY NOILVNINUAD JO AOVINGOUT -SONLY SAVG OI SINGWIMAdXA JO NOLLVANC I ATAVL ToII] SHULL—OXYGEN MINIMUM AND GERMINATION 469 alone, or does the difference in pressure as such have a part in pro- ducing this effect? Comparison of the results in hydrogen gas with those at 90 and 99 mm. in table I, which approach most nearly the same oxygen pressure, shows that the difference is probably nearly all due to difference in oxygen pressure, rather than to a difference in barometric pressure. It is possible that great reduc- tion in pressure may affect slightly the percentage of germination and the amount of growth. WUIELER (28) came to the conclusion that growth is independent of pressure; and SCHAIBLE (25) ob- served that reduced pressures increase the rate of growth, but that - the influence of air pressure on germination is very slight. From the data of table III, as compared with the results of the other experiments, it appears that the oxygen minimum is prac- tically the same for any given temperature, whether the reduction is accomplished by reducing the atmospheric pressure, or by dilu- tion with inert gases like hydrogen. AFTER-RIPENING OF XANTHIUM Several attempts have been made to test the after-ripening of Xanthium seeds, with the results here briefly recorded. During October and November 1910, I made a test of the germination of X. glabratum at normal pressure, average temperature 23° C., at Transylvania University. Seeds in three different stages were taken as follows: green seeds, so young that the testas were still quite white; seeds which had ripened normally on the plants in 1910; seeds collected in the same locality in 1909. The seeds were prepared for germination as in all the other tests, and the integu- ments removed carefully. The results show that, at normal pres- sures at least, the protoplasm does not pass from an inactive state to an ultimately more active one, and that there is no after- ripening in that sense. The seeds averaged as follows in growth in length: Lowers - - Uppers IQIO green SCEUS.. 1.2.4. essneees 46.0 mm, 37.0 mm. 36.0 mm. 31.5 mm 1910 brown seeds. .....--++++++++- 1909 brown seeds.......-+-+-++-+:- 34.3 mm. One experiment with fresh seeds at reduced pressure agrees with these results. The seeds were kept at 90 mm. pressure, tempera- 470 BOTANICAL GAZETTE [DECEMBER ture 21.5°, December 2-11, 1909. In this case 96 per cent of the lowers, and 33 per cent of the uppers germinated; and the lowers averaged 30 mm. in length, the uppers 1omm. The controls were injured in some way, but all had germinated. A comparison of these figures with those at 90 mm. pressure, temperature 21-22.6° (table I), using seeds almost a year old, shows that fresh seeds have as high a percentage of germination and a more rapid growth than the old seeds under reduced pressure. In another experiment, however, seeds collected green in 1910 were tested along with seeds a year old, and no germination was secured at 90 or 100 mm. pressure, at 21°, in either crop of seeds. In the controls growth was fine, and the 1910 seeds showed a better growth than the 1909, just as reported above for seeds eerie under the same conditions. It is possible that the after-ripening manifests itself in a cae either in the lowered demand of the embryo for oxygen, or in an increased permeability of the coats to oxygen, or in both at once, the change being too slight to affect the results at normal pressure. Some experience with these seeds in laboratory exercises in the Hull Botanical Laboratory lends force to this suggestion. With freshly ripened seeds having the testas intact, the classes fail to get the usual cotyledonary germination in pure oxygen atmosphere, as was reported by Crocker for the upper seeds of X. canadense after 6 days at 21-23°; but in the winter, several months after ripening, these same seeds gave good cotyledonary germination in pure oxygen. This experience indicates either a decrease in the demand for oxygen by the seed, or an increase in the permeability of the seed coats as ripening progresses, and corroborates the evidence furnished by the experiments on after-ripening. It is clear from these experiments that there is a slow progres- sive deterioration of the seeds, manifested in the reduced growth of the seeds as they become older, which after a few years probably causes entire loss of power to germinate.. This deterioration seems to be a little more rapid in the lowers than in the uppers, but the physiological difference of the two seeds was very evident in the oldest seeds, and no doubt remains so long as they will germinate at all. SHULL—OXYGEN MINIMUM AND GERMINATION 471 Discussion The methods employed in much of the recent work on delayed germination of seeds has not been as exact as is desirable, or even necessary, for the solution of the problems involved in this phenome- non. ‘The factors which are influential in the germination behavior have been investigated qualitatively only, without any attempt to measure them accurately and determine their relations. Moreover, the seed has been regarded too often as an embryo only, which may be affected profoundly by chemical and ethereal stimuli, the testa being considered as negligible on account of its thinness or on other insufficient grounds. In K1nzev’s latest paper (16) he claims to have met all the serious criticisms made against his work, but in none of his experiments has he eliminated the testa as a factor. Recently LEHMANN (17) has shown that other stimuli than light can be substituted in its place and produce approximately the same effect. For instance, he found that the effect of 1 per cent Knop’s solution in the germination of the seeds of Ranunculus sceleratus was much the same, inducing practically the same percentage of germination. If such substitutions of stimuli are possible, what can be stated with certainty as to the cause of delay in these cases ? Light and the chemicals undoubtedly affect something, but it may as easily be the testa as the embryo that is changed. Even if the effect is actually produced in the embryo in these instances, the phenomena are not explained by saying that the protoplasm has been rendered “lichthart”’ or “‘lichtmiide,” as if it were a sort of “weariness of the flesh!’ If there is a change in the permeability of the embryo, or other physical or chemical alterations in it which leads to activity or cessation of activity, demonstration of such changes would throw some light on the phenomena. In these Xanthium experiments the determinations have been made with as great exactness as possible, the accuracy lying well within the variability of the seeds themselves, and the work has been almost entirely quantitative. These methods demonstrated clearly the physiological difference between the embryos of the upper and lower seeds, although the difference is so slight as not to affect visibly the germination of the uppers at atmospheric pres- sure when the testa has been removed. This fact shows the value 472 BOTANICAL GAZETTE [DECEMBER of the quantitative method. It may reveal differences existing in various parts of the seed, which would otherwise remain undis- covered, and may in this way lead to results of the highest signifi- cance in the explanation of delay in germination. Often only quantitative measurements can detect the factors which determine the peculiarities of behavior. The oxygen pressure needed to initiate germination in Xanthium seeds with coats removed is considerably less than would be expected in view of the rapid exchange of gases which CROCKER found in these seeds with testas intact. However, the amount necessary is large in comparison with the oxygen supply needed by seeds of many other angiosperms. The question as to whether higher plants can grow in absence of oxygen has been much dis- cussed recently. Attention was called to the results of TAKAHASHI on rice, of CRocKER on Alisma and Eichhornia, of NaBoxicH and LEHMANN on the organs of the seeds of many higher plants, in the introduction to this paper. Nasoxicu believes that the organs of nearly all seeds of higher plants can grow in absence of free O:. Xanthium seeds would certainly have afforded him a remarkable exception. It is much more probable, from the data now before us, that the seeds of the higher plants vary largely in the amount of oxygen required for germination, some of them, like Alisma Plantago-aquatica, rice, and other seeds which grow in media containing little free oxygen, requiring no free oxygen whatever; others, like Xanthium, requiring a comparatively large amount; with perhaps the great majority of seeds lying somewhere between them in regard to oxygen need. Such seeds as water plantain stand at the one end of the series, and Xanthium perhaps at the other extreme, with all possible intergradations. The exper! ments which have been carried on with Xanthium show that some seeds require a comparatively large amount of free oxygen, thus making each species of seed a problem in itself. There is no one behavior for the seeds of all higher plants, as NABOKICH seems to believe. There are several facts which need to be considered in connec- tion with the apparent inconsistency between the results I have obtained with Xanthium seeds as to the need for oxygen when the tgtt] SHULL—OXYGEN MINIMUM AND GERMINATION 473 testa has been removed, and those obtained by Crocker with the same kind of seeds with the testa intact. When the seeds with testas on are allowed to germinate normally, the hypocotyl always elongates first and the root is well developed before the cotyledons begin to grow. That is, there is a strong correlation between the growth of these two organs of the seed. But if the well ripened seeds with coats on are germinated in an atmosphere containing a high percentage of oxygen, the cotyledons instead of the hypo- cotyl initiate the development of the embryo. The strong normal correlation is reversed by temporary suppression of the hypocotyl, due probably to a more rapid diffusion of oxygen through the very thin distal portion of the testa surrounding the cotyledons than through the thick proximal portion which invests the hypocotyl. The cotyledons thus receive the necessary free oxygen for germina- tion sooner than the more sensitive hypocotyl, with the result that the usual course of growth in the seed is completely changed. This reversal of a very strong correlation probably requires considerably more oxygen than a normal germination. Not only is the usual behavior overcome, but the part which grows instead of the hypocotyl is a much less sensitive part of the embryo, undoubtedly requiring more oxygen to initiate its activity. In animal cells food storage renders the protoplasm inert, and delays cell division to a very marked degree. It is possible that food storage in the cotyledons has a similar effect on their activity, requiring more energy, and therefore more oxygen, for the growth processes. Another factor probably responsible for a considerable portion of the gaseous exchange during germination with the seed coats intact is the testa itself. BECQUEREL (2) has shown that the integuments of seeds produce CO, in comparatively large amounts, sometimes greatly exceeding the seeds from which they have been taken in CO, production. For instance, he found that one gram of Ricinus integuments exposed to light gave off 18 times more CO, than one gram of seeds with testas removed; that one gram of the testas of Vicia Faba gave off 10 times as much CO, as the same weight of decorticated seeds; and that one gram of the coats of the pea produced 25 times as much CO, as a gram of the embryos. 474 BOTANICAL GAZETTE [DECEMBER In CROCKER’S experiments the measurement of the gaseous exchange was made for seeds with testas on, and therefore included whatever coat CO, production occurred. And, since the thickness of the testa over the hypocotyl practically excludes the oxygen from that organ, while the thinner distal portion of the coat admits the oxygen to the cotyledons first, thus initiating the cotyledonary germination mentioned above, the measurement of the gaseous exchange has dealt very largely with that occurring in the coty- ledons. In my experiments the removal of the coats eliminates the coat CO, production; and, since the cotyledons never grow under the conditions of the experiment until after the hypocotyl — has elongated, the determination of the oxygen minimum is made for the hypocotyl only. There is no inconsistency, I believe, between the results obtained by Crocker and those obtained in these experiments. Indeed, the unusually high minimum for the decorticated seeds agrees well with the data secured in earlier determinations with the coat intact, when the coat CO, produc- tion and the reversal of the correlation between hypocotyl and cotyledons are taken into consideration. The lowering of the oxygen minimum by increase of temperature is at least partially accounted for by the increase in anaerobic respiration as the temperature rises. On the other hand, if a constant free oxygen supply below the optimum is maintained during a rise in temperature, the growth capacity of the organism is increased as the temperature rises. It is known, also, that merely cutting off the supply of oxygen will increase the anaerobic respira- tion in many organisms. With the oxygen reduced to a minimum, and at the high temperature employed, the conditions in these experiments are favorable to a considerable increase in the anaerobic form of respiration. As the anaerobic respiration increases, there is less need of the aerobic to release the energy sufficient to initiate growth. The question then naturally arises whether the lowering of the oxygen minimum by increasing the temperature really indicates any difference in the amount of respiration occurring. It is possible that the total energy release necessary for the germina- tion of the seed is practically the same at any given temperature, _ the variation being in the proportion of release due to aerobic 1911] SHULL—OXYGEN MINIMUM AND GERMINATION 475 and anaerobic respiration. This question can be answered only by further investigation. A detailed study of the permeability of the seed coats of Xan- thium to oxygen and other gases and reagents will be carried on, with the purpose of determining whether BECQUEREL’s conclusions regarding the réle of dry seed coats have general applicability. The necessity for more exact quantitative studies of the factors which cause delayed germination is emphasized by this work. The factors which cause specific behavior of the seed are sometimes very minute and may escape detection entirely unless the methods employed in investigation are adapted to that end. The most refined methods of quantitative study are best suited to this purpose, and for a further advance with the problems of delayed germination it will be necessary to adopt the most exact and rigorous methods of analysis. Summary 1. The naked embryos of the dimorphic seeds of Xanthium exhibit a marked difference in their demand for oxygen for germina- tion. 2. The oxygen minimum for the germination of decorticated Xanthium seeds at 21° C. is approximately 12 mm. for the upper seeds, and about 9.5 mm. for the lowers. 3. Increasing the temperature decreases the minima, a rise of 10° from 21° lowering the necessary minimum of oxygen from 12 mm. to approximately 7mm. for the uppers, and from 9.5 mm. to approximately 3 mm. for the lowers. 4. Variation of the total atmospheric pressure probably does not influence the oxygen minimum for germination. The experi- ments indicate that equal partial pressures of oxygen produce approximately the same effect on the seeds, regardless of the total pressure of which it forms a part. 5. There is very little after-ripening, or at least the after- ripening is not visible in an altered germination behavior at atmos- pheric pressure and ordinary temperatures. There is evidence either of a decrease in the oxygen need, or an increase in the permeability of the coats to oxygen, or both, as ripening progresses. 476 BOTANICAL GAZETTE [DECEMBER 6. A very slow progressive deterioration of the seeds takes place, which after a few years causes entire loss of power to germinate. 7. The general conclusion that the organs of the seeds of higher plants can grow in entire absence of free oxygen is not supported by the results obtained with Xanthium seeds. They cannot grow without comparatively large amounts of free oxygen. 8. The oxygen pressures required for germination of Xanthium seeds are very much higher than those reported by LEHMANN for the epicotyls of such plants as Helianthus perennis, Zinnia elegans, and Glyceria fluitans. g. Since the coats cause delay by excluding oxygen, we might expect to find the oxygen demand for growth high. Xanthium seeds stand at the opposite end of the series from the seeds of certain aquatic plants, as water plantain and rice, in demands for oxygen for germination. 10. The high oxygen demand, and the difference in this demand in the two seeds, act with the coats to secure delay, and a difference in delay, in the two seeds. But if the coat has been removed, the demand for oxygen by the embryo is too low to be significant in securing delay in germination. TRANSYLVANIA UNIVERSITY LexrncrTon, Ky. LITERATURE CITED 1. ArTHur, J. C., Delayed germination in the cocklebur and other paired seeds. Proc. Soc. Prom. Agric. Sci. 16:70-79. 1895. : 2. BECQUEREL, Paut, Recherches sur la vie latente des graines. Ann. Scl. Nat. Bot. IX. 5:193-320. 1907. 3- Correns, C., Das Keimen der beiderlei Friichte der Dimorphotheca plu- vialis. Ber. Deatich, Bot. Gesells. 24:173-176. 1906. 4. CROCKER, WILLIAM, 3 of seed coats in delayed germination. Bot. GAZ. 42:265-291. 1 *, of ean gt of the seeds of water plants. Bort. Gaz. 44:375-38°- 1907. 6. Ernst, re Das Keimen der dimorphen Fruchten von Synedrella nodt- flora (L.) Gris. Ber. Deutsch. Bot. Gesells. 24:450-458. 1906. 7- Fawcett, H. S., The viability of weed seeds under different conditions of treatment, and a study of their dormant periods. Proc. Iowa Acad. Sci. PP. 25-45. 1908. 8. FiscHer, ALFRED, Wasserstoff und Hydroxylionen als Keimungsreize. Ber. Deutsch. Bot. Gesells. 25: 108-122. 1907. Tgtr| SHULL—OXYGEN MINIMUM AND GERMINATION 477 © Lal ~I . GASSNER, GusTAv, Ueber Keimungsbedingungen einiger stidamerikani- scher Gramineensamen. Ber. Deutsch. Bot. Gesells. 28:350-364. rg10. , Ueber Keimungsbedingungen einiger siidamerikanischer Gramine- etiesmen. Ber. Deutsch. Bot. Gesells. 28: 504- 512. IQIo. - HANLEIN, H., Ueber vi imkraft von Vidvcutiniend Landw. Ver- Seder “7 465-470. NZEL, WILHELM, Ueber ie Einfluss des Lichtes auf die Keimung. “Lichtharte” Samen. Ber. Deutsch. Bot. Gesells. 25:631-645. 1907. ——., Die Wirkung - Lichtes auf die Keimung. Ber. Deutsch. Bot. Cesclle, 26a: 105-115. I , Lichtkeimung. Tinige bestatigende und erginzende Bemerkungen zu den vorliufigen Mitteilungen von 1907 und 1908. Ber. Deutsch. Bot. Gesells. 26a:631-645. 1908. Lichtkeimung. Weitere bestatigende und erginzende Bemer- kungen zu den vorlaufigen Mitteilungen von 1907 und 1908. Ber. Deutsch. 8. Bot. Gesells. 26a:654-6 6 5. 190 ichtkeimung, Erlauterung, und Erginzungen. Ber. Deutsch. Bot. Gesells. 2'7: 536-545. 1909. . LEHMANN, Ernst, Zur Keimungsphysiologie und -biologie von Ranuncu- lus sceleratus L. und einigen anderen Samen. Ber. Deutsch. Bot. Gesells. 27:476-494. 19009. 8. ———, Zur Kenntniss des anaeroben Wachstums hodherer Pflanzen. Jahrb. Wiss. Bot. 49:61—90. 1grt. MastTermaN, E. E., Notes on the cocklebur. Ninth Report Ohio State Acad. Sci. pp. 20, 21 1900 - Nazoxicu, A. J., Ueber die Wachstumsreize. Beih. Bot. Centralbl. 26:7- - 140. TgIo NoBBE, F, Handbuch der Samenkunde. Berlin. 1876. HANLEIN, H., Ueber die Resistenz von Samen gegen die aserok Facile der Keimung. Landw. Versuchs-Stat. 20:71-96. 1877. . OSTENFELD, C. H., Bemaerkninger i anledning af nogle forség med spire- evnen tos fré, der har passeret en fugls fordéjelsesorganer. Svensk Bot. Tidsk. 2:1-11. 1908. Pammet, L. H., and Lumuis, G. M., The germination of weed seeds. Proc. Soc. Prom. Agric. Sci. pp. 89-92. 1903. ScuarBLE, Fr., Physiologische Experimente iiber das Wachstum und die Keimung einiger Pflanzen unter vermindertem Luftdruck. Beitrige Wiss. Bot. 4:93-148. 1900 . SHULL, CHas. A., Oxygen pressure and the germination of Xanthium seeds. Bot. Gaz. 48:387-390. 1909. Takaunasut, T., Is germination possible in absence of air? Bull. Coll. Agric. Tokyo 6:439-442. 1905. WieteEr, A., Die Beeinflussung des Wachsens durch verminderte Partiir- pressung dos Sauerstoffs. Unters. aus dem bot. Inst. Tiibingen 1. 1881- 1885. Peint ER ARTICLES A PROTOCORM OF OPHIOGLOSSUM (WITH ONE FIGURE) In October 1908, Dr. CHARLES R. BARNES and the writer, while collecting bryophytes in a little known region of Mexico, botanically speaking, on the eastern edge of the great central plateau, about 150 miles northeast of Mexico City, on the boundary of the states of Hidalgo and Puebla, found great quantities of an Ophioglossum, which was distributed as O. Pringlei Underwood by the late Dr. C. G. PRINGLE." The plants were in such numbers and varied so much in size that some days were spent in a thorough exploration of the region, hoping to find gametophytes. Of many hundred small plants, only one showed any- thing resembling a prothallus. After returning to Chicago, this sup- posed prothallus was sectioned and found to be a protocorm. The protocorm, buried in the soil to a depth of 5 cm., is almost . spherical and 9 mm. in diameter (fig. 1), with a slightly roughened surface caused by the irregular collapse of dead cells of the outer cortex. The leaf, including the petiole, is 13.5 cm. long, and shows no trace of a fertile spike. The remains of the leaf traces of five other leaves are present, showing that the protocorm is at least seven years old. e growing point is sunken in a pit made by cortical upgrowth. Numerous rootlets are penetrating the cortex in all directions, but only three or four in the upper region of the corm have reached the soil, and have partly decayed. The outermost cells of the cortex have lost their con- tents and collapsed, forming a protecting layer. These empty outer cells, as well as those of the partly decayed rootlets, are infested with fungal hyphae, which, however, do not enter the living cortical cells. The cells of the cortex are very full of starch. *The specimens were submitted to Dr. J. M. GREENMAN, who has made the following statement in reference to them: “Upon comparison of the material in collections determined as O. Pringlei with known species of this genus, I am unable to find a single character to separate it from our northern species QO. vulgatum L. So far as I can find, O. oulgatum never has been definitely recorded from Mexico, but we have it represented from different stations from Canada and Maine to Arizona, and it would not be unparalleled by other cases to have it turn up in Southern Mexico. I should be inclined, therefore, to regard these Mexican specimens as conspecific with G, Si ag LL Botanical Gazette, vol. 52] | [478 \ 1911] | BRIEFER ARTICLES 479 It was noticed that the plants with few exceptions were in groups of 3-10, usually radiating from a large plant. When the root system of these groups was laid bare, a work of no little difficulty because of the depth of the roots and the great number of roots of other plants in the soil, it was found that nearly all of the plants of a group were connected, and that the smaller plants were produced by adven- titious budding of the roots of the larger plants. This method of vegetative reproduction is found in several species of Ophioglossum. Occasionally a leaf bears two fertile spikes. _ The presence of a protocorm, and a method of vegetative reproduction so similar to Phyl- loglossum, may lead the unwary, or the “arm chair” botanist, to speculate concerning a pos- sible relationship between Ophioglossales and Lycopodiales. It must be borne in mind that the protocorm probably has no phylogenetic significance whatever. The region is one of exceptional interest to a botanist. The great central plateau falls sharply away to the low plain bordering the Gulf of exico. Rain and mist are abundant even in the dry season, because the clouds drift against the high eastern escarpment of the plateau. The border of the plateau is deeply dissected by the numerous small streams which fall over its edge and form box cafions, sometimes 500 meters deep. Because clouds continually drift up these Cafions, their walls and floors are covered with dense masses of filmy ferns, liverworts, and mosses. On the high mesas between these cafions, but never in them, this Ophiogl i tab t ; 5 In the same situation Lycopodium clavatum and : L planatum are alsoabundant. The species of Lycopodium and Ophioglossum are apparently confined to an altitude of about 2200 meters. At the same altitude, on the bank of a stream just before it plunges over the wall of a box cafion, a bog of volcanic ash and sphagnum was found.—W. J. G. Lanp, The University of Chicago. Fic. 1.—Ophioglossum: protocorm bearing sterile leaf. CURRENT LITERATURE MINOR NOTICES Trees and shrubs.—Part III of the second volume of this work has been issued,t and contains full and lucid descriptions of some 30 species, 25 of which are accompanied by carefully executed full-page illustrations, including detailed drawings of flowers and fruit. Nearly all of the plants considered are native in the South conneo and Gulf states, and about one-half of the species treated are new to science. New species are published in the following genera: Quercus (1), Hamamelis G) , Crataegus (3), Prunus (6), and Sambucus (1). The high standard of excellence, characteristic of the previous parts, is” fully maintained in the present issue.—J. M. GREENMAN. Flora of Congo.—A second fascicle? of the third volume of this work has appeared recently, which records the results of further studies in several fami- lies of spermatophytes from the Gramineae to the Compositae. A number of species new to science are included, described, and illustrated in the same excellent manner as in previous fascicles of this florai—J. M. GREENMAN. NOTES FOR STUDENTS Experiments with maize.—Several years ago BLARINGHEM’ published a monograph on his now well known experiments in the production of anomalies in various plants as the result of mutilation. The mutilations forced into development buds which ordinarily remain latent, and the branches produced from these buds frequently possessed characters not recognized as normal features of the plants operated on. In a small percentage of cases the abnor- malities thus brought to light were found to be inherited to a greater or less degree, and the conclusion was reached that mutilation is a very general and easy means of provoking mutability and an important factor in the evolution of vegetable forms. Most of his experiments were made with maize, thoug' some apparently corroboratory evidence was derived from barley (H. distichum and H. tetrastichum) and mustard (Sinapis alba). All of the new characters, abnormal or otherwise, which came to light in his experiments with ma aize * SARGENT, CHARLES SPRAGUE, Trees and shrubs. [Illustrations of new or little known ligneous plants, etc. 4to, pp. 117-190. pls. 151-175. Boston and New to Houghton Mifflin Co, IgrI. $5.00. D ILDEMAN, Emme, Flore “ Bas- et du Moyen Congo. Ann. Mus. Cane Belge. Bot. V. 3:149-316. pls. 28-49. 1910. Brussels. * BLarincuem, L., Mutation et traumatismes. Etude sur l’évolution des formes végétales. pp. 248. pis. 8. Paris: Felix Alcan. 1908. 480 Ig1t] CURRENT LITERATURE 481 were discovered in the descendants of one original plant mutilated by the author in r902. After that time the pedigrees were kept carefully controlled, either by hand-pollinations or by cultivation in isolated plots. The reviewer,‘ at about the time this monograph appeared, demonstrated the occurrence of numerous biotypes in hybrid combination in what appeared to be a fairly uniform population of maize, and believes this to be the general situation in this species. JOHANNSENS has pointed out that the reviewer's results favor a different interpretation of BLARINGHEM’s experiences, since the new types which proved to be hereditary may have appeared as the result of segregation of biotypes which were already present in the original plant chosen for mutilation, this segregation being due, not to the mutilation, but to subsequent method of breeding. GriFron* has given further support to this appear when no mutilations have been practiced, and the reviewer has had the same experience. GRIFFON shows that the abnormalities which character- ized BLARINGHEM’s forms are strongly dependent upon seasonal conditions for their devel t, being much more abundant in all cultures in some seasons and less abundant i in alti in other seasons. He does not agree with BLARING- HEM that with respect to these abnormalities these maize families constitute ever-sporting varieties. It does not follow, however, that abnormalities are not hereditary because they are strongly affected by the environment. Hus and Murpocx’ have shown the inheritance of fasciation in a strain of popcorn, the offspring of two fasciated ears giving progenies over 50 per cent of which produced fasciated ears, while an unfasciated ear from the same strain gave only 3 per cent fasciated ears. It will be understood, of course, that the strain from which these ears were selected was complexly hybrid, and that pure-bred derivatives might have shown either approximately 100 per cent fasciated or approximately no fasciation, under favorable conditions. There is evidence that the fasciation is strongly fluctuating, the two ears on a single stem being not infrequently one fasciated and the other normal. The significance of the percentage inheritance is doubtful in complex material of this kind The reviewer’ has presented additional evidence of the hybrid nature of ordinary vigorous maize plants, and their dependence for their vigor upon HULL, G. H., The composition of a field of maize. Report Am. Breeders’ Association 6. 1908. S JoHANNSEN, W., Elemente der exacten Erblichkeitslehre. pp, vi+-516. Jigs. 31. Jena: Gustav Fischer. 1909. ° Grirron, E., Observations et arg expérimentales sur la variation chez le mais. ae Soc: Bot. France 57:60 . 1910. 7 Hus, H., and Murpock, A. W., ce of fasciation in Zea Mays. Plant World 14:88-96. rorr. § SHULL, . H., a methods in corn breeding. Amer. Breeders’ Mag. 1:98—107. 19 482 BOTANICAL GAZETTE [DECEMBER this hybridity. Previous conclusions that F, hybrids between self-fertilized strains are on the average equal in yielding capacity, and in certain combina- tions much superior, to strains cross-bred in the normal manner, have been — confirmed; also that reciprocal crosses are essentially equal. In addition it is shown that the yield and quality of the crop are functions of the particular hybrid combination, the results being the same whenever the cross is repeated. The F, was found no more variable than the pure self-fertilized parental strains, but the F, was considerably more variable, the coefficients of variability in latter gives no coefficients, clearly demonstrates the segregation of different grades of such purely quantitative characters. East has also presented similar evidence of the segregation of a quantitative character (height of stalk) in the F,, but he makes no reference to the reviewer’s corresponding results published a year earlier. He gives no coefficient of variability for pure strains, but his coefficient for the F, was 8.68 per cent, while in the several F, families it ranged from 12.02 per cent to 15.75 per cent. eory that the increased vigor of cross-bred maize plants is due to a stimulation accompanying heterozygosis requires that crossing within the same biotype or within the same F, shall give no advantage over self-fertiliza- tion in the same biotype or in the same F,. The reviewer™ has reported on a number of such sib-crosses in comparison with corresponding self-fertiliza- tions, the advantage in favor of the crosses being so slight that they can be fdirly accounted for by the lack of complete genotypic purity in some of the self-fertilized families. Crosses between sibs in ten self-fertilized families had an average height of 20 dm. and gave an average yield per acre of 30. 17 bushels. as compared with a height of 19.28 dm. and a yield of 29.04 bushels in the offspring of self-fertilized parents. In the F, those families which sprang from sib-crosses in the F, had an average height of 23.30 dm. as compared with 23.55 dm. in families produced from self-fertilized parents, and the corresponding yields per acre were 47.46 and 41.77 bushels respectively. These results show that cross-fertilization is of no (or little) advantage except when it brings together unlike hereditary elements. The relations of F, and F, in regard to height of plants and yield per acre strikingly emphasize the economic importance of using hybridized seed corn. Ten F; families had an average height of 25 dm. and produced an average yield of 68.07 bushels, 9 Emerson, R. A., The inheritance of sizes and shapes in plants. Amer. Nat. 44:739-746. Igo. * East, E. M., The genotype hypothesis and hybridization. Amer. Nat. 45: 160-174. figs. 6. 1911 * SHULL, G. H., The genotypes of maize. Amer. Nat. 45:234-252. fig. I. 19tt- ’ 1911] CURRENT LITERATURE 483 while twenty corresponding F, families had an average height of 23.42 dm. and gave a yield of only 44.62 bushels per acre. Hayes and East have also shown a similar relation between first and second generation crosses, one such cross giving 105.5 bushels per acre in F, and only 51.5 bushels in F,, another cross giving respectively 117.5 bushels per acre and 98.4 bushels per acre. These authors give a good discussion of the economic bearings of these results and methods of putting them to practical ‘Cotzmss has also shown the practical value of hybridization methods in corn growing, reporting on the results of sixteen rather wide crosses, all but two of which gave higher yields than the average of the parents, and all but four exceeding the better parent in yielding capacity. PEARL and SURFACE,™ while subscribing to the correctness of the genotype idea as applied to 7 are of the opinion that the ordinary ear-to-the-row selection method “in a much cruder and less precise way, really makes use of the same chia the reviewer's “‘pure-line method,” and they wider simply the relaxation re) genotypes will have been satoinaticalty eliminated.” This view fails to t account of the relatively greater vigor in the F, hybrids. East, Hayes and East, and CoLins,” on the other hand, urge the use of the method of Morrow and Garpner,* as the most practical means of utilizing the greater vigor produced by heterozygosis, and the reviewer believes that the attitude of these authors is justifiable. The method of Morrow and GARDNER is identical with the “pure-line” method, except that highly developed commer- cial varieties are used in the place of pure self-fertilized strains. The two chosen parental types are grown in alternate rows in an isolated plot, and one variety is detasseled. The seed for the general crop is harvested from the detasseled row, and the process is repeated year after year, using the same parental varieties East and Haves” have made a most important contribution to knowledge ™ Hayes, H. K., and East, E. M., Improvement in corn. Bull. Conn. Agr. Exp. Sta. pp. 21. pls. 4. 191t. 3 Cottins, G. N., The value of first-generation hybridsin corn. Bull. rgr, B.P.L., U.S. Dept. Agr. pp. 45. 1910. ™% Peart, R., and SurFace, F. M., Experiments in breeding sweet corn. Ann. Rep. Maine Agr. Exp. Sta. 1910.. pp. 249-307. Bull. 183. jigs. 220-233. *5 East, ., The distinction between development and heredity in inbreeding. Amer. Nat. 43:173-181. 1909. 6 Op. cit. 17 Op. cit. *® Morrow, G. E., and GARDNER, F. D., Field experiments with corn 1892. Bull. 25, Ill. Agr. Exp. Sta. pp. 173-203. 1893. 9 East, E. M., and Hayes, H. K., Inheritance in maize. Bull. Conn. Agr. Exp. Sta. pp. 137. pls. 25. 1911. 484 BOTANICAL GAZETTE [DECEMBER of the inheritance of unit characters in maize, and have succeeded in clear- ing up most of the difficulties met by CorrENs and Lock, and simply by the expedient of applying a strictly individual analysis, instead of permitting pollinations from a number of individuals possessing the same characteristics. Only a few of the more striking results can be mentioned. There are two independent genes for yellow endosperm color, giving F, ratios 3:1 and 15:1. These are so related as respects dominance that the intensity of the yellow color agrees approximately with the actual number of Y genes present, i.e., the color is most intense in seeds having both genes homozygous, less intense when one gene is homozygous and the other heterozygous, still less intense when both are heterozygous or when either is absent and the other homozygous, etc. This situation results in a distribution of individuals in the form of the probable error curve, and is therefore superficially like that of fluctuating variations, from which it differs however in that the different grades are inherited. In another paper the senior author” makes use of these facts in extending Men- delian theory to include variation that is apparently continuous. In purple aleurone color, East and Hayes find no less than four independent genes involved in different varieties, a full purple color requiring the simulta- neous presence of both P and C, a full red color the presence of Rand C. In the absence of C, both P and R are capable of producing some pigment, giv- ing “particolored” seeds. In addition to these three genes, there was found in a cross between Tom Thumb pop corn and Black Mexican sweet corn, a factor which partially or wholly inhibited the production of the purple aleurone color. This inhibitor or “(dominant white” is strictly normal in its hereditary havior, and its presence in some of Lock’s strains undoubtedly accounts for that investigator’s aberrant results. In pericarp colors the authors sige nize five independent red-producing genes, R: the ordinary red of “red” maize, R, the striped red of “calico corn,” R; a dirty red most abundant at the base of the grains and apparently completely coupled with red silks, R, and R; a rose red which reaches full development only on exposure to the sunlight. The red cob-color is a simple Mendelian dominant, independent of pericarp color. While starchiness is an endosperm character and shows xenia, the quality of the starch, whether flinty or floury, is a “plant character,” and affects all the grains of an ear. Crosses between flint and dent varieties show undoubted segregation with the flint character recessive, but there are prob- ably several genes involved, and the results are obscured by physiological correlation. Further evidence is given that size characters, such as height of stalk, length of ear, and size of grains, segregate normally in the F2. Several abnormalities are mentioned, dwarfness, striped leaves, split and furrowed cobs, branched ears, and hermaphrodite flowers. With exception of the last, these characters are thought to be inherited in Mendelian fashion, though the * East, E. M., A Mendelian Se of variation that is apparently con- tinuous. Amer. Nat, 44:65-82. 1910. 1911] CURRENT LITERATURE 485 possibility is suggested that fasciation of the ears may bea purely physiological effect of disturbed nutrition. MERSON* reports the discovery of red aleurone color as a latent character in a cross between Queen’s Golden pop corn and Black Mexican sweet corn though other crosses between these two varieties gave only purple Slenrote: Crosses between a tested homozygous red-aleurone strain and White Rice pop corn and Evergreen sweet corn produced F,’s with only purple aleurone cells, thus demonstrating the presence of P as a latent character in both of these white varieties. Dark and light yellow endosperm colors were also seen to be latent as a result of a cross between the orange-colored Queen’s Golden and the Black Mexican with colorless endosperm. While not experimental, two papers by Itt1s” on abnormalities are worthy of mention. Both of these abnormalities are assumed to have been induced by the traumatic action of Ustilago Maydis. In the first the glumes of the female flowers were somewhat enlarged, and in place of the carpel arose a tubular structure 10-20 cm. long, terminated by a long pistil-like thread 20 cm. long. The occurrence of a ligule on this structure served to identify it as a phyllode, and leads the author to the conclusion that the ovary, which after- ward forms the seed coat, is homologous with the leaf sheath, and the style with the leaf blade. Within this tube, as a prolongation of the axis, grew an abnormal leafy branch. In the second paper?’ the author describes abnormal orescences in which the flowers are paired, each pair consisting of a sessile female or hermaphrodite flower and a stalked male flower. This is an arrange- ment characteristic of the Andropogoneae, and the author looks upon its appearance in maize as a reversion. On this basis he would rank the Zeae asa subtribe of the Andropogoneae, in support of Hacker and Stapr, who had adopted this arrangement on other grounds.—Gro. H. SHULL. ichen parasites.— ToBLER™ has studied the relation of two so-called lichen parasites to the lichen host, to the alga on which the lichen grows, and to the substratum to which the lichen is attached. After the manner of think- ing commonly followed by European botanists, and often by American as well, Emerson, R. A., Latent colors in corn. Ann. Rept. Amer. Breeders’ Ass. 6: 233-237. I9I0. 2 Intis, H., Ueber eine durch Maisbrand verursachte intracarpellare Prolifikation bei Zea Mays L. Sitzungsber. Akad. Wiss. Wien. Math.-naturw. Klasse 119. pp. 15. pls. 2. 1910. 43 Int1s, H., Ueber einige bei Zea Mays L. beobachtete Atavismen, ihre Verur- sachung durch den Maisbrand, Ustilago Maydis (DC.) Corda tiber die Stellung der Gattung Zea im System. Zeitschr. Abst. Vererb. 5: 38-57. pls. 2. Igtt. 24TostEer, F., Zur Biologie von Flechten und Flechtenpilzen. I. Ueber die bicuhenenn 4 sales Flechtenparasiten zum Substrat. Jahrb. Wiss. Bot. 49:389- 409. pl. 3. fig. I. 1911. 486 BOTANICAL GAZETTE [DECEMBER he considers the lichen to consist of the fungus and the alga on which it grows, instead of accepting the logical view, namely, that the fungus alone constitutes _ the lichen. Phacopsis vulpina Tul. and Karschia destructans Tobler, of the Pezizineae, are considered with respect to their biological relation to the lichens on which they grow and to the algal hosts of these lichens. Phacopsis vulpina is found on the thallus of Evernia vulpina (L.) Ach. in the Alps. By sectioning the fungus and the lichen host together in paraffin and subsequent treatment with iodine solution, the author was able to trace the course of the Phacopsis hyphae Phacopsis is best developed in the lichen thallus, the algae are entirely absent- In other portions of the lichen thallus the algae are surrounded singly or in groups by the Phacopsis hyphae, the Evernia hyphae being absent from such places. In other places the hyphae of both Phacopsis and Evernia are found entwining the algae. Thus it appears that the Phacopsis hyphae in time ‘reach the algae in limited areas of the lichen thallus and gradually displace the hyphae of the latter. It seems that the algae multiply more rapidly for a time after the Phacopsis hyphae reach them, but may finally disappear entirely where these hyphae are most abundantly developed. When the Phacopsis hyphae have reached the region of the lichen thallus where the algae are found, they spread laterally until large portions of the Evernia cortex are cut off from the medulla within and finally die. The Phacopsis hyphae are found to penetrate into the dead cortex and into the medulla of the Evernia. The foreign hyphae are absent from the spermagonia of the Evernia and areas immediately surrounding them, but are present in the soredia, which may serve as portals of entry. The conclusion is reached that the Phacopsis is probably first a parasymbiont and later a parasite on the lichen thallus Karschia destructans Tobler is described from the thallus of the lichen Chaenotheca chrysosephala (Turn.) Th. Fr. It was found that the Karschia penetrates into and through the crustose thallus of the Chaenotheca and into the bark upon which the lichen thalli examined grew. In growing through the lichen thallus, the Karschia is found to entwine and destroy algal cells and to displace and destroy the lichen hyphae. This makes the Karschia a parasymbiont with the lichen and likewise a parasite on it. But finally, the Karschia hyphae penetrate into the bark, after which ‘the fungus fructifies. So before the fungus produces its fruit, it becomes a saprophyte. Thus @ parasitic, a parasymbiotic, and a saprophytic condition are found in one ontogeny. The author reaches the conclusion that the Karschia is for a time a lichen-fungus (we would say a lichen), but at other times a parasite or 4 saprophyte. Whether this fungus is a lichen is really a matter of definition ; but whether a given plant should be called a lichen or not is of no speci biological importance. If its relationship with the alga is accompanied by no morphological characters which should separate it from the genus Karschia, 1g11] CURRENT LITERATURE 487 the fungus must remain in that genus. Several other species of Karschia are numbered among about 400 fungi that grow on lichen thalli, and a study of each of these would be of special interest and value. The author states that his study of these two fungi proves that there can be no sharp separation of the many fungi known to grow on lichens into para- sites, parasymbionts, and saprophytes, since a single species may show all three conditions at various times in its life history. He thinks that further studies would demonstrate that most of the fungi found growing on lichens are not purely parasitic, but parasymbiotic and often saprophytic as well. In this he is probably correct, and further research along this line would add much to our knowledge of the biological relations of these fungi. The c con- demarkation between lichens and other fungi. This is true, but a consider- able number of botanists have already concluded that the oa distinction between lichens and other fungi should not serve longer to maintain the lichens as a distinct group in any general classification of plants. Some other fungi growing on lichens were examined briefly, without add- ing materially to the important results secured in the study of the two species considered above.—Bruce FINK. Evolution of vascular structures.—In a bulky memoir of 325 pages, CHAU- VEAUD*® expounds his view of the evolution of vascular bundles as they are found in different groups of plants. He finds himself in disagreement with the current notion of the stele as a morphological concept of first importance, and returns to the earlier view of a vascular bundle as the unit. With him, in fact, a vascular bundle is either a xylem or a phloem group, and these are arranged according to one of six “dispositions”: (1) centric, corresponding to protostele; (2) excentric, with the xylem group more or less flattened; (3) alternate, represented by a root with diarch structure; (4) intermediate, as seen in the hypocotyl of some plants; (5) su , a circular row of co- lateral bundles; and (6) peripheral, FE by amiphivasal bundles such as are seen in monocotyledonous stems. Thus what most writers call a pro- tostele is by CHAUVEAUD, as well as earlier writers, regarded as the most primitive condition; the alternate arrangement of xylem and phloem exhibited by all roots is the next main step in evolution; and from this root structure are to be derived the conditions seen in the stems of gymnosperms and angio- sperms. It will be seen that this mode of derivation lays a heavy responsi- bility on the hypocotyl, for this transitional region is considered to reveal the stages in evolution leading to the stem structure of all the higher plants. One must swear entire allegiance to the recapitulation theory when adopting this scheme, although certain difficulties appear, for instance, in connection 2s CHAUVEAUD, G., L’appareil conducteur des aon vasculaires e principales de son évolution. Ann. Sci. Nat. Bot. IX. 13: 113-438. rig or) Igtl. 488 BOTANICAL GAZETTE [DECEMBER with the origin of amphivasal bundles. To some it may appear an unneces- sarily round-about plan to derive a circle of collateral bundles from a proto- stele via the root, when direct routes have been proposed which do not violate the doctrine of recapitulation. Moreover, it would be interesting to see how the stele of Osmunda could be derived according to the new method, inasmuch as in ferns the evolution is said (p. 271) not to proceed further than the third or alternate disposition The memoir is divided into doe parts, in the first of which a fairly com- plete historical résumé is given. This is rendered more valuable by the group- ing of the papers under six headings. It is to be regretted that a number of errors have crept into the citations. The second part is devoted to a sum- mary of the author’s earlier researches in this field; while the third part con- tains an account of his new observations, extending over a wide range of vascular plants, including a large number of dicotyledons, though the criti- cally important cases found in his group ‘‘vascular cryptogams”’ are repre- sented only by Pieris cretica—-M. A. CHRYSLER. Fermentation.—Experiments of HarpEN and Norris*® confirm the work of other investigators according to whom many yeasts which ordinarily do not ferment galactose acquire the property of fermenting that sugar by being cultivated for a time on a medium containing it. The authors further show that the juice from such a yeast is also capable of fermenting galactose, and that the addition of phosphates to the fermentation-mixture causes an acceleration of fermentation similar to that observed in mixtures of glucose, ructose, or mannose and yeast juice on the addition of phosphates. As in the case of these hexoses, the phosphate is in the form of an organic compound from which it is not precipitated by magnesium citrate mixture. Small quantities of sodium arsenite also accelerated fermentation. Regarding the constitution of the compound formed when a phosphate is added to a fermenting mixture of yeast juice and a hexose, three views have been proposed. According to HARDEN and Younc it is a hexose-phosphate containing two phosphoric acid residues. LEBEDEW holds that the compound contains only one phosphoric acid residue, basing his view on the fact that the ozazone obtained from it has only a single phosphoric acid residue. The third view is that of IwaNorr, who considers the compound a triose phosphate. In a recent paper, purely chemical in its content, but of great biological inter- est in so far as it clears up part of the mechanism of fermentation of sugars by yeast juice, Younc* presents further evidence to show that the compound is * EN, A., and Norris, R. V., The fermentation of galactose by yeast and yeast juice (Preliminary communication). Proc. Roy. Soc. London B 82:645-649- Igto. 7 YounG, W. J., Ueber die Zusammensetzung der durch Hefepresssaft gebildeten Hexosephosphorsiure. II. Biochem. Zeitschr. 32:177-188. 1911. 1911] CURRENT LITERATURE 489 a hexose phosphate containing two phosphoric acid residues. The evidence is based largely on the composition of the barium salt of the compound, an on the behavior of its ozazones. In the formation of the ozazone, a single phosphoric acid molecule is split off, while the ozazone also contains a phos- phoric acid residue. It has been known that yeasts are able to ferment a number of substances other than sugars. The number of such substances which undergo a kind of fermentation accompanied by the evolution of carbon dioxide has been greatly extended by NEUBERG and Tir.* The substances which are fermented in this way by yeasts and yeast preparations are the common plant acids which occur naturally in fruit juices and other substances used in alcohol production, and also components or products of the yeast cell, as fatty acids, glycerine, and lecithin —H. HassELBRING. Soil productiveness indicated by natural vegetation.—The practical object of SHANTz’s Bulletin? on “Natural vegetation as an indicator of the capabilities of land for crop production in the Great Plains area”’ does not detract from its scientific value. It is an interesting and valuable example of the application of exact ecological research methods, with results establishing reliable data relating to the natural vegetation of a given region, and its corre- lation with the crop-producing capabilities of the land. Detailed investiga- tions were made in Washington and Yuma Counties, Eastern Colorado, al- though a general survey included all the states of the Great Plains, a region containing the largest body of land of possible agricultural importance in the United States on which the native plant cover still exists. The methods included study of the vegetation with respect to the formations, dominant associations, and important species, and of the various determining factors with especial consideration of the physical conditions (temperature, rainfall, evapora - tion, saturation deficit, soil moisture, soil temperature, etc.). Records for these physical factors were made at 11 different stations on the Great Plains, under direction of Briccs, and supplemented by SHANTz with many compara- tive observations. For purposes of comparison, the soil moisture determina- tions were reduced to definite standards, as moisture equivalent and non- available moisture (for Kubanka wheat). Plant migrations, invasions, effects of fire, grazing, mowing, and other biotic agencies are considered. Illustrations of the root systems of significant species are given and their relations to the soils and in the successions are noted. Indicative of agricultural land are the grama-buffalo grass and the wire grass 28 NEUBERG, C., and Tir, L., Ueber zuckerfreie Hefegdrungen. II. Biochem. Zeitschr. 32:323-331. IQII. - 99 Santz, H. L., Natural vegetation as an indicator of the capabilities of land for crop production in the Great Plains area. Bur. Pl. Ind. Bull. no. 201. pp. 100. S. 6. figs. 23. IQII. 490 BOTANICAL GAZETTE [DECEMBER associations (both short grasses), also bunch grass and sand hills mixed (prairie grasses). Each of these types is characterized as to general appearance, floristic composition, correlated physical factors, effects of disturbing factors, variations from the typical association. e relationships and successions of the different associations are outlined, primary and secondary successions being recognized, though these do not appear to be fundamentally distinct. he remainder of the bulletin is concerned with crop production in the light of the data obtained, with practical suggestions as to the choice of land and to methods of culture.—LauRA GANO. Embryo sac of Pandanus.—In 1908, CAMPBELL published a preliminary note on the embryo sac of Pandanus, and in 1909 a fuller paper appeared. Now a third paper has appeared," based upon material that shows the com- pleted structures of the sac. Three species are included (P. Artocarpus, P. odoratissimus, and P. coronatus), so that the results may be regarded as fairly representative of the genus. e primary sporogenous cell (overlaid by several layers of parietal cells) divides into a large inner cell and a smaller outer one, the latter dividing again. e embryo sac is developed by the innermost cell, which thus represents two megaspores. The usual divisions occur to the 4-nucleate stage (a pair of nuclei at each pole of the sac). The micropylar pair divides, and there is organized a normal egg apparatus and its attendant polar nucleus. Before this occurs, however, the two antipodal nuclei initiate a series of free nuclear divisions, accompanied later by wall-formation, until finally 64 or more antip- odal cells may be formed before fertilization occurs. A variable number of antipodal nuclei are free and fuse with the micropylar polar nucleus to form a single large endosperm nucleus, or two such endosperm nuclei may be formed by the multiple fusions. In the formation of endosperm by the usual stages of free nuclear division, wall-formation, and centripetal growth, the author states at the “endosperm nuclei diminish in size as division proceeds, and this dimi- nution in size is accompanied by a corresponding reduction in the number of chromosomes,” although no count seems to have been made. The excessive amount of antipodal tissue preceding fertilization certainly suggests that the antipodal cells are to be regarded as representing the vege- tative tissue of the gametophyte, and so far as this feature is concerned, it seems safe to assume that it is primitive. In the organization of the egg- apparatus, however, it is not so much a question of the number of cells in the sac at the time of fertilization, as the number of divisions between the mega- spore nucleus and the egg. In this case, since two megaspore nuclei are in- volved, there are just two successive divisions between a megaspore nucleus and the egg derived from it, instead of the usual three divisions.—J. M. C. %® Bot. Gaz. 47:485. 1900. * CaMPBELL, D. H., The embryo sac of Pandanus. Ann. Botany 25:773-789- bls. 59, 60. figs.-2. 1911. 1911] CURRENT LITERATURE 4g1 Physiological behavior of Hypocrea rufa.—MepIscu® has made a physi- ological study dealing mainly with the factors influencing the production of pigment by Hypocrea rufa, and the behavior of the fungus toward ammonium salts, nitrates, and nitrites as sources of nitrogen. The conidia of this fungus are green when grown on alkaline media, while in acid media yellow conidia are produced. When the fungus is grown in liquid media containing only glucose, the pigment diffuses into the medium, while the mycelium remains colorless. The medium passes through shades varying from green to yellow, orange, and brown. Certain salts, as the chlorides of magnesium, sodium, and potassium, potassium chlorate, and magnesium sulphate, have a specific stimulating effect on the production of pigment. This stimulation is limited for all these salts to isotonic solutions varying from 0.05 to 0.125 gram-molecules per liter. No pigment is produced in the presence of ammonium salts of strong acids, owing to the accumulation of free acid. The pigment production is regarded as an oxidation process, as it takes place only in the presence of oxygen, and the colored solution can be decolorized by reducing substances like sodium sul- phite, hydrogen peroxid, and sodium hydrogen sulphide. The addition of an excess of calcium carbonate, infusorial earth, kaolin, and similar substances, decreases the intensity of color, probably as a result of absorption. fungus grows with either ammonium salts, nitrates, or nitrites as a source of nitrogen. Nitrates are reduced to nitrites. With ammonium salts of strong acids, growth is soon depressed, and the formation of conidia is inhibited. As the fungus has no invertase, it cannot use cane sugar; however, in the presence of ammonium salts cane sugar serves as a source of carbon, owing to its inversion by the liberated acid. When nitrites are given as the source of nitrogen, conidia are produced only in the light, except when levulose is present. In that case, a few conidia are produced also in the dark. Ammonium salts are utilized in preference to nitrates, and ammonium salts of organic acids in preference to those of stronger mineral acids. Experiments to determine if the fungus assimilates free nitrogen did not give definite results. The paper contains a great number of data on the interaction of various substances in nutrient media in which fungi are growing. —H. HASSELBRING. Peroxidase and respiratory chromogens.—A number of experiments to test the various methods of preparing peroxidase have been performed by PALLADINE and IRAKLIONOFF,%} who find that the best method with tissues containing small quantities of proteins, as watermelon, pumpkin, etc., is to extract with water or 10 per cent NaCl, and precipitate the proteins with saturated aqueous HgCl. The enzyme is then precipitated from the purified filtrate with 95 per cent alcohol. The best solvent of the precipitated enzyme # Mepiscu, Marc, Beitrige zur Physiologie der Hypocrea rufa (Pers.). Jahrb. Wiss. Bot. 48:591-631. Igt0. 33 PALLADINE, W., and IraKLionorr, P., La peroxydase et les giao respira- toires chez les ientea Rev. Gén. Botanique 23:225-247. 1911 492 BOTANICAL GAZETTE [DECEMBER is K,HPO,. From their experiments they further conclude that peroxidase occurs in some plants as enzyme, in others as zymogen, and that the quantity present in different plants varies considerably. The smallest quantity in any of the plants studied was found in Aspergillus niger and the Saccharomycetes. A suggestion is made in this connection which is very important if true. Th think it probable that yeasts are capable of producing alcoholic fermentation even in the presence of free oxygen because they contain very little or no oxidiz- ing enzymes. The experimental evidence for this view is too slender as yet to be considered seriously; but if it proves to be true, it will clear up the relation of fermentation to the respiratory process. The quantitative distribution of peroxidase and the respiratory chromogens shows a direct correlation, tissues rich in peroxidase containing much of the chromogens, and vice versa. Moreover, the tissues of plants are found to con- tain substances which are conceived to “stimulate” the color reactions used in detecting peroxidase. The products of alcoholic fermentation, which are rich in oxidizable substances, are placed among these stimulators of the forma- tion of respiratory pigments. Finally, boiling of aqueous extracts containing chromogens is believed to render the formation of pigments impossible, either by changing profoundly the chemical nature of the chromogens, or by destroy- ing the substances which stimulate the formation of the respiratory pigments which are produced by the action of such substances as emulsine and peroxidase on the chromogens. Most of the conclusions and suggestions seem to rest on a minimum of experimental evidence—Cnar es A. SHULL. The flora of Newfoundland.—The report of a botanical expedition to Newfoundland by FERNALD includes the mention of many additions to the flora of the island, which is now known to possess 783 indigenous species. An inquiry into their geographical origin shows that about 60 per cent are boreal, including 28 per cent common to southern Labrador and eastern Canada. An additional 3.5 per cent are Canadian types not found in Labrador. A surprisingly large number of species are southwestern types found also in Nova Scotia, New Brunswick, and coastal New England, but unknown or rare in Quebec and Ontario. This class contains 274 species, or 35 per cent of the Newfoundland flora. At present 16 endemic plants are known, com- gus 2 per cent of the flora, o explain the abundance of plants identical with those of the Atlantic seaboard south of Newfoundland, the writer postulates the former existence of a bridge formed by an elevated coastal plain, composed of siliceous soils, connecting the island with Cape Breton and forming an ideal highway for the northeastward advance of plants which thrive on such soil. This siliceous bridge, according to the writer, would have been highly unattractive to such 34 FERNALD, M. i A bot cone | p qty: 4.5 “wT. ¢ 31. 3 and southern Labra= dor. Rhodora 13:109-162. r9r1. Tg11| CURRENT LITERATURE 493 species as Adiantum pedatum, Thuja occidentalis, Lilium canadense, Calypso bulbosa, Lonicera canadensis, Solidago squarrosa, Aster macrophyllus, and many other similar plants not found in Newfoundland, and which in eastern Canada “scrupulously avoid the more sterile areas.” This explanation and the considerable lists of “calciphiles” indicate that the writer believes the vegetation to respond directly to the chemical character of the substratum.— Gro. D. FULLER. Root tubercles of cycads.—Three papers on root tubercles of cycads, recording conflicting opinions, lay emphasis upon different features of these rather well known structures. ZACHSS pays particular attention to the fungus hyphae, which branch profusely and become coiled together, after which the coils become digested. The fungus infests the tissues, causing the abnormal development, and the cell reacts by absorbing the fungus, a phenomenon which reminds the author of phagocytosis in animals. The relation is not symbiosis, but parasitism. HokejS1° comes to the conclusion that the relation is symbiosis, and that the alga is the only cause of the abnormalities in the roots, the fungi and bac- teria being merely the accompaniments of degeneration. The alga enters by the lenticels. The third paper, by Miss Sprart,3? deals entirely with the life history of the alga, and gives a much more detailed account than has hitherto been avail- able. She finds that the heterocysts are reproductive bodies, the contents of which break up into gonidia capable of reproducing the filament, as described Branp for Nostoc. The central body is described as a simple structure, incapable of anything but direct division. No reference is made to the work of OLIVE, whose technic and figures might have been helpf None of the three writers refer to the work of Lrre,* who described the mode of entrance of the alga and the general development of the root tubercle. —CHARLES J. CHAMBERLAIN. Cretaceous flora of Japan.—SuzvuxK1 has described two conifers from the Upper Cretaceous of Japan as new. One of them is made the basis of a new genus (A biocaulis), and is said to be nearest to Abies among living forms; 35 Zac, FRANz, Studie tiber Phagocytose in den Wurzelkndllchen der Cycadeen. Oesterr. Bot. Zeit. 60:49-55. pls. 2. 1910. 36 Horesyst, J., Einiges tiber die symbiontische Alga in den Wurzeln von Cycas revoluta. Bull. Intern. Acad. Sci. Bohéme 15:1-10. figs. 24. 1910. 37 Spratt, ETHEL Rose, Some great on the life history of Anabaena Cyca- deae. Ann. Botany 25:369-380. pi. 32. I9II. 38 Bor. Gaz. 31: 265-271. 1901. 39 Suzux1, Y., On the structure and affinities of two new conifers and a new fungus from the Une Cyetacooun of Hokkaido (Yezo), Bot. Mag. Tokyo 24:181-196. pl. 7. 1910. 404 BOTANICAL GAZETTE [DECEMBER the other is a new species of Cryptomeriopsis, the generic name suggesting the reputed affinity. A new fungus is also described, parasitic on the shoots of Cryptomeriopsis, and is referred to the Pyrenomycetes as a new genus (Pleo- Sporites Fuyne has followed Suzuxt’s paper with a short discussion of the features of the cretaceous flora of Japan so far as uncovered, and especially contrast- ing it with the results of HoLtick and JEFFREY in the United States. He announces a change of opinion as to the affinities of Yezostrobus and Yezonia (Stopes and Fuji 1910), being convinced now that this strobilus and stem, whether they belong together or not, are to be associated with the araucarians. The discussion of the causes of extinction is preliminary and suggestive rather then definite, attention being called to the influence of such factors as para- sitic fungi, injurious gases from volcanoes, climatic changes, “(inherent char- acters,” etc. Even the cytological situation is included, the fluctuating num- bers of chromosomes in angiosperms and their fixed number in gymnosperms suggesting a relation to the variability and hence adaptability of the former group, and the fixity and decadence of the latter group.—J. M. C. An ecologist’s ak botanical garden of a new type, situated on Mount Aigoual, a peak of the Cevennes, and due largely to the foresight and energy of Professor FLAHAULT, has recently been described by SKENE.* The situation seems almost ideal for the study of many ecological problems, as it lies between the Atlantic and Mediterranean basins, with an elevation that permits the mesophytic vegetation of the former to thrive within a few miles of the xerophytic plants of the latter region. The presence and proximity of calcareous, siliceous, and granitic soils add to the value of the region for experimental purposes. In addition to the garden proper (800 feet below the summit), there is a at at the very top of the mountain, and a bog which forms the source of a strea Since the ‘ecidius of the garden (known as “L’Hort de Dieu”’) in 1903, a laboratory capable of sheltering a dozen people has been erected, and several — thousand seedling trees and shrubs have been planted. Trees from all parts ‘of the earth are being grown, in order to find those most suitable for forestry es in southern France, and to solve such ecological problems as the factors which limit tree species at certain altitudes. Not only the garden but the entire mountain is being made one gigantic ecological experimental plot.— Gero. D. FULLER Leaves of Calamites.—Tuomas* has undertaken an investigation of the leaves of certain species of Calamites, to obtain from their structure indications # Fujyu, K., Some remarks on the cretaceous fossil flora and the causes of extinc- tion. Bot. Max Tokyo 24:197-220. 1910. 4 SKENE, Redeerereee An ecologist’s garden. New Phytol. 10:64-68. 1911. ” THO H. Hamsuaw, On the leaves of Calamites (CALAMOCLADUS section). Phil. Trane Roy: Soc. Landon B 202:51-92. pls. 3-5. 1911. 1911] CURRENT LITERATURE 495 of their environment. In short, it is a study of the ecological anatomy of fossil leaves. The leaves of Calamites are mostly known as impressions, and Tuomas has referred the structures he has been able to obtain to the better known impression forms. The petrified material used was obtained from the Lower Coal-measures (Halifax Hard Bed), and five types of leaf were distin- guished. The twigs bearing the leaves proved to be quite interesting in stelar structure, especially in its relation to that of young stems of Equisetum. The ecological conclusion is as follows: ‘The leafy twigs seem to have grown in a pendulous fashion, and the structure of the mesophyll and epidermis suggests that the habitat was a damp one. On the other hand, the leaves possess some xeromorphic features, such as the presence of fibers in the longer forms. The evidence points to a marsh or swamp forest as their habitat; this may Sali been near the sates but if so the soil probably contained little salt.”—J. M Transpiration in salt marsh plants.—Transpiration rates of cut shoots of Salicornia annua and Suaeda maritima have been found by DELF* to be equal to or greater than those from equal surface areas of such mesophtyes as Vicia Faba. The highest degree of succulence seemed to be accompanied by the highest transpiration rate per unit area. Relating transpiration to evaporation from a water surface, unit areas of Salicornia lost 32 per cent and of Vicia 26 per cent as much water as equal areas of water surface. It was shown that : Salicornia is able to absorb water readily through the surface of its stems when submerged, and less convincingly that it does not absorb sufficiently through its root system to replace the loss by transpiration except in a humid atmos- phere. This seems the more surprising, since TRANSEAU* has shown evapora- tion to be exceptionally high in salt marshes. The stomata in Salicornia and Aster trifolium appear to have distinct powers of movement in young plants early in the season, losing this plasticity at a later date——Gro. D. ULLER Cytology of the ascus.—An account of the cytology of Helvella crispa Fries is given by Miss CarruTuers.s The cells of the hypothecium are one to several-nucleate, and some of the nuclei were observed to fuse in pairs, but no migration was observed like that in Humaria. An attempt was made to deter- mine the number of chromosomes on the spindles in the vegetative hyphae. Apparently two chromosomes are present in the vegetative spindles, and four or eight on the spindles in the fertile hyphae, but owing to the minuteness of the objects not much importance can be attached to these observations. The 43 Deir, E. Marion, Transpiration and behavior of stomata in halophytes. Ann. Botany 25:484—505. Igtt. 4 Bor. Gaz. 45:217-231. 1908. 45 CARRUTHERS, D., Contributions to the cytology of Helvella crispa Fries. Ann. Botany 25:243-252. ais. 2. 168%, 496 BOTANICAL GAZETTE [DECEMBER divisions in the ascus follow the same routine as described by Miss FRASER in Humaria rutilans. The first mitosis is heterotypic, the second homotypic, and the third brachymeiotic, leading to a reduction without division in the last mitosis. The spores are formed by the astral rays in the manner described by Harper for Pyronema.—H. HassELBRING. A parasitic orchid.—According to the investigation of Kusano,“ the vege- tative body of the orchid Castrodia elata consists of a tuberous rhizome which multiplies through the production of tuberous offshoots. If these offshoots form no mycorhiza, they decrease in size and finally die without being able to flower, but if infected by the mycelium of Armillaria mellea they enlarge, flower, and produce daughter tubercles; it is therefore concluded that the orchid is completely parasitic upon the fungus. The mycorhiza is of the ecto- tropic type; occasionally, however, the fungus behaves as a parasite, pene- trating deeply into the tissue of the tubers and causing their collapse in a manner similar to that seen in potato tubers attacked by the same organism.— EO. D. FULLER. Budding in Cycas.—While in Japan, Miss Stopes*7 noted the origin of the well known adventitious buds of Cycas revoluta. They arise on the upper portions of old leaf bases, some appearing more than 200 crowns back of the growing point. None were found arising from the axis, and the young buds do not seem to have any connection with the axis. The buds when removed grow into normal plants, but when they develop strongly upon the parent plant they give rise to the so-called “branching,” and in such cases, of course, vascular connections are established with the main axis.— CHARLES J. CHAMBERLAIN Kusano, S., Preliminary note on Gastrodia elata and its mycorhiza. Ann. Botany 25:521-523. IgIt. 47 Stopes, Marte C., Adventitious budding and branching in Cycas revolute. New Phytol. 9: 234-241. figs. 7. 1910. GENERAL INDEX Classified entries will be found under Contributors and Reviews. New names and names of new genera, species, and varieties are € printed i in bold face type; syno- nyms in zéalic. A Abies —— oe, ering of 36 Adinobotrys 4 oe cet ey Africa, flora Ve After-ripening, i in as 306 Agaric Alcohol, hydrating with 63 Alectori Pees New 2 Zealand 4 ine e 408 on of generations in Ascomy- é a Senpeialee of 407 panty O., work of 406 Anaerobic growth 243 Anemia nipeénsis 407 ier ence endosperm of 380 Antennaria 408 Apgar, -, “Ornamental shrubs” 405 Apogamy, i in ferns 166; in Pellaea 400 Appleman, Appleton ene Primers 235 Aquilegia 1 Arber, E. . Newell, “Plant So alpine Switze rlan Se 236; work of 234 ork he hecho: eaeutatus 163 Ascocarp of Lachnea scutellata 275 gray dip alteration of pol Ree hace © cytology ology of 24 i 495 reas , flora of 9 Astrothalamus Atmosphere, at =o of 126 Australia, flora o Axonopus 407 B Bailey, I. W., work of 327 Beer, Rudolf, gyre - 244 Benedict, H. "M. 2 B enedict, B.C. a of 406 Bensley, R. R.; ce of 167 Bertholletia 2 26 Besleria pycnosurzygi. Be ve opew. “Plant tite of Maryland” Bethel, E., work of 407 Bicknell, E., Ww Blaringhem, L., work of 4 epee, PH. Plant life of Maryland” J Sines , J- C., work o : ‘olivin’ mosses of or Pipe from 407 , A., work of riquet, John, “Flore Care O07 rooks, W. E. St. J., work of 242 rown, Nellie A, work of 75, 238 rown os aversion: in Cycas Buellia mexicana foie Burns, — P. 105 : urret, M., work of 408 J suscalioni i jock of 407 Cc os ium a 45 mbridge se - Ca mpanulari Campbell, D. He work of 328, 490 Cardot, J., = ork of 1 arduus vern aricoideae, Philippine 409 , D., work of 495 astilleja austromonta _ — ecidology 236; pro woe vs 3 edar in Ohio 416 PE EOOOS EE a Central Ameri ica, 45 497 498 Ceratozamia, adult trunk of 81 ee mberlain, Charles J. 73, 81, 163, 164, 165, 167, 168, 244, 248, 319, 322, 323, 324, 326, 328, 405, 406, 493, 490; work of 324 poms - igs of 407 Cha Chauveaud G., work of 487 a ee work of 407 isten wi Chromogens, peroxidase and 4 s, of Dahlia gee va Ginkgo ; usr, 487; ‘Plant life of hasan nd” 4 Cirsium Greene Rot: Clarkia, elegans 267; parviflora 267; rhomboidea 2673 Sige Pg 267 lintonia, embryo sac of 209 te, W. N., w es of 161 oastal floras 77 kayne ba Pana Zealand plants” 159 oelarthri olacodasy: ollins, G. N. "ork of 483 ollomia grandiflora axillaris 270 onifers, layering among 369 onnarace pecory “temperature apparatus, elec- _~ €itae> 209 oS 0 — _~ Cantiberes: Appleman, C. O. 306; Ben- edict, H. M. 232; Brown, W. H. 275 439; Burns, G. P. 105; erlain, Cc. 73, 81, 163, 164, 165, 167, 168 See a. Cook, Mel T. 236, 386, 410; W.S. 360; Coulter, J. M. 67 es ee 234, 324, 326, 380, 406, a6 49°, 493, 494; Cowles, H. C. Crocker, W. 67, 79, 241, 243, 245, 247, 340, 423, 427, 308; Da chnowski, A. 1, 126; Fink, brace ar: Fuller, G.D: 80, 159, 193, “ae 247, 248, 321, 325, 328, 405, 41 2, , 6; Gano, Laura 404, 3805 “Ch og wt 246,415; Greenm an, J. M 406, 480; Hague, Stella M. - ’ Has- I, Hem A. F. 15 4903 way, . eiffer, Norma E. 166; Pritchard, F ms 169; Robinson, B. L. INDEX TO VOLUME LII [DECEMBER schleger ; WwW. Cook, Mel. T. 236, fae Cooper, W. S. 369 Copeland, E. E work of 161 7, 158, 160, 234, 324, Coupin, e, a cikeate des Cryptogames” Cone, rt C. 4c2 Coxella 4 Craib, W. oe work of 161 Craiba Cranberry apa vegetation of 1, 126 Cycad, adult t cank ey 8 budding in 496; root tuberles fo) Cyrtophora Cytology of cacus 495 D : Dachnowski, Alfred 1, 126; work of 416 Dahlia chromosomes 0 32 Davenport, “Domesticated animals and plants” 233 Davis, B. M., work of 60, De Candolle, C. enters of i, , 497 d Ol 495 Denizot, Georges, work of 41 Desert plants, pear relations of 79 ee pcamag re aa DeWildemai, “Emile, (Flore du Congo” Digitalis, inheritance in 78 Dioon, adult trunk of 81 Diospyros ateienk morphological a, proteol of 3 26 Drude, O., ecetcon der * Erde ’ 402 19it] Drymonia 407 Dunn, S. T., work of 407 E East, E. M., work of 413, ape , 483, 484 Ponies: units of Miho oy Edgerton, C. Elatostematoides 163 Elm . D. E., work of 1 Poko Dioepyros. 395 Pseudtars 416 Embryo sac, 209; Diospyros . A., wor Endosperm, snispeataik a —— Bagley A. A,, he. cteanices der Erde” 402; 9 Seadoo i sac of 439 Erigonum ochroleucum 262; ovalifolium ovalifolium celsum 262; ovali- i 262; vineum 262 cere sacs of 164 and plant succession 193; and vegetation 1 Ewart, A. J., pec of 408 ¥ Fairman, C. E., work of 408 Felt, E. P., work of 238 Ferdina ndsen, re work of 408 ion 488 new spe in 1615.0 uth peice as 161; cultures of prothallia 166 F ertilization, of Diospyros 37 icus 4 oe Bru in Florideae e, Fomes, subendothejus 407; surinamensis Posi plants 158 Fraser, H. C. fy ., work of 2 Free Rob. E., work of eg 408 of 328 ia 163 Fujii, Ke ark of 404 Fuller, Geo. D. 80, 159, 193, 23 247, 248, nes 3255 328, 405, 410, 492, 494, 495, 496 INDEX TO VOLUME LII 499 Fungi, new species of 408; Russian 163; . Texas 161 G pepe eas Ag: Sete 416 Gano, Lau 5 plant names Ginkgo, chromosomes - 328 Gleason, H. A. 2 . Re ee ‘work of 235 , 160, ror, 406, 480 Gymnosporangium Kernianum 407 H ne sg Stella M Hall, ., and isons Har, 408 Basbereet: J. W., work of 325 Harter, L. L., wi ork of 40 paste Hasselbring, H. 75, 155, 239, 245, 246, 316, 320, 43, 488, 491, 496 Hassler, E., . of 161, 4 Hauya 48; lucida 48; - “6 quercetorum 7 ruacop Hayes, H. K., ei of = 3, 483 Heald, F. D., "work of 1 Hedges, Florence, work oF 239, 408 Heilbronn, Alfred, work of 166 Helgoland, temperate plants in 246 Heller, A. A., work of 16 nsel F. 153 Hemsley, H. B., work pai se Hepaticae in Scotland 3 500 Herbst, P., work of 238 Heredity, in oats 318; theories of 323 Heterochromosomes 323 eydri : 79 Home University Jeary 234 2 tera Honcamp, ie , work of 246 ° Howe, R. H., Jr., work of 409 Huron River Valley, botanical survey of 105 Hus, H., work of 4 Hybri idiza fern 166 ides / Risea rufa, ier a akaice of i ed SO South American 163 I vg new cana oe 261 tis, H., work o intesine siedinis. ta brittle or woody feet | in Digitalis 78 © be 409 lows “ties peat bogs i ran, - aed ot 491 Irrigato Ishi see M., work of 326, 328 cea Re ba flora o H. Mike ocaphie des ea der auf Java” 67 Javenese woods, micrography of 67 Johannsen, We ork of 481 Jones, W. N., ork of 78 Judd, John W. ak of 234 K Keeble, F., work we ay 234, 318 pany work of 4 tis Kuwada, ri, work of 322 Laboratory air Lachnea sculelats. ascocarp of 275 INDEX TO VOLUME LII [DECEMBER Lan »,W. J. G. 391, 478 Layering a conifers 369 Leaf-fall 8 pals - Citas 404 Lechmere, A. F., work of 240 Lee, E., pala fe) "80 Leeuwen-Reijnvaan, J. and W. Docters von, work of 2 Lehman, Ernst, work of 2 Laciniaria scariosa 409 W sianthus meianthus qui 1; quichensis 51 thospermum stots olatum 372; ruderale anceolatum 2 iverworts, peer in a vhdcpids of 320 Loheria 162 pcg te dry! work of 323 unell, J., wor! Leaping sI 161; nen 161; sabulosus Lychnis, reversible sex-mutants in 329 MacDougal, D. T. 2 McFadden, M. E. ror of 162 bri i. work of 162 work of 240, 242, 413, 414 Maize, experiments in ate Mamillaria Maryland, oni life of 404 Maslen, A. J., work of 326 Massee, George, " Diseases of cultivated plants and trees” 155 Mayepea 409 a blag work of 491 Memor Mendelism 2 235 rrill, E. D , work of 162 rritt, 7 L. work of 162 Merritt; tia Mesoxylon, schon’ of 326 Michigan peat bogs 105 ayi, Kiichi, ak of 416 Mitosis in Spinaci Modilewski, J., wreak fe 164, 165 torr] Modry, bead work of 411 Molliardia Monardella savebralia be haute ve 25% Morrow, G work of 4 Moss, ae E., work of 321 Mosses, Bolivian 163; Mexican 161; of work of 324 Murdock, A. W., work of 481 Murrill, W. A., rk of 162, 409 Myxotheca 4 08 N Nabokich, A. J., work of 2 Nasturtium side pee Toalisiee 264; Naturhiches Pflaisgen faciiliies Navesink Highlands, vegetation ce 325 Nawaschin, Sergius, work of 1 Neljubow ms Th wate eae 27 Nelson: Aven 261 Neuberg, C., wor Newbigin, Marion I., work of 234 A ios rate fi 402 New Zealand, algae of ie _— 159 Nidularia, morphology © Nienbur , Wilhelm, wo ae 247 Nieuwland, J. A., work of 247, 409 Nilsson-Ehle, H., work of 318 Fs N = te rage — vegetation of 325 oe ie of sr North “American. Flor Nor , work oe 238 Nuclei ‘syndiploid 248 Oats, inhibiting factor in 318 Oenothera, gene etic studies in 68 ac ©, ae of 411 ridez 269; um palmat me fertile ke of siidecsha © ef 478 : Opsianthes gaurioides 267 Opuntia 161, Orchid, a new 400; jabs nl 496; Boe th Am ers Sees mn meethy los: Overholts, L. O., wor rk of 409 Overton, j. B. 242 as gh rie seacaiaticns of Xanthium seeds Palladine, W., work of 491 Palmer, Edward 61 INDEX TO VOLUME Lil 501 Pammel, L. ri _ of 248 Pasanth mosse! achat pane sac of 328, 490 Paniceae 407 Panicate 409 Paraguay, Leguminosae pee Convolvu- laceae of 408; plants of 1 Parasitism, analysis of 249 od in Taraxacum 167 Pentstemon cera 272; perpulcher 273; 8 Permeabilit eroxidase fe chromogens 491 etals, ig of 3 7 *hacelia luteopurpurea 27 -*haeostoma — 267; perviior 267; rhomboidea 267; xanthiana hilippine Caricohdeae 409; oni 161; orchids 4 Piperaceae 161; plants 161; er 162; Urticaceae 162, Sisal ieee’ fedek heed be wy ww 409 Phlox aculeata saiomiomerscigy e ate plants 241 Phycomycetes 23 Phyllocactus Fichlamii 163 Physostegia, emb mee 218 Phytomyxaceae 413 eye Oey a new gree 158 Pierce, Newt gee work of 1 Piper, ’Bolivia Piperacene, Philippine 161 Pitt Pit sn, a a 32 es Plant and a eding Plant Sageetin sage gr iin aad ucpeation 193. Polygonums, phe ibious 247 Polypodium prolo ic we 161 Pol Polytaenium quadriseriatum 407 Potato, after-ripening of 306 265 Primula, hereditary factors in 317 Pritchard, F. J. 169 502 Proteolytic enzyme of Drosera 326 Pr eee water cultures of 166 4 Prunus geniculata 408; padifolia 265 ini Puccinia gra yearly origin and dis- semination of 16 Punnett, R. C., ““Mendelism” 235 urp | wor rk of Pseudolatix, “gametophytes and embryo of 4 R Ray, John, — of 248 Rees, Bertha Renner, O. geod of = 3 Reproduction, hea Rev Ap rennet Shrubs” ] ildeman’s u Congo” 480; Engler and Drude’s “Vegetation der Erde” 402; and plants” 2 33 0 Urban’s ‘Symbolae tillanae’’ 160; hmer’s “Planzenstoffe”’ 67; Wett- stein’s “Handbuch” 405 inotrichum 16, ork of 162 Root tubercles ot reads — san ee Ps alustris 263; palustris 264; a. terrestris globosa ae wis hispida 264 Rose, J. N., wor 160 , R. C., work of 327 Rosenstock, E., work of 162 pea 407, 4 usby, H. H. oe of 409 ries fungi 163 Rydberg, P. oe work of 162 INDEX TO VOLUME LII [DECEMBER Safford, W. E. 61 Sandbergia 2a Santaloides Sage and ae gall 324 par Pegi © Sz, brees — shrubs” 480 Saunders, Miss E. re ork of 78 Scalia, C., work of 4 Reheleabecs, G., oak of 162 chindler, A.K., work of 162 Schlechter, R., Schmaltzia pubescens I : Schneider, C. eo Handbuch der Laub- holzku series Schenella 1 Schroeder, i, Pi of 79 Scirpus Lon, Scotland, Hepaticae of i Scott ork of 2 Scutachne Seaver, F. ae ark of 162 Seeds, germination of Xanthium and alle minimum 453; longevity of Setchell, W. A., work of 162 Seward, AC 4 “Fossil Layee 158 Sex, dawnt or eame maioukn in Lychnis dioica Gerashity of Ascomycetes 298 Shantz, H wi Shull, C. wy 325, 326, 453, 4 Shull, Geo. H. 68, 78, = ne 318, 329 0; work - 48r, ss flora o Si icydium m Tuerekheim 49 Simarubopsi Skene, Maceresor, wget of 494 Small, — ork of 1 Smith, A Me ork fee sar E. oe pokes of 157, 238, 324) Smith, John Donnell 45 Smith, Ra 2, os — of 157 Smit Wilso Smut spores, feed: co oni aining 246 Soil productiveness and natural vegeta-. Ig1t] abla ge implexa 267 el R., work fee 403 Squamolithon 42 409 Standley, P. C., babe of 409 , and Hall, J. G., “Dis- of o. plants” 155 Stilbochalara eo. Fc work © 60 Sympetalae, of Amazon 407; Philippine ey Tabernaemontana Deanii 50 s micola eh 3 m, L., work of 1 q ‘pe ule ne E., ob of 407 Tir, L., work of 489 é ri , G., work of 1 ‘Tison, Adrien, work ae i 413, 414 Tobler, F., work of 485 Tore a 407 a piven d, C. O., work of 75, 238 Transeau, Edgar N. Transpiration, —_ ratus for study 54; and light intensity 417; physics 322; 95 re salt marsh plants 4 INDEX TO VOLUME LII Za Z Zeijlstra, H. H., work of 7 Zimmermann, 593 ES oe responses 322 r, A., work of 237, 238, 412 Tuberc Fici 408 247 Tecllemtints 407 U Units of vegetation 321 U: ; 160; im hes mbolae Antillanae”’ wor of x Urticaceae, Philippine 409 V Vite aes of 167 Valot Vaucdat: structure, evolution of 487 Viola 161 Vittarieae 407 Wachter, W., work of 2 Wehmer, C., "“Pflanzenstofie” 67 eidel, F., work 0 236 ve d TS 5 Woo Woronichin Wallechions, W. A. 6 ¥ et Kono, work of 4 Young, W. z. 226; eek “ 488 Z ch, Franz, work of 493 ult trun ., work of 246 # Clean, Dustless Floors are essential to the health of the children under your care. Dust is the fecatcat carrier and distributor of disease germs known, and the constant stir in schoolrooms is apt to keep dust circulating in the air in dangerous quantities. Standard Floor Dressing is ee only effective remedy for the dust evil. Standard Floor Dressing holds down all dust and germs as soon as they settle on the floor. It prevents their further circulation in the air, and removes one of the most frequent causes of contagion. Standard Floor Dressing also preserves the floors and keeps them from splintering and warping. It reduces the abor and cost of cleaning, and thus pays for itself Spies times over. Write for free book- let on dust dangers ow to avoid ional aera ear me ae th t ~ : = ae ate Not intended for household use. Standard Oil Company Uncorporated | It’s Baker's It’s Delicious Made by a perfect me- chanical process from high grade cocoa beans, sci-~ finest quality, full agek and absolutely pure and healthful. Sold in 1/5 e. Bat Ib., 1/2 Ib. and 1 Ib. , net we ight. Booklet of Chait Recipes Sent Free ER BAKER & CO. LID. Established 1780 DORCHESTER, MASS, Hygienic Heating 4 Stay of 65 © 3 degrees F. with a am st: humidity of 60 per c s much mor mfort ng healthful eae oe when st teapleat are is higher and the air dry n furnaces the water-box i Ad ‘be petal filled and a little Platt’s Chlorides added t ith steam heat, hot water paper Baltimore heaters, Ses oil, or gas stoves, ish w water containing a little Platt’ $ * onpaides shoul ek oe ver or under the heating arrangemen The Odoriess Disinfectant. A colorless liquid; powerful, safe, l, and e ical. Instantly destroys foul odors ae chemically Montreal : Platt’s Chlorides | | have been established over 60 YEA By | PIANOS 222s are ee oe change sous in your home free of expense. Write for C Cabiieae aoe D and ¥oOSe & SONS PIANO co piano. We