CARDED 19a4 Rae ow 2 ai 2 ra ©. Dwicht Marsh. iu t WISCONSIN GEO OLOGICAL AND NATURAL HISTORY SURVEY. E. A. BIRGE, Ph.D. Sc.D., Director. BULLETIN NO. XII. SCIENTIFIC SERIES NO. 3. THE PLANKTON INVERTEBRATE OF Crustaces Lake Winnebago and Green Lake BY C. DwicHt Marsu — . Professor of Biology in Ripon pe ae sees gahisbaht: bed ti PAS ". fi a 2 5 on “ae a (s NOV a 1933 Sapa ZEAL RAR ni uss et MADISON, WIS. PUBLISHED BY THE STATE. October, 1903. vim Wisconsin Geological and Watural History Survey. BOARD OF COMMISSIONERS. RoBpert M. LAFouuETTE, Governor of the State. CHARLES R. VAN Hisz, President, President of the University of Wisconsin. CHARLES P. Cary, Vice-President, State Superintendent of Public Instruction. CALVERT SPENSLEY, President of the Commissioners of Fisheries. JOHN J. Davis, Secretary, President of the Wisconsin Academy of Sciences, Arts, and Letters. STAFF OF THE SURVEY. E. A. BirGez, Director of the Survey. S. WEIDMAN, Geologist. Survey of Central and Northern Wisconsin. U. S. GRANT, Geologist. Survey of Southwestern Wisconsin. N. M. FENNEMAN, Geologist. Physical Geography of Lake Region. C. D. Marsa, Biologist. Biology of Lakes. L. S. SmitrH, Civil Engineer. Survey of Lakes and Rivers. W. D. Suita, Field Assistant. E. T. HANcOcKE, Field Assistant. Consulting Geologist. T. C. CHAMBERLIN, Pleistocene Geology. ‘eae Iw V., CONTENTS. Page POAT Le OM DELNIE: OB) STUDY o/c siclere\s Sie ovclsivieie cis seis! tievele cise alesse: nies . 1-10 Lake Winnebago and Green Lake...............cc cee eeee ees 1 Methods of making collections................ 2000-002 seee cee 8 Cuapter II. Annuat DisTRIBUTION OF THE ORGANISMS OF THE PUES OUING Sd oreo eeaitnte eectta ev chete sates aie tel aCe ay Manone oe ato 11-46 Distribution of C. brevispinosus and C. pulchellus in Wiscon- SUI AK OBI Wie ea sels & Sigs gies wei ave verses seve le Ricslel Maule atali Talia lorena auc heab eae 27 PREP esc LO OTT 6A are cies al clcvm alate w/c: atstesdthel ah ic eate Yate aiic ae ahs nveten Seetale ch orate 36 Annual distribution of the total plankton ...............eeeeee 38 Constituents which produce piankton maxima................ 39 Comparison of amount of plankton in different years.......... 41 Comparison of plankton in Green lake and Lake Winnebago.. 42 Comparison with the plankton of other lakes.. ................ 43 SHABEnBe LE) DISCUSSION OF RESULTS) of 500)) 5 0.55 aleatdeles wai oeiee 47-59 alae otsplaniztony Collectionsica cs acuecs cis ecneice i creiors Wheels cists sist 47 Relative importance of plankton constituents in producing REE AVENE AS Se Siete cits sralee\eveleneee gale eS TR GIS cele ahs RRR SMG Sea Ne 49 Comparison of plankton and temperature curves.............. 49 Comparison of curves of total plankton with curves of plankton MCUMUMEULO LUGS pererevsetsiese bevoveyavic erature lavelevetety Sreve soak avelev ere iter apotenereretetieus 51 PMSA EA LSE UR UID LOR 3) 5/010) e/e.s)'v)sicyeg oie device o eine isieieieneie a's; s 26 al eieeie 51 Comparison of plankton collections over muddy and stony bot- BOOTUNSS erepete rene rare tay of cfake cok cveyaue ve aie caucvoytolicreverolinleraremura csoncietemiionstoiereletotens 59 CHAPTER TY. DisTRIBUTION OF SPECIES ........cccs ccc ence ences 60-69 SPRL AB MCU CIS TELOUUDION x cs cicis: «eielc civ cles svsic.e'c 4 siecesieleipe aioe 60 Comparison of the faunae and florae of different classes of Oe Sera Acton SES eRe Ee eee a aha thom rateava wera ietiec dye tans Uhtadoauate 62 Comparison of plankton of successive years........ 0... eee eens 65 Relative value of deep and shallow lakes for the production of REM NE MGE MONAE Bs Ue lat aig wua'a subie hai eiaiieieled sieve mata-cl Gidwicrsis 67 iv CONTENTS. Page APPENDIX. (STATISTICAL, GABIEHSs 3)... eiyene arc unit nial ua aie 73 Table I. Total volumes of plankton per square meter in Green DW Oh rs ike ko ties oe cic ie a Malti ise UCR eiciay St gaa et 73 Table II. Total volumes of plankton per square meter in Lake WNME DAO s.3% eaten atresia tty Eames Uae ae ea . 74 Table III. Total volumes of plankton per square meter in va- MlOus Wisconsin lakes ye Siey ia Aeon yale Fhe ee 75 Table IV. Numbers of D. minutus and D. sicilis per square MMO LOAM GECCMM AOL) fe ence Vesec cua ten sus APA arctan mt ep geireteteg 77 Table V. Numbers: of D. Hae per square meter in Lake Winnebago.. Ss 78 Table VI. Numbers of Ez. Inonetiie t per laauare enue: in anes Winnebago ......... 78 Table Vil. Numbers of E. Hone aan einen ae in neha LEY CN PSR annie Gi ic bh SPM Ret ae IM nea tug: Sar nuOUnaS ATR A Amani cH 79 Table VIII. Numbers of ZL. macrurus per square meter in Greemilalei aac yu ses sects te caer shnsest a Wed AUG Sie tt com cae ae mae 79 Table IX. Numbers of C. brevispinosus per square meter in Dake Wine bar ols ei wore Sonal ssa sae use ee Nae aa 80 Table X. Numbers of C. puichellus per square meter in Lake Wannebagoy ia cect a oe ious sso canary esas cl aa eee 80 Table XI. Numbers of C. lewckarté per square meter in Lake WITT COAG Oye nis ayer ale tereancicis Se sinic ic uaretave ce arelanrarerctalrate a teaeaier ps 81 Table XII. Numbers of C. prasinus per square sate 3 in Green ela Key ick ita cy. isis tele iitale atatelarelocerate estore eniene ie anlar 81 Table XIII. Numbers of copepod larvae per square meter in alk ou\Wir ne ago cies separ oe eles vicioteis eters oe eaenetaeest tale oe 82 Table XIV. Numbers of copepod larvae per square meter in Greenilakeuiiei enn ee nccuieve sce niclna eas yestanetaiate sielant eres 82 Table XV. Nos. of Diaphanosoma brachyurum per square meterin Make: Winnebago: jo). osu sss. cele owe asco see ecoe cee 83 Table XVI. Numbers of D. hyalina per square meter in Lake NAN AW OVE) ove Vena tara Mana ert Brch Ml enon oie AUN AI AD es a Mntel ald 6 5483 Table XVII. Numbers of D. hyalina per square meter in Green lake ciaie. omacudiaerecrcierelel scouusierseslevale esos actetoc laste aerate 84 Table XVIII. Numbers of Bosmina per square meter in Green lake wees Soe Oe een MS URe Ca acs mits ayaa ites cana geentinge 84 Table XIX. Numbers of Hurycercus lamellatus per square meteruins Lake Winnebacoeajaece see eniee eee 85 Table XX. Numbers of Chydorus per square meter in Lake AVE alae) of: Veto) ee roc Cis SoS Nis ON CENT A MMe aUSton TE, pS RRMA ie 85 Table XXI. Numbers of Leptodora per square meter in Lake Winnie aac oa eee si eh nce a ar ua a ev cee eval ena a 86 Table XXII. Numbers of Cypris per square meter in Lake IWIN OAL OMe) Me iocidaicieavaietckevatie oye unter aera ahatiel slate hepesalveicte pene renee t ae 86 Table XXIII. Maximum depth of Wisconsin lakes............ 87 PLATE if II. LE: Ve V. Walp XVI. ILLUSTRATIONS. Curves of annual distribution of Gloiotrichia per square meter in Lake Winnebago : 6 Curves of annual distribution of Diaptomus sicilis and Diaptomus minutus per square meter in Green lake . Curves of annual distribution of Diaptomus oregonensis per square meter in Lake Winnebago ; Curves of annual distribution of Hpischura laeuaires per square meter in Lake Winnebago Curves of annual distribution of Hpischura Dechistres per square meter in Green lake 6 : Ourves of annual distributioa of ennecuiaeus macru- rus per square meter in Green lake : . 5 Curves of annual distribution of Cyclops brevispinosus per square meter in Lake Winnebago : : : ; Curves of fannual distribution of Cyclops ae per square meter in Green lake Curves of annual distribution of Cyclops inunenelies per square meter in Lake Winnebago - j Curves of annual distribution of Cyclops heucean per square meter in Green lake and Lake Winnebago Curves of annual distribution of Cyclops prasinus per Square meter in Green lake j - : : Curves of annual distribution of copepod larvae per square meter in Green lake Curves of annual distribution of sonennd eas per square meter in Lake Winnebago : ; Curves of annual distribution of Din phan saree bra- chyurum per square meter in Lake Winnebago Curves of annual distribution of Daphnia hyalina per square meter in Green lake Curves of annual distribution of Daphnia hajedine ane D. retrocurva per square meter in Lake Winebago PAGE vi PLATE XVII. XVIII. XIX. XX. XX: XXII. ILLUSTRATIONS. Curves of annual distribution of Bosmina per square me- ter in Green lake ; ; : : ; 5 : ; Curves of annual distribution of Hurycercus lamellatus per square meter in Lake Winnebago ; Curves of annual distribution of Chydorus sphuericus per square meter in Lake Winnebagu . : 5 Curves of annual distribution of Leptodora hyalina per square meter in Lake Winnebago . . . . . Curves of annual distribution of total plankton in Lake Winnebago per square meter ; Curves of annual distribution of total Blanton in Gas lake per square meter PAGE 33 34 35 36 38 38 THE PLANKTON OF LAKE WINNEBAGO AND GREEN LAKE. CHAPTER I. OUTLINE OF STUDY. The attempt in this investigation has been to make a com- parative study of the plankton of two lakes of different types, with a collateral study of such other lakes as could be easily reached. It was thought that if, after a somewhat careful preliminary study, the plankton of the two lakes could be kept under observa- tion for a considerable period of time, many facts in regard to the annual and geographical distribution of the animals and plants could be secured, and perhaps some generalizations could be reached in regard to the principles controlling such distribu- tion. LAKE WINNEBAGO AND GREEN LAKE. Lake Winnebago was chosen for the type of the shallow lake mainly because of its importance from the standpoint of the pro- duction of fish. It is known to be an enormously productive body of water, and the fishing industry has employed a great many men in Oshkosh. Netting has been forbidden by legisla- tive enactment for several years, and, in spite of many infrac- tions of thelaw, it is generally acknowledged among all but inter- ested parties, that the number of fish has greatly increased in 9 PLANKTON OF WINNEBAGO AND GREEN LAKES. that time. There is now hardly a better lake in the state for fishing for sport for some kinds of fish. The perch are espe- cially large and handsome, and the black bass are numerous and gamy, although rarely exceeding three or four pounds in weight. Pike, too, are caught in large numbers, and white bass are abun- dant in the spring. | Lake Winnebago is some 28 miles long by 10 or 12 broad in its greatest width. There has never been an accurate hydro- graphic survey of the lake, but it is probable that it is nowhere over about 25 feet in depth. It is evident to a superficial ob- server that the plant life during the summer is very large, and it has been assumed that the abundant production of fish is correlated with the plant growth. The principal inlet of the lake, the Fox river, enters it about midway of the western shore, and leaves it as its outlet, at the northern end. Thus the lake may be considered simply as an expansion of the river. Connected with the Fox and its principal tributary the Wolf, is a number of lakes and streams which receive the drainage of a large section ot the northeastern part of Wisconsin, extend- ing from the southern boundaries of Marquette, Green Lake, and Fond du Lac counties to the southern parts of Forest and Oneida counties. Many of these lakes are merely expansions of the rivers, and although covering areas of considerable size, are for the most part very shallow. Lake Buttes des Morts, Lake Winneconne, Lake Poygan, and Lake Puckaway are the most prominent of these lakes; their shores are for the most part low and swampy, and their depth rarely exceeds 10 or 15 feet. There are a few deeper lakes in this drainage area: Stone lake is between 75 and 80 feet in its greatest depth; the Waupaca lakes, though small in area, are in some cases from 60 to 95 feet in depth, and Green lake, with a maximum depth of 287 feet, is the deepest lake in the state. The deep lakes, as would be expected, are more distinetly cut off from the other parts of the drainage area than the shallow lakes. In the case of the shallow lakes, many open one into the other so that there is no distinct line of separation between OUTLINE OF STUDY. 3 them. It would be expected that this separation of the deeper lakes would have some effect on the character of their fauna and flora, besides the effect produced by the difference in envir- onment. The east shore of Lake Winnebago is, for the most part, high, and in some places rocky. At the south end the shore is swampy,—in fact it is rather difficult to distinguish between lake and shore. At this end the Fond du Lac river flows in, and there is a gradual encroachment of the shore line upon the lake. The west shore of the lake is low, but not, to any con- siderable extent, swampy, and is gradually being dotted over with summer cottages. At the north end of the lake are exten- sive sand beaches. The material of the lake shores is glacial drift, so that everywhere the shores are lined with boulders washed out of the drift by the waves. The bottom of the lake is generally composed of a fine mud filled with organic matter. In many cases, however, a bottom of boulders extends quite a distance from shore. Off Stony Beach this rocky bottom extended perhaps a half a mile from shore, and then is succeeded by a mud bottom without any dis- tinct change in depth. In other cases the bottom near shore is eomposed of sand or red clay. Before this work was undertaken, very little was definitely known of the plankton of Lake Winnebago. Only occasional collections had been made. It seemed necessary therefore to make a continuous series of collections lasting over a consider- able period in order to get a basis of comparison. It was neces- sary, too, that there should be an opportunity to examine the living collections, as many things are sure to be overlooked in preserved material. Accordingly a summer station was established at Stony Beach, a small summer resort about two miles south of Osh- kosh. Comfortable quarters were found in an old hotel build- ing, the dining room being fitted up as a laboratory. The laboratory equipment and a working library were brought from Ripon College. A row boat was provided for the regular daily work, and, through the kindness of Mr. Chas. Schreiber of Osh- 4 PLANKTON OF WINNEBAGO AND GREEN LAKES. kosh, we had the use of a sail boat for longer trips. Through the courtesy of Mr. M. W. Peck and Mr. D. Jack of Fond du ™ Lac, we were provided with transportation in their gasoline yacht for an extended trip through Lakes Buttes des Morts, Winneconne, and Poygan. Acknowledgment should be ren- dered, too, for unnumbered services rendered by Mr. D. O. Fernandez of Oshkosh. The location proved to be particularly convenient, as Stony Beach is reached by an electric line from Oshkosh and yet is so far removed from the city that under ordinary conditions it is not probable that this part of the lake is contaminated by the city sewage. Systematic work on Lake Winnebago was commenced the fifth of July, 1899. During July and August, with the excep- tion of a few days spent on other lakes, daily plankton collec- tions were made at at least two locations. For these daily col- lections a station was selected about a mile from the shore on the muddy bottom common to all the deeper parts of the lake, and another nearer shore en the rocky bottom. This was with a two-fold object, first to have two stations some distance apart in order to get an average of planktcn, and second to determine whether there was any decided difference in the plankton over the mud and over the rocky bottom, for the fishermen think that some fish have a decided preference for the stony bottom. Some days a considerable number of collections was made, the locations being widely distributed over the lake. During the summer the collections extended over a distance of some twelve or fourteen miles on the west shore of the lake; many were made in the central region of the lake, and some on the east shore. A number of collections, for comparison, were made on other lakes synchronously with those on Lake Winnebago, my assist- ant remaining on that lake while I did the work at other loca- tions. After the month of August the collections were kept up at intervals of about two weeks, the collections being made ordinarily at the two regular summer stations off Stony Beach. MARSH OOLLECTION”’ OUTLINE OF STUDY. 5 These collections were continued through a period of two years and a half. Collections at a similar interval of two weeks were also made on Green lake. Green lake was selected for comparative work, partly because of its convenient location, but mainly because its conditions are so different from those of Lake Winnebago. Green lake is situated in Green Lake county, about 25 miles west of the southern end of Lake Winnebago. It is about 734 miles long, with a maximum width of 2 miles. Nearly the whole lake is over a hundred feet in depth, and the western part has a maximum depth of 237 feet. The shore slopes are, for the most part, very abrupt, only a small part of the shore being swampy. The waters of Green lake are exceedingly clear, rarely being markedly discolored by vegetable growths, while in Lake Winnebago during most of the year the water is much dis- eolored. On account of the small depth of Lake Winnebago, storms disturb its water to the very bottom over most of its area, while in the depths of Green lake there is a large body of water which is never appreciably affected even by the severest storms. Because of its depth Green lake has a distinct ‘‘thermocline’’ during the summer months, and the water at the bottom has an annual range of temperature of only about ten degrees Fahren- heit. Lake Winnebago, on the other hand, has, during the sum- mer, a nearly uniform temperature from top to bottom. Lake Winnebago, because of its slight depth, and the fact that the whole body of water is so easily affected by storms, becomes warmed much earlier in the spring than does Green lake, and cools off with corresponding rapidity in the fall. The result is that Lake Winnebago is covered with a thick coat of ice long before Green lake is frozen over. Green lake is seldom covered with ice before the first of January, and parts of the lake sometimes remain open through the whole winter. As a result of the late freezing, the ice never reaches the thickness on Green lake that it does on Lake Win- nebago. Because of its great depth, and the consequent exist- ence of a thermocline in Green lake in summer, this body of water has a true “abyssal” fauna, organisms which can exist 6 PLANKTON OF WINNEBAGO AND GREEN LAKES. only in the peculiar environment of uniform low temperature and little or no light. Lake Winnebago, on the other hand, can- not be said to have an abyssal fauna, the animals of the bottom in the deeper parts of the lake not differing appreciably from those of the littoral region. ; With such differences in physical conditions we should ex- pect corresponding differences in fauna and flora. The writer has already suggested in a former publication (Marsh ’97, 181) that lakes may be divided into the two classes of “deep” and “shallow,” the dividing line between the two classes being at about forty meters. Later (Marsh, 99, 171) I was led to think that the limit should be placed at a lower figure,—per- haps thirty or thirty-five meters. It would be better, doubt- less, to make the main classification of lakes depend upon the existence or non-existence of a thermocline. In the shallow Jakes there is no thermocline. Taking the presence or absence of a thermocline as the basis of classification, the depth hmit between deep and shallow lakes would not be definite but would bear a constant relation to the area and character of the shore; for the thermocline is much more marked in small lakes with high shores. Deep lakes are susceptible of a two-fold classification into the large and the small. In the small deep lakes the abysssal water stagnates, and the conditions of life become so hard that an abyssal fauna can hardly be said to exist. In the large deep lakes, on the other hand, the movement of the surface waters under the influence of the winds produces slow return currents along the bottom which serve to relieve the condition of stagna- tion, and permit the existence of a somewhat abundant abyssal fauna. Green lake and Lake Geneva have the characteristics of large deep lakes, while Elkhart and the Waupaca lakes are types of small deep lakes. On the whole this seems to me the most satisfactory classi- fication of lakes, and in this paper I shall use the terms “deep,” “shallow,” “large deep,” and “small deep,” as indicated above. While, as will be seen later, faunal and floral distinctions do WISCONSIN GOL. AND NAT. HIst. SURVEY. BULLETIN No. XII, Puate I. JULY AUG. SEPT. OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE 500 - 450 ____. 1899-1900 1900-1901 400 350 300 250 200 150 100 50 Curves of annual distribution of Gloiotrichia per square meter in Lake Winnebago, the numbers being reckoned in thousands. ata OUTLINE OF STUDY. Vi not follow absolutely this classification, yet they have a close relation to it. Green lake may be considered the typical deep lake of Wis- consin, and, as observations have been carried on upon its fauna and flora for a number of years, it was natural to select it for comparison with Lake Winnebago. Collections were made on as large a number of lakes in other localities as time would permit. Some of these lakes were se- lected because they had apparently different conditions from those prevailing on Lake Winnebago and Green lake, but others were taken for the express reason that their conditions seemed to resemble very closely those of the lakes which were made the standards of work. Inasmuch, as will be shown later, experience has shown that plankton collections are really significant only as averages can be obtained of a considerable number of collections, and that single collections may be very misleading, so far as possible an attempt was made to visit a certain number of lakes repeatedly, rather than to make a large number of single collections from difierent bodies of water. Unfortunately the time at command did not permit of as many of these trips as was desirable, so that in some cases single collections only could be made: as it was important that there should be as wide a basis of com- parison as possible, it seemed better to make these single collections than no collections at all. The author clearly recog- nizes, however, that it would have been much better had it been possible to work a circuit of a considerable number of lakes continuously. If lakes could be classified into a series of a few types, of course, it would be necessary only to take one of each type. But, so far, no entirely satisfactory classifica- tion, from the standpoint of the fauna and flora, has been pro- posed, so that one can not be certain when he limits his work to a few lakes, that he may not miss some important principles of distribution which are only exemplified in the bodies of water which he has not examined. Four somewhat extended trips, in four successive years, were made to lakes in the forest region of Wisconsin, including lakes 8 PLANKTON OF WINNEBAGO AND GREEN LAKES. in Shawano, Forest, Oneida, and Langlade counties. The first of these trips was made in September, the last three in the mid- dle of August. To some of these lakes visits were made at other times. Such collections, as intimated before, while giv- ing a very imperfect idea of the faunal and floral conditions of these bodies of water, are yet very valuable as a matter of com- parison. In this work the objects kept in view have been the following: 1st. Lists of the fauna and flora. Inasmuch as the work has been done entirely by one person, with the aid of an as- sistant for a part of the time, and my exact systematic knowl- edge is very largely confined to the entomostraca, it is not to be expected that this list will be complete. It will, however, serve to show such important differences as may exist between the fauna and flora of Lake Winnebago, Green lake, and the other lakes. 2nd. A quantitative study of the plankton which should give a clear idea of the annual variations, and of the quantita- tive difference between the plankton of Lake Winnebago and Green lake. 3rd. ey irew Hit iad fp 3) | [ aed § a he _ S \ im of Etter Hi ae nee if ‘haf iy LA tll Ww ball Ay Se ee PAA Lees Mie A$ % i ‘ rage On 14 PLANKTON OF WINNEBAGO AND GREEN LAKES. lar fall growth, and that other growths may occur at irregular intervals as the wind happens to stir up the water; that the two most important conditions for the growth of the diatoms are a sufficient supply of nitrates and a free circulation of air, and that beth these conditions are found at those periods of the year when the water is in circulation. Whipple gives facts in re gard to the annual distribution of diatoms in Massachusetts ponds which seem thoroughly to substantiate his contention. I have already referred to this work in a former paper (Marsh °99), accepting these conclusions. In lecking over the occur- rence of the diatoms in Green lake and Lake Winnebago I find nothing to contradict this theory in the occurrence of Cyclo- tella, Melosira, Synedra, Fragilaria, or Stephanodiscus. The occurrence of C'yclotella in Lake Winnebago especially seems to confirm his statements. The oceurrence of Asterionella in Green lake, however, dif- fers distinctly from his results in Massachusetts waters. His general conclusion in regard to Asterionella is that its two max- imum periods come after the spring and fall overturning when the spores,—if diatoms have spores,—are brought to the sur- face accompanied by the food materials that have been forming in the abyssal waters during the stagnation period. Now in Green lake the maxima, as found in three winters, came in the depth of winter when the lake was covered with eighteen inches or more of ice, and at a period midway between the two overturnings of the water. It is evident that Whipple’s ex- planation does not apply in this case. Why there should be this enormous production of Asterionella in mid-winter I do not at all understand. Voigt (Voigt 702) reports Asterionella as having a similar winter maximum in Trammer-See and Ede- berg-See. Clostervwm. Two or three species of Clostertum occur in both lakes as occasional members of the plankton. They cannot be considered as true limnetic species, but rather as migrants from the littoral flora. ANNUAL DISTRIBUTION OF THE ORGANISMS. 15 Pedwastrum. I have found Pediastrwm in Lake Winnebago in every month of the year except March and April. It is most abundant in the summer and fall months but seems to have no pronounced maximum. Staurastrum. Staurastrum is found in Lake Winnebago from May to No- vember but never in any considerable numbers. Hudorina. Hudorina I have found in small numbers in June and July. ILerismopedia. Merismopedia was found in small numbers through the sum- mer and fall of 1899 in Lake Winnebago. In 1900 it was found only in the fall months, continuing to the middle of Feb- ruary. In 1901, too, it did not appear until fall except in a single collection in June. Clathrocystis aeruginosa Henfr. I have never found Clathrocystis in the plankton of Green Lake. In Lake Winnebago it occurs throughout the summer, appearing as early as June, and sometimes remaining as late as October. I have found it in great numbers in Lake Buttes des Morts in August. It appears in the same month in Peli- can lake and the Eagle River lakes. It does not appear to be a constituent of the plankton in the deeper lakes. Anabaena. Anabaena is one of the most important constituents of the summer plankton. It occurs in Green lake, sometimes in noticeable amount, so that little ridges of it are thrown upon the shore by the waves. It is in the shallow lakes, however, that it flourishes in especial abundance. It appears in Lake Winnebago as early as May, and may be found as late as Octo- 16 PLANKTON OF WINNEBAGO AND GREEN LAKES. ber. It reaches its greatest abundance in July and August. The numbers in September are ordinarily very small. Yet I have found it in Pelican lake in great numbers in the latter part of September. A phanizomenon. Aphanizomenon occurs in Lake Winnebago associated with Anabaena, its period of growth being very similar although it does not appear so early nor remain so long. While I have not counted Anabaena and Aphanizomenon, and so cannot state their maximum period with any exactness, I get the impression that Anabaena reaches its maximum earlier than A phanizom- enon. It is found in other shallow lakes associated with Ana- baena. Oscillaria. Oscillarva is not a constituent of the plankton in either Green lake or Lake Winnebago. In some of the shallow lakes, how- ever, it is very abundant at certain times in the summer. ‘This is notably so in Shawano lake where it seems to assume the importance that Anabaena and Aphanizomenon do in Lake Winnebago. Inngbya. LTingbya is associated with Anabaena and Aphanizomenon in Lake Winnebago, especially in July, sometimes in large numbers, but is of less importance than the other two genera. \ } Gloiotrichia echinulata Richt. Glototrichia has no importance in the plankton of Green lake. In Lake Winnebago it is found in great numbers in July and August. In the summer of 1899 (Plate I) there was a rapid increase from the first of July to the middle, fol- lowed by a decrease, from which there was again a rise to a maximum about the twelfth of August. In 1900 there was a single maximum early in July. The total production of Gloiotrichia in 1899 was much greater than in 1900. ANNUAL DISTRIBUTION OF THE ORGANISMS. fey The collections of Gloiotrichia in the other lakes of the state were made on only a few dates so that a comparison of num- bers would be subject to revision after a more complete knowl- edge of those lakes. So far as appears, however, Glovotrichia oceurs in vastly greater abundance in Lake Winnebago than in the other bodies of water from which collections were made. The only exception to this was a very large collection of Glovotrichia made on Pelican lake August 12, 1902. Other collections made on Pelican lake in preceding years, however, did not indicate so large a production of this plant as in Lake Winnebago. Sphaerella lacustris (Girod) Wittrock. This organism I have found a fairly constant constituent of the plankton of Green lake. During the first year it occurred in the collections from September until the next June. Dur- ing the second year it was found from early in August until the last of December. In the third year it appeared through the fall months, and after that the collections were discontinued. Its maximum of appearance seems to be from September to January. In Green lake it seems to be distinctly characteristic of the cold season. I have not found this form in Lake Winnebago, but it does occur in a number of the other lakes, generally in small num- bers, but in August, 1900, I found large numbers in Shawano and Pelican lakes. Although it is found in the plankton more in the colder sea- son, it does not follow that it lives in Green lake only at that time, for I have found it in enormous numbers in Dartford Bay in boats that were standing half full of water in the summer. Dinobryon. Dinobryon occurs in both Green lake and Lake Winnebago. In Green lake the largest collections have been in May, June, and July, but it may oceur in any month. In Lake Winnebago I have never found it in July and Au- gust, but it comes in with September, is found in small numbers fy, VA ( IAEA RRA EL OF Nw 18 PLANKTON OF WINNEBAGO AND GREEN LAKES. in the fall and winter, and reaches a maximum of numbers in March. In the European lakes, according to Apstein and Zacharias, this genus occurs from April or March to. August, but it would appear from my collections that it may be found in our lakes at any time except that in Lake Winnebago it fails at the hottest time of the year. It would seem to be a fair presumption that the heat of mid-summer is unfavorable to its growth although it has been found in Green lake in great numbers in July. Synura uvella Ehrenberg. I have found Synura in Green lake only in two collections made in May, 1901. In Lake Winnebago it sometimes forms an important ele- ment in the winter plankton. I have found it in the months from November to April, with the largest numbers in January, February, and March. It seems to be very distinctly confined, in its development, to the months when the lake is covered with ice. Uroglaena. I have not found Uroglaena as a constituent of the plankton of either Green lake or Lake Winnebago. I did find it, how- ever, in large numbers in the plankton of the Eagle River lakes in August, 1901 and 1902, and it seems probable that in some shallow lakes it may be in the summer an important element in the plankton. Ceratium hirundinella O. F. Miiller. Only once did I find Ceratium in Lake Winnebago in any considerable numbers,—in a collection made August 22, 1900. Tt cannot be said ever to form an important part of the plank- ton of this lake. It may be found at almost any time of the year but always in small numbers. In Green lake it is distinctly a summer form. It is almost entirely absent except in the months from July to October, in- clusive. In the summer of 1899 its maximum was reached ' re O ae A ) ; | 2 eae ¥ yA RF ee es | a) S ee Le ba en yt Ar wd Te en ae re SNARY NER IE BE ie en fa Os: _— pe ‘A JA pon : Soy UY Vwer = Ward- ( 4 D sje i ANNUAL DISTRIBUTION OF THE ORGANISMS. 19 the last of July, in 1899 its greatest development was early in October, and in 1901 it reached a maximum about the mid- dle of September. The total production in 1901 was much greater than in the preceding years. : , Codonella lacustris Entz. hai Codonella does not occur in Green lake. In Lake Winne bago it is found most abundantly in the winter months, although it occurs at other times of the year. It is never pres- ent in sufficient numbers to affect the total plankton. Hpistylis galea Ehrenberg. Epistylis was found in small numbers in the plankton of Lake Winnebago in the fall of 1900 and 1901. I found it also in the plankton of Birch lake in August, 1900. Anuraea cochlearis Gosse. ~ Anuraea cochlearts is found at all times of the year in both lakes. There is no uniform maximum period. Apstein states for Pléner See that the greatest numbers are found in July. Seligo finds for various lakes maxima in May, June, July, and September. The largest single collection in Green lake was made in Au- gust, while the largest collection in Lake Winnebago was made in January. The occurrence of the species, however, was very erratic, and I can draw no conclusions as to its annual period- icity. Anuraea aculeata Ehrenberg. Anuraea aculeata was found in Green lake only in two col- lections,—in July and December, 1901, and then in very small numbers. In Lake Winnebago it was pretty constantly in the plankton from October or November until the next May. The largest single collection was in January, 1900. Thus Anuraea aculeata would appear to be a distinctly winter form. This agrees with the statements of Seligo and Voigt, but Apstein has found it a summer form. iN & e ; e 20 PLANKTON OF WINNEBAGO AND GREEN LAKES. I have, however, found it in other lakes in the summer. It occurred in August, 1901, in both Shawano and Stone lakes in small numbers. In August of both 1900 and 1901 it was found in large numbers in Birch lake. I have found it also in Cedar lake in March and June. It is evident then that Anwraea aculeata may occur at any time of the year, and I see no reason why in Lake Winnebago it should be limited to the colder months, for the conditions of Shawano lake are very similar to those of Lake Winnebago. Anuraea quadridentata Ehrenberg. Anuraea quadridentata I have not found in Lake Winnebago. It appeared in Green lake in 1901 from February through the month of April. Polyarthra platyptera Ehrenberg. Polyarthra is a perennial form in Lake Winnebago. Gen- erally speaking the numbers are greater from July to October, _ but in one year there was a very large production in February nd Wark: In Green lake it occurs from June through the month of October. I have never found it in the winter months. The European authors speak of Polyarthra as a perennial. The occurrence in Green lake would seem to be somewhat pecu- liar, and I cannot see what circumstances in Green lake should be more unfavorable to it than in Lake Winnebago. Triarthra longiseta Khrenberg. Triarthra is never found abundantly in either lake. In both it is found from June to November, and only occasionally in the winter months. Notholca longispina Kellicott. Notholca longispina is much more numerous in Green lake than in Lake Winnebago. In both lakes it may occur at any time of the year, with no pronounced maximum period. The largest. single collection in Green lake was in February, 1900. ANNUAL DISTRIBUTION OF THE ORGANISMS. a1 ran Loy ; Pe /} rj y ALP eee In general, the collections of the fall and winter months were larger than those of the summer. The conditions of a deep lake seem to be more favorable to the production of Notholca longispmna than those of a shallow one. Seligo states that it was found in greater numbers in the deeper of the Stuhmer lakes. Notholea foliacea Ehrenberg. Notholca foliacea is not a common member of the plankton of these lakes. J have found it in Green lake only once, on May 4, 1901. In Lake Winnebago I found it in collections made in the middle of February and in the middle of March, 1901. es Asplanchna sp. Paes pie An undetermined species of Asplanchna was found in Green 3. Fenny lake in January and March, 1900. In the same winter it was found in Lake Winnebago as early as November and was a fairly constant member of the plankton until the middle of March. Synchaeta pectinata Ehrenberg. Synchaeta pectinata occurred in Green lake in the winters of 1900 and 1901. In the winter of 1900 it was found in the months of February, March, and April. In 1901 it was found from January to March. It was found in a single collection also in October, 1900. In both winters the largest numbers were in the collections made on the twenty-third of February. In Lake Winnebago it is also a winter form with a somewhat more extended period of occurrence than in Green lake. I have found it in the months from October to April, inclusive, and in a single collection in June, 1901. This occurrence of Synchacta pectinata corresponds fairly well with the results obtained by European investigators. Ap- stein finds it a perennial form, with its maximum in the win- ter months. He states, however, that in his counting he has not distinguished the species of Synchaeta, and it would seem possible that pectinata did not occur in the summer months. 22, PLANKTON OF WINNEBAGO AND GREEN LAKES. Seligo says that S. pectinata occurs through the whole year with a maximum in September. Voigt (Voigt ’02) says that S. pectinata is generally absent in the summer months, but is found in the fall, winter, and spring, while other species occur in the summer. Conochilus volvox Ehrenberg. Conochilus was found in Lake Winnebago in the summers of 1899 and 1901. In 1899 it reached its greatest numbers in the last week in July. In 1900 I found the largest numbers July 9. In 1900 a few were found in October and November. I have not found it in any of the collections from Green lake, nor does it seem to be distributed very generally in other lakes. In September, 1899, I found it in Birch lake, in June, 1900, in Cedar lake, Washington county, in August, 1900, in Pelican and the Eagle River lakes, and in August, 1901, in consider- able numbers in one of the Clover Leaf lakes. While it is not at all uncommon in the summer months, its distribution seems to be somewhat erratic. Apstein finds a much longer period for Conochilus, but states that it is irregular in its maximum period. Voigt (Voigt ’02) states that the period for Conochilus vol- vox extends from August to November, but other species of Conochilus may occur in the winter months. Diaptomus minutus Lilljeborg and sicilis Forbes. D. oregonensis does not occur in Green lake but its place is taken by D. minutus and D. sicilis. In a former paper (Marsh ’97) I discussed the annual distribution of these Diap- tomi, and the curves given in Plate II, while they modify the conclusions reached at that time, do not do so in any material way. As in my former work, I did not in the counting dis- tinguish between the two species, but, in every case, careful ex- amination was made as to the presence of the two species. I have very little to add to the statement already made (Marsh 97, 193) in regard to the annual distribution of these two species. D. minutus occurs in the months from July to Decem- WISCONSIN GHoL. AND Nat. Hist. SurvEY. BULLETIN No. XII, Puatp II. JULY AUG. SEPT. OCT. : : : : : : MAY JUNE Curves of annual distribution of Diaptomus sicilis and Diaptomus minutus per square meterin Green lake, the numbers being reckoned in thousands. ui Rt oe ht ‘SpURsnNoy} Ul Pouoyoet Suroq saoqumnu oy} ‘OFeqouulM oY Ul 1ojoM oavnbs 10d sisuauobou0 snwozdnrg jo UOij{NqII4sSip [vnuUE Jo seAIND Nese Cor L061-O061- 77 0061-6681 Sol ost Sanne AVIN ‘ddv ‘'UVIN ‘aaj i ; : ‘ONY AINE ‘TIL DiVId ‘I1X ‘ON NigatIng “KGAUOG USIP] “LVN GNV “10d NISNOOSTAL “MARSH COLLECTION” ANNUAL DISTRIBUTION OF THE ORGANISMS. ioe ber, inclusive. JD. sicilis is found from the last of September or first of October until the first of July. D. sicilis is rarely present in the summer months as D. minutus is seldom found in the winter and spring months. In considering the curve, then, it must be remembered that the summer maxima are for minutus while the winter maxima are for sicilis. In Novem- ber and December and again the last of June the species are found together in the plankton. In the three years under ob- servation the greatest production of minutus was not far from the first of August with a smaller fall maximum the last of September or first of October. This differs from the only com- plete curve in my former paper in that then the greatest maxi- mum was in September. D. sicilis reaches its greatest numbers in February and March. It may be remarked that this maximum of D. sicilis corre- sponds with the maximum period of development of Asterzo- nella, but whether there is any causal relation between the two I am unable now to say. Diaptomus oregonensis Lilljeborg. Diaptomus oregonensis is the only form of the genus found in Lake Winnebago, and is the common form in the greater majority of Wisconsin lakes. The curves of annual occurrence are shown in Plate III. It will be noticed that in the first summer there were three marked maxima, the last of July, the middle of September, and the first of November. There was then a rapid decline, a constant winter minimum during January, February, and nearly through the month of March, when there commenced a slow increase in numbers. In the second year the maxima were in the middle of August, the early part of November, and a heavy maximum in the next June. In the third year the summer maximum occurred the first of September with a fall maximum the early part of No-! vember. In comparing the three years the uniformity of the November maxima is very remarkable. With the July maxi- mum of 1900 there is nothing to correspond in the other years. 94 PLANKTON OF WINNEBAGO AND GREEN LAKES. We can say, in general, that Diaptomus oregonensis occurs in» its greatest abundance during the months from June to Novem- ber, inclusive, that it is found only in very small numbers from the latter part of November until the last of March; that it has a constant fall maximum and one or more mid-summer maxima which occur between the last of July and the first week in September. So far as I know there are no preceding obser- vations on the annual periodicity of D. oregonensis except those recorded by Birge (Birge ’97). The curves of D. gracilis and D. graciloides as recorded by Apstein, Steuer, and Seligo correspond in general with these curves, but differ in details. Especially noticeable is the state- ment of Apstein that the maximum of D. graciloides in Lake Plon occurs in the winter. In comparing my results with those of Birge, while there is a general resemblance in the curves, there are certain marked differences. He states that in Lake Mendota the smallest catches of the year were made in the latter part of April, and he infers that the conditions of life are harder for them after the going out of the ice. In Lake Winnebago there was a distinct increase during the month of April with a drop during the first half of May. J am unable to explain this increase, but it does not appear that the going out of the ice worked any hardship in the case of the Lake Winnebago Diaptomus. In Lake Mendota there seems to have been no increase corre- sponding to the November maximum of Lake Winnebago. It is possible that this fact has some bearing upon the question of the effect of temperature upon the species. Birge (Birge ’97, 326) states that the reproduction of D. oregonensis is more promptly checked by a fall of temperature than is that of any other species. Of course there is no question of the truth of the general proposition that the reproduction of this Diaptomus is dependent upon higher temperatures. The general charac- ter of the curves shows that at once. If, however, it were par- ticularly sensitive to a decline in temperature, should we not expect fall reproduction to stop soonest in the lake that cools off the most quickly? Jake Mendota has a maximum depth “‘Sporpuny, UI pouoyoor SuIOg StoqwnuU oY} ‘OdLGoUUTM YL] UL JoJoUT aivnbs 190d spysnon), Danyosidy JO WOLNQIAASIp [vnuUUL FO S8AINy) Oo} os! 002 OS2d Oo€ 1061-0061 0061-668!—___ ose OOV JInar AVIN ‘ddv “dVIA ‘a34 NUS ‘94a “AON “LOO ‘lda3S ‘SNV Ane ‘AI GiVId ‘IIX ‘ON Niga1iag ‘KHAUNG “GSIET “LVN GNV “LOM NISNOOSTIM ‘Sporpunyq, UL Povoxyoor Suyod Stoquinu oy} ‘ol Woory Ul dojour vaunbs a9d si.ysnon, vunyosrdy JO WOIUGLYSIP PVNUU JO seAmog LO61-OO6 17>" ~~ 006 |-6681—__ 002 OSe Inner AVIA ‘ddv AVIA ‘@34 NVP ‘OAG “AON ‘LOO ‘Ld3S ‘ONY AINE "A GLVId ‘JIX ‘ON NI“aTiIng 4 “AMAUNG “USTEL “LVN GNV “TOU NISNOOSTAL ANNUAL DISTRIBUTION OF THE ORGANISMS. 25 of about eighty feet, while the maximum depth of Lake Win- nebago is only about twenty-five feet, and because of its greater extent is doubtless much more affected by the winds. It seems to me that if the species were especially sensitive to tempera- ture we should expect the fall maximum in the deeper lake rather than in the shallower, as seems to be the case. Eypischura lacustris Forbes. Epischura is distinctly a summer form. As shown in the curves (Plates IV and V) it appears sometimes as early as May and may be found as late as December or even January. In Green lake the larval forms appear in February and March. This is not indicated on the curves of the Hpischura plate, as in the counting the Hpischura larvae were not distinguished from those of the other copepods. The period of maximum deyel- opment oceurs in July or August. It will be noticed that the spring increase occurs a little later in Green lake than in Lake Winnebago, and that the summer maximum of Green lake is also a little later than that of Lake Winnebago. Hpischura remains in Green lake, too, later into the fall than it does in Lake Winnebago. This is without doubt due to the fact that Green lake warms up so much more slowly, and cools off in the fall with corresponding slowness. The curves conform quite closely with the results given in my ’97 paper, except that in the winter of ’95 there was a large rise in March. ‘This difference is accounted for by the fact that in the ’95 collections a distinction was made between the Epischura larvae and the other copepod larvae. The annual occurrence of Wpischwra in Lake Winnebago re- sembles very closely the results given by Birge for alake Men- dota. : The nearest European relative of Hpischura, Heterocope, is stated by Apstein to occur from July to November, with a max- imum in the summer, thus showing a resemblance in its period- icity to Lpischura. 26 PLANKTON OF WINNEBAGO AND GREEN LAKES. Timnocalanus macrurus Sars. Limnocalanus only oceurs in deep lakes, so it is not found at all in Lake Winnebago. In Green lake it is found at all times of the year. In my former paper (Marsh ’97) I stated that its maxima were in May and November. ‘The curves from the present series of observations (Plate V1) seem to confirm the former results, although the spring maximum occurs as early as April in some years, in others as late as June, and in the summer of 1900 the greatest number during the year was in July, although there had been a marked rise in April. Dur- ing the winter months most of the individuals are larval forms. It will be noticed that the maxima of Limnocalanus are not very widely different from the smaller numbers found at other times. This is doubtless due to the habits of this species, which, as I have shown before, prefers a low temperature of the water, and during the summer months is found to very little extent above the thermocline. In the winter it is found at all depths. While, for the sake of the lower temperature, it suc- ceeds in adapting itself to the stagnant conditions of the deeper waters of the summer, it does not flourish at that time as it does when, the temperature being favorable, it can find a home at any depth. Cyclops brevispinosus Herrick. C. brevispinosus is found in both Green lake and Lake Win- nebago. The curves (Plates VII and VIII) show that it should be ranked as a summer form, although it may be found at all times of the year. In the three summers under observa- tion there was a marked increase the latter part of July or the first of August. In 1902, however, the greatest number of the year was found about the middle of September. In Green lake apparently there may be expected a great in- crease in the latter part of June or in July. In December, 1902, however, I took the largest collections of the whole pe- riod of two and a half years. These results correspond with the results reported for Green lake in my former paper (Marsh 97). WISCONSIN GEOL. AND Nat. Hist. SURVEY. BULLETIN No. XII, Puatn VI. JULY AUG. SEPT. OCT. NOV. DEC. JAN. FEB, MAR. APR. MAY JUNE 500 (S33 200 250 200 150 100}- ay - Curves of annual distribution of Limnocalanus macrurus per square meter in Green lake, the numbers being reckoned in hundreds. ° WISCONSIN Gron.,.AND NAT. Hist. SURVEY. BuULLUTIN No. MII, Puarn VIL. 250 —__ 1899-1900 __-.-. 1900-1901 300 250 200 150 100 1 SO - \ \ | eee Curves of annual distribution of Oyclops brevispinosus per square meter in Lake Winnebago, the numbers being reckoned in hundreds. pee ee WISCONSIN GOL. AND NAT. HIST. SURVEY. - BULLETIN No. XII, PLuarn VIII. JULY AUG. SEPT. OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE 400 3 1899-1900 See OOO9On Curves of annual distribution of Cyclops brevispinosus per square meter in Green Lake, the numbers being reckoned in hundreds. *Spo.rp SUT 3 B Spotpunyg Ul powoyIe. sulod Sitequinu oY} ‘OsvqoUUIM 2YVYT Ul JoJo oavnbs aod snj19yajnd sdojaip JO WorjnqtajstIp [enuue gO SsoAIngD = OS 1061-0061 0061-668 | ——— 3nar AVIN ‘ddv “UV ‘@34 “NVE “913G “AON “LOO “Ld3s ONY AINC ‘XI SIVId ‘IIX ‘ON Nigating ‘i : AGTAUOY “LSIE, “IVN GNV “IOUS NISNOOSTAL ANNUAL DISTRIBUTION OF THE ORGANISMS. oY Birge reports for Lake Mendota that the largest collections were made in May. ‘This does not correspond to the results of either Green lake or Lake Winnebago, although in one year there was a considerable rise in Lake Winnebago in May. In gen- eral it may be stated that C. brevispinosus is a perennial form, flourishing especially in the months from May to October. Cyclops pulchellus Koch. Cyclops pulchellus does not occur in Green lake. In Lake Winnebago it is found from early October to the last of June. As the curves show (Plate IX) it has no very pronounced maximum, but it is evident that it is present in the greatest numbers in May or June. This species is then, in Lake Winnebago, distinctly a winter species. Cpe h—4 ‘Ci DistrisuTion oF C. brevispinosus ann C. pulchellus In Wis- consin LAaxus. While I have found C. pulchellus in Lake Winnebago only in the months from October to June, inclusive, it is the com- mon limnetic form in some other lakes. This is notably so in the Great lakes. In certain of the Wisconsin lakes, so far as my observations have gone, C. pulchellus is always present as the limnetie form as C. brevispinosus is in Lake Winnebago and Green lake. I have gone over very carefully the list of lakes, from which I have had collections, to determine, if possible, what is the factor which makes one lake a brevispinosus lake and another a pulchellus lake, but so far without entire success. The following lakes, so far as I know, always have C. pul- chellus: Lake Geneva, Elkhart, Chain o’ Lakes, Cedar lake Washington county, Birch lake, Stone lake, Sand lake, Lake Michigamme, and Long lake Fond du Lae county. All other examined lakes have brevispinosus. All the lakes hav- ing pulchellus, with the exception of Sand lake, are of the deeper lakes, and Sand lake has a maximum depth of fif- teen meters, thus being one of the deeper lakes of this type. Cptebrtled (por) [dnd —~ Meth d, de, Nanar_4_ lAoy— 98 PLANKTON OF WINNEBAGO AND GREEN LAKES. On the other hand all of the lakes having brevispinosus, with the exception of Green lake, are of the shallow lake type. In- asmuch as pulchellus is found in the colder waters of the Great lakes, it would be a natural inference to suppose that its pres- ence in Lake Winnebago in winter had immediate relation to the winter temperature of the water, and that it might be found during the summer in other lakes where the water retains a low temperature through the year. It seems impossible, however, to establish any such rule. Generally speaking it is true that in the shallower lakes brevispinosus is the common limnetic form, while in the deeper lakes, which have a marked thermo- cline in the summer we find C. pulchellus, but the exceptions are so startling as to destroy most of the effect of the generaliza- tion. Cyclops Leuckarti Sars. C. Leuckarts oceurs in both Green lake and Lake Winnebago, but at somewhat different periods. In Lake Winnebago it is perennial, but the numbers in win- ter are very small. It is found in considerable numbers from April to the last of October. It is apparent from the curves of frequency (Plate X) that its maximum period is in July and August, although in one year there was a great increase in May. In Green lake, on the other hand, it appears to have a fall maximum, although the total numbers observed were so small as to make one careful about drawing any exact imferences. The cause of the difference in the curves of the two lakes is difficult to state. If the maximum of Green lake occurred somewhat later than that in Lake Winnebago it might be thought that the difference was due to the fact that the deeper body of water is heated more slowly, but in the curve of 1900 the maximum in Green lake is late in the fall, so that this can not be considered the real reason. WISCONSIN GHOL. AND Nav. Hist. SuRVEY. BULLETIN No. XII, Puarn X. JULY AUG. SEPT. OCT. N DEC. JAN. FEB. MAR. APR. MAY JUNE OV. 400 Woranfed uals) foe = 1900-1903 24) GX) +—+ 1899-1900 —=— 1900-1901 Curves of annual distribution of Cyclops Leuckarti per square meter in Green lake and Lake reckoned in hundreds, Winnebago, the numbers being Pe AN Fite oil ee oe rare Dudes ‘SPpUvsnOy} UL Poloyoor SuJod StoqumMuU oy} ‘oyv, WootH uy Aojou oavnhbs aod smusyud sdojoAg yo uornqiwysrp [wnuur Jo soaang oot 1061-0061 ------- 0061-6681 Ocl OVI anne AVIN “ddvV “UVIA ‘q34 “NVS ‘94¢0 “AON “LOO “ld3aS ‘SNnV AINE ‘TX GQivid ‘TIX ‘ON Niaariag “KMAMAG WSIELT “LYN GNV “TOU NISNOOSTAY ‘spuvsnoy} UL Pouoyoor Supod sdoquinu oy} ‘oyV] Wary) Ul Aojout oivnds aod ovarvy podedod Jo Wornd!ysTp [enuUv FO SoAmp OS okoy! OSI OOd OS2 OO€e LOS, === VOGI=OO6 Ne aaaas ONS LSS | —$——= OSE oov 3nne AYN ‘ddv “YVAN ‘a34 “NV ‘030 “AON 20) ldsiS = sO My Aqngr TIX GDiIVId ‘IX ‘ON Nigariag ‘KGAUAG “LSIET “LVN GNV “IOM) NISNOOSTAA ‘SpuvSHOY) UL peuoyoor Suroq stoqttnu oy} ‘oOSeqouurAA dYyLY wr rojowr orunbs tod ovarvy podedoos Jo Wormnqiaystp [enuuV Fo soAmp OS COL Ost 002 | OSC OOe t1O61t-OO6G L- ---—- 006 1-668 | ———_ OSE anaer AVIN ‘Udy ‘UVIN ‘aad ‘NWe ‘94a “AON ‘LOO ‘ldas SNV AINE TIX Givid ‘TIX ‘ON Nitating ‘ATAWAS “LSIET “LVN CNV “LOUD NISNOOSTAL ANNUAL DISTRIBUTION OF THE ORGANISMS. 29 Cyclops prasinus Fischer. C. prasinus occurs in Lake Winnebago only in very small numbers, so that a curve of annual oceurrence would mean very little. I have found it in every month of the year except in March, April, and May. The largest numbers I have found in September and October. In Green lake (Plate XI) it is a perennial form, but occurs in considerable numbers only from July to November, inclu- sive. In 1899 there were marked maxima the first of August and the first of October. In 1900 there was a similar increase in August, a few days later than the preceding year, and a fall maximum the first of November. In 1901 there was only one maximum and that occurred just after the middle of Septem- ber. C. prasinus then seems to be distinctly dependent upon the summer temperature for its period of greatest development. COPEPOD LARVAE. Under this head were counted, not only naupli, but all forms of immature copepods which were not sufficiently advanced in structure to be specifically determined. Inasmuch as it is im- possible to determine the species of these larvae, it is difficult to explain the maxima of the curves (Plates XII and XIIT) as due to the increase of particular copepods. It is only by comparing these curves with those cf the various species that we can conjecture to what species a given maximum is due. In many cases these maxima are doubtless due to more than one species. A glance at the plates shows that the total numbers of larval forms in Green lake are considerably larger than in Lake Win- nebago as only once in the two years and a half under observa- tion did the number in Lake Winnebago much exceed that in Green lake. This is no more than would be expected from the fact that the copepods play a much more important part in the plankton of deep water lakes than they do where the water is shallower, In Lake Winnebago larval forms are found at all times of 30 PLANKTON OF WINNEBAGO AND GREEN LAKES. the year with two pronounced maxima, one in the spring and one in the summer or early fall. In the summer of 1899 the summer increase was distributed from July to December, with no great rise at any time. In the summer of 1901 there was a single maximum in the middle of July, while in 1902 this maximum did not come until the first of September. In the spring of 1900 there was, about the first of April, the largest number found at any time in the whole period under observa- tion. In the next year, 1902, the maximum came about the middle of June. It is extremely difficult to correlate these curves with those of the mature copepods. The summer increase is doubtless largly composed of Diaptomus oregonensis and Cyclops brevis- pinosus, with some specimens of Cyclops Leuckarti and Hpis- chura. A comparison of the summer curves of these species shows a very close relation with the curves of larvae. The win- ter larvae are probably entirely of Cyclops pulchellus. The spring maximum is composed of the three species, Oyclops Leuckarti, Cyclops pulchellus, and Diaptomus oregonensis. In Green lake the curves resemble in general those of Lake Winnebago, with the exception of the marked increases in the winter months. In the three summers under observation there was a single maximum coming in the successive years in July, August, and September. J know of no reason why there should have been this difference. In the summer the larvae probably belong to all the species of copepods except D. sicilis, Limno- calanus, and Hpischura. The rises in the winter months are due largely to the two latter forms. I have found larval Hpis- chura only in February and March. The increase in October and November is because of the coming in of Diaptomus sicilis. The rise in the curve in May and June is doubtless largely due to the increase in D. minutus, which later forms one of the chief elements in the plankton. Diaphanosoma brachyurum Liev. Diaphanosoma is distinctively dependent for its development upon the high temperature of the summer months. In Lake ‘Sporpuny UL PouoYoodT SUTO( STOGWINU oY} ‘OSVGoUUTA OYV'T UL Topo orvnbs sod wnimhyooig vwosounydnrg JO Uornqiajstp pRnuur JO SoAang i \ i 4 ‘ \ 4INneF AVIA “AIX Gtvid ‘TIX ‘ON Nim@iiag 2 a ee . eee i noe Pos es poe 1061-0061 ~~ 0061-6681 ——— aaa hn. - HL 0002 ‘“Ldas “ONY AINEe ‘UVIA ‘OAad “LOO “RUAMOAG “GSTELT “DYN GNV “TOMS NISNOOST AL ‘Sporptnt, Ur potioyoor Suyoq Sioqttint otf} ‘oxyuy tooty ur dojyout orvnbds sod mupohiy mruydog Jo WOTNGIAYStp [vnuuv JO SOAIM;) COS LAYS} —— Ina AVIA ‘ddvV ‘YUVA ‘aad ‘Nw ‘O40 “AON ‘LOO ‘Ld3as ‘ONY AInNe ‘AX Divid ‘TIX ‘ON Nigaiinag “AWUAUNAG “LSIEL “UVN CNV “LOM NISNOOSIA\ waungey “u~ | MAT been tht Winahallentren bon ANNUAL DISTRIBUTION OF THE ORGANISMS. 31 Winnebago (Plate XIV) it appears as early as the middle of May and reaches its maximum in July or August, then rapidly diminishes, to disappear entirely the last of October. In Green lake it does not appear ordinarily until into July, and reaches its maximum in August or September. Here, too, it disappears the last of October. These results compare very closely with those reached by Birge for Lake Mendota and those noted by the European authors, Apstein, Fric and Vavra, Burkhardt, Steuer, and Seligo. Tt will be noted that the season for Diaphanosoma in Green lake is later than in Lake Winnebago, as we would expect, be- cause of the more rapid warming of the shallower body of water. The total:number in Lake Winnebago, too, is greater, and the maximum much more sharply marked. Daphnia hyalina Leydig and D. retrocurva Forbes. Under this head I have placed all the common limnetic Daph- nias, without attempting a closer specific distinction. In Green lake I think the form is retrocurva, while in Lake Winnebago both hyalina and retrocurva are found. In Green lake Daphnia may be found at all times in the year but between January and the last of May only in occasional specimens. Its principal time of life is between the first of June and the last of December. The results of the three summers given in Plate XV, compared with the curves of my former paper (Marsh ’97), do not give sufficiently uniform results to in- dicate maxima occurring with any great regularity. In the sum- mer of 1899 there were two distinct maxima, one the middle of July and one about the middle of October. In 1900 the two maxima were the last of August and the first of November, while in 1901 there were three maxima, all less pronounced than in the preceding years, one in July, one the latter part of August, and one the first of November. The curves would seem to indicate the common occurrence of two pronounced maxima, one in July or August, and one in October or Novem- An adeaia 4 Vv 39 PLANKTON OF WINNEBAGO AND GREEN LAKGS. ber. The curves of my ’97 paper indicate the same general principle. In Lake Winnebago (Plate XVI) the maxima during the summer months bear a fairly close resemblance to those of Green lake, but there is, in addition, a pronounced maximum in May or early June. This spring maximum may be due to the increase of hyalina, as Birge’s results would indicate the ex- istence of a spring’ maximum for this species. A comparison of the work of Birge on Lake Mendota and the published results of the European authors Zacharias, Apstein, Burckhardt, Seligo, and Steuer shows that the occurrence of limnetic Daphnia is very similar the world over, the winter months having the minimum of production, and the greatest numbers appearing in the summer and fall. The absence of the spring maximum in Green lake is doubtless due to the slow warming of the deep body of water. Daphnia pulex var. pulicaria Forbes. This species I have not found at all in Green lake. In Lake Winnebago it appeared May 11, 1900, and was found in large numbers in June and then entirely disappeared. In 1901 I found it in a single collection,—that of June 8. When it occurred it was in the bottom waters, and was very noticeable because of its size. It is possible that scattering in- dividuals at other times were counted as hyalina, but if it oe curred at all it must have been in very small numbers. Birge (Birge ?97) has discussed in detail the occurrence of this species in Lake Mendota, stating that it occurs there in num- bers only in the odd numbered years. This does not seem to be true in Lake Winnebago. He also states that it is confined to the region of the thermocline, being limited above by the high temperature of the water and below by the impurity of the bottom waters. If this were true it would explain the dis- appearance of this species in Lake Winnebago in summer, be- cause this lake has no thermocline, and the whole body of water is heated to a high degree. It would seem that the conditions WISCONSIN GroL. AND Nat. Hist. SURVEY. BULLETIN No. NII, PuaAtn XVI. JULY AUG. SEPT. OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE ——. 1899-1900 yeas ssecs 1900-1901 Curyes of annual distribution of Daphnia hyalina and D, retrocurva per square meter in Lake Winnebago, the numbers being reckoned ; in hundreds, ae : at % yaa ‘SPULSNOY} UL PowoOYoo#t Suroqd Stoquinu oy} ‘oyL] WootH Ul Aojout orvnbs 10d nunusog Jo wornqiaystp penuue jo soAmng oot 002 NOSSO OG = 0061-6681 3anar AVIN ‘Ud “YVAN ‘a334 ‘NYE ‘93a ‘AON “190 ‘Ld4aS ‘OAV AINE TIAN @tvtd ‘TIX ‘ON Nimaring “AMAWAG WLSTELT “IVWN GNV “TOY NISNOOSTAL w ANNUAL DISTRIBUTION OF THE ORGANISMS. 33 in Green lake would be peculiarly favorable for Daphnia pul caria, but I have never found it, although my collections have now covered a considerable number of years. In the other lakes examined in this investigation I found Daphnia pulicaria only in Shamrock and Pansy of the Clover Leaf lakes and in Pelican lake in two years. In the Clover Leaf lakes it occurred below the thermocline. Its occurrence in Pelican lake was somewhat unexpected, as this lake has no thermocline, and the species was found in August, after the lake was thoroughly warmed up. In former collecting trips I have found Daphnia pulicaria in the deep waters of Lake Beulah in July and August, and Pro- fessor Birge (Birge ’97) has already noted that it is common in the deep waters of the Oconomowoc lakes, which probably should be classed with the small deep lakes. Bosmana. In Lake Winnebago I have not found Bosmana at all in the months of July and August. In 1899 it did not appear until the first of December, and very few were found in the winter months. There was a very large increase about the first of June. Then it abruptly disappeared and reappeared the last of September. There was a fall maximum the first of Novem- ber, and then a rapid decline. During the winter months there were very few, and no marked increase until the first of June, 1901, when there was an increase corresponding to that of the preceding year. It then disappeared and was found again the first of October, when it commenced to increase with great rapidity. In Green lake, as shown by the curves (Plate XVII) Bos- mina occurs at all times of the year. Comparing these curves with the curves in my former paper (Marsh ’97) it would ap- pear that we may expect Bosmina to have a fall maximum in November or December. After this maximum there is a sharp decline and the number then grows gradually smaller until June or July, when generally there is a slow increase 3 34. PLANKTON OF WINNEBAGO AND GREEN LAKZS. followed by a rapid rise in the fall, which may come as early as September, but more commonly occurs in October or Novem- ber. In 1900, by far the largest number of the year occurred in July. Nothing like this appeared in the other years, al- though there was an increase in July, 1899. I think it can be said safely that Bosmina has two annual maxima, one in the late spring or early summer, and one late in the fall. In comparing the two lakes under consideration we find that the spring maximum occurs earlier in Lake Win- nebago than in Green lake, probably due to the fact of the more rapid warming of the water in the shallow Lake Winnebago. In some years the spring maximum fails to appear in Green lake. The fall maximum seems, on the whole, to appear in Green lake somewhat later than in Lake Winnebago. If this maximum is dependent on some conditions following the fall cooling of the water, this later appearance in Green lake is easily explained. But so little is known of the life history of Bosmina that one would hardly feel safe in hazarding an ex- planation. In comparing my results of the annual distribution of Bos- mina, there seems to be a good deal of discrepancy, but prob- ably the differences can be explained either by differences in local conditions or by the fact that most of the statements have been based on observations carried on for only a comparatively short time. No other observations, so far as I know, have been published in America, and the statements of Kuropean authors would indicate that in some cases there were two distinct max- ima, but not in others. Eurycercus lamellatus O. ¥. Miiller. Eurycercus lamellatus does not occur in the limnetic plank- ton of Green lake, but in Lake Winnebago (Plate XVIII) it was an important element of the summer plankton in 1899 and 1900. Curiously enough I found it in only one collection in 1901,—that of June 8. In the summer of 1899 it was found in great numbers about the middle of July, but had almost dis- WISCONSIN Grou. AND Nat. Il1st. SuRVEY. BULLETIN No. XII, PuAtre XVIII. 700 JULY AUG. SEPT. OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE —_____ 18 99-1900 sore age 1900-1901 | || | _| | | |) coe | Curyes of annual distribution of Burycerus lamellatus per square meter in Lake Winnebago, the numbers being reckoned in hundreds. 200 Pan ‘Spoipuny Ul pouoyoot Sureq Sioquinu oq} ‘os eqouul MA oYeT Ul Tojo otends acd Ssnarv.apy as snsopryp JO UOTINGIAJSTP [RnNUUB JO S9AMpD 002 OOvV 009 00s LO61 -—— 0001 106 |-OO6 1 ------- : 006 1-668 1 —— 00z1 ; oOvL 4anar AVIA “ddv “UVIA ‘e434 NYS ‘O34qd “AQN “LOO ‘idas “ONY AVAL ‘XIX Giv1d ‘TTX ‘ON Nimating “ROAWMAS SIE, “LVN CNV “TOMS NISNOOSTAY ANNUAL DISTRIBUTION OF THE ORGANISMS. 35 appeared by the first of August. There was a rapid increase the last of August, another decrease and a rise again about September 20. It then decreased until the middle of Octo- ber, and had entirely disappeared in December. In July and August it was perhaps the most noticeable element of the plank- ton, its greater specific gravity causing it to settle first in the centrifuging process. In 1900 it appeared as early as March, but did not commence to increase until well into June, and reached a single maximum about the first of August, then de- ereased rapidly and disappeared about the first of October. In 1901 it is evident that some untoward circumstances must have prevented its development. In the collections made early in July, 1899, Hurycercus was - much more abundant over the mud bottom well out in the lake than it was over the stony bottom nearer shore. Late in July the conditions were reversed, that is, Hurycercus was more nu- merous over the stony bottom nearer shore. An attempt was made to correlate this fact with the movements of fish, but not with entire success. It was found that while Hurycercus was prevalent, it was an important article of food for the sheeps- heads, and apparently there was some movement of the sheeps- heads corresponding to the change in position of the greatest numbers of Hurycercus, but the observations were not suffi- ciently numerous so that any final statement could be made. Chydorus sphaericus O. F. Miiller. Chydorus occurs only occasionally in Green lake. In the summer of 1899 none were found. Considerable numbers were found in October of 1900, and it continued in small numbers in the collections until January, but was found in none of the later collections. In Lake Winnebago (Plate XIX) it appears to be a perennial form. In the summer of 1899 it had a sharp maximum early in August. It then declined rapidly and only few were found until July of 1900, when there was a sudden and great increase. A still greater increase occurred about the first of November. 36 PLANKTON OF WINNEBAGO AND GREEN LAKES. I have made no systematic collections from other lakes, but I have found Chydorus in great numbers in Stone, Sand, and Pelican lakes in September. I think we may say this,—that Chydorus is a perennial form, reaching its greatest numbers in the months from July to No- vember, with its maximum probably in October or November, but with sometimes a very marked increase also in July. Leptodora hyalina Lilljeborg. od Plate XX shows the annual distribution of Leptodora in Lake Winnebago. It was entirely absent from both lakes from November until May. In Lake Winnebago it occurs as early as the beginning of May, but in Green lake it does not appear until into July. It disappears in Green lake, too, early in- September. In both lakes its principal occurrence is in the months of July, August, and September. The occurrence in Lake Winnebago corresponds very closely with Birge’s state ment in regard to Lake Mendota, although he has found them there as late as December. The observations of Burckhardt, Steuer, and Seligo in Eu- rope in regard to this species show that the occurrence there is very nearly the same as in this country. Cypris. An undetermined species of ostracod was found in both Green lake and Lake Winnebago collections. In Green lake it was found in September and October of two years and in Feb- ruary and March of one year. In Lake Winnebago its range seems to have been from the first of April to the last of Septem- ber. It was very much more abundant in the summer of 1899 than in that of 1900. It was not at any time present in suf- ficient numbers to play any noticeable part in the total amount of plankton. The Bloom. The phenomenon of the “bloom” or the “working of the lakes,” or the “breaking of the meres” as it is called in Great WISCONSIN Grom. AND NAT. Hist. SURVEY. BuLunrin No. XII, Puare XX. ] JULY SEPT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE —___— 1899-1900 _..----.. 1900-1901 Curves of annual distribution of Leptodora hyalina per square meter in Lake Winnebago. ; u ANNUAL DISTRIBUTION OF THE ORGANISMS. Bld Britain, should receive a little attention although it has been thoroughly discussed, in its general aspects, by other authors. This phenomenon is especially marked in Lake Winnebago in some summers. It is due, of course, to the enormous growth of the plants of the plankton, that growth being particularly fostered by the hot weather of midsummer. The plants espe- cially concerned in forming the bloom are Clathrocystis, Ana- baena, Aphanizomenon, Oscillaria, Lingbya, and Glovotrichia. The times of occurrence of these plants have already been no- ticed in the discussion of the individual constituents of the plankton. At the middle of August, in some summers, on a still day, the surface of Lake Winnebago is apparently a solid, opaque green. Some of this material decomposes, and as the eurrents slowly move along the surface material, it shows a wavy streaked appearance like the surface of polished mala- chite. Its intrinsic beauty, however, does not attract the aver- age person, for he looks upon it as “scum,” and he thinks of it simply as an evidence of filth. This material is thrown upon the shores by the waves until the rocks alongshore are completely covered with it, and it may in its decay become very offensive. Following the maximum period of the “bloom” Cladophora ap- pears and covers the littoral rocks with a thick mat of green. This great growth of “bloom” naturally attracts the attention of the non-scientific observer, and many absurd explanations of its presence are given. The most common one in Oshkosh is that it is a mass of seeds coming from the marshy shores of the Fox and Wolf above Oshkosh. Doubtless the Anabaena and Gloto- trichia have given rise to the supposition that the bloom is a mass of seeds. The decomposition of Glovotrichia produces a blood red coloring matter which is sometimes very noticeable on the shores of Lake Winnebago, and has led people to question as to whether the lake is not affected by one of the plagues of Egypt. When the water is still the plants of the bloom are in greatest abundance, close to the surface, and are distributed very uni- formly over the lake. Frequently, in the latter part of July 88 PLANKTON OF WINNEBAGO AND GREEN LAKES. and in August, there may be seen floating about yellowish green masses of a more or less spherical outline, perhaps as much as three inches or more in diameter. These masses, which are com- posed of aggregations of Aphanizomenon mingled with scattered fronds of Gloiotrichia and Anabaena, have very little coherence and elude the collector by falling in pieces almost at a touch. As is evident from the discussion of the occurrence of the algal constituents of the plankton, the bloom is not a prominent feat- ure of the deep lakes,—in fact in some years the growth of these algae is hardly noticed by the ordinary observer,—and of the shallow lakes few seem to produce so large an amount as is seen in Lake Winnebago. Of the lakes under observation, Shawano and Pelican were the only ones that could be compared at all with Lake Winnebago. ANNUAL DISTRIBUTION OF THE TOTAL PLANKTON. Plates XXI and XXII shows the annual distribution of the total plankton in Green lake and Lake Winnebago during the two years under observation. An examination of the curves, while it shows marked similar- ity in the production of the years studied, shows also almost as marked differences. In general it may be said that the sum- mer months are the time of greatest productiveness, although Green lake shows an exception to this. We notice also that the successive years not only differ somewhat in the time of maxi- mum production, but that there is a marked difference in the total amount of plankton. In Lake Winnebago in the first year there were four periods of large production,—the last of July, the middle of September, and the early part of June. In the second year there was a single maximum which occurred early in September, with not even slight increases at other times. In the third summer there was a pronounced maximum in the last of July, with slight in- creases in September and October. In Green lake there are similar differences. WISCONSIN GEOL. AND Nat. Hist. SURVEY. BULLETIN No. XII, Puarw KNIT. OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE 1899-1900 os --.1900-1901. ee 1901 Priallll i roof AY A Curves of annual distribution of total plankton in Lake Winnebago per square meter, estimated in cubic centimeters. WISCONSIN GbrolL. AND NAT. Hist. SURVEY, BULLETIN No. XII, Phare NNIT. JULY AUG. SEPT. OCT. NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE 500 450 400 1899-1900 1900-190 ales -1901 350 [ease SS OO 300 Curves of annual distribution of total plankton in Green Jake per square meter, estimated in cubic centimeters. ANNUAL DISTRIBUTION OF THE ORGANISMS. 39 In the first summer the greatest amount of plankton was about the first of August and the middle of October. In the following February and March, however, the total of plankton was much larger than even in the summer months, while the greatest rec ord of the year was reached about the middle of June. From this point there was a decrease followed by lesser maxima the first of August and the first of September. There was then a steady decrease to a minimum in the middle of January. From this point there was an increase to a March maximum corre- sponding to that of the preceding year, but the total of this March maximum was much smaller than that of the March of the preceding year. It then fell toa May minimum, which was almost as small as that of the winter. This was followed by a slow increase to a single summer maximum in the latter part of July, from which there was a slow fall through the remainder of the summer and autumn months. CONSTITUENTS WHICH PRODUCE PLANKTON MAXIMA. Jt is a matter of great interest to determine what organisms are responsible for the maxima, and what are lacking at the minimum periods. Steuer has stated that the result of his work indicates that the general plankton curve follows closely the rotatoria curve. ‘This is hardly true of either of the lakes un- der consideration. But what organisms are responsible for these maxima? A comparison of the general plankton curves with those of the individual animals and plants shows no close relation between the total plankton and the species. There is this general relation that most forms are produced in greatest numbers in the months from May and June until October; this is especially true of the plants. But no one organism seems to have a controlling influence on the total amount of plankton, ex- cept in one or two particular cases. This is shown by a careful analysis of the plankton constituents at the various maximum periods. In the summer of 1899, in Lake Winnebago, there were two 40 PLANKTON OF WINNEBAGO AND GREEN LAKES. maxima. These correspond to the maxima of Hurycercus lamel- latus. Hurycercus is a very bulky form, and when it is present in considerable numbers is a large element in the total plankton. A careful analysis of the summer collections shows, however, that while Hurycercus was an important factor in these maxima, it was by no means alone responsible for them. They were rather caused by a general increase in a number of forms of crustacea, accompanied by a large development of the plants. In the maximum of June, 1900, Daphnia pulicaria, another bulky form, also reached its maximum development for the year. But at this time, too, other forms are as important in making up the total. There was a general increase of most of the crus- tacea,—ameong others Diaptomus oregonensis being very promi- nent. Many of the plants, too, were present in considerable numbers, especially Asterionella. In the summer of 1900 the maximum early in September was coincident with a maximum of Daphnia hyalina. But this was not in itself sufficient to produce the maximum. The real determining cause was the enormous number of Anabaena, Clathrocystis, and an unnamed alga. The winter maximum was characterized by an almost total lack of crustacea and algae, while rotatoria, diatomaceae, and protozoa in small numbers formed the bulk of the plankton. In the summer of 1901 there was one pronounced maximum the last of July. At this time there was a large number of crus- tacea, but the size of the collections was mainly caused by the enormous numbers of Anabaena, Lingbya, and Aphanizomenon. In Green lake the maximum of Aug. 1, 1899, was due to the large number of several of the entomostraca, especially of Diap- tomus minutus and Daphnia. ‘The increase of the first of Octo- ber was due mostly to the crustacea, Diaptomus minutus and Cyclops prasinus being important elements, while the increase in Bosmina is another factor. ‘The rise the last of November is due mainly to the very large number of Bosmina, combined with large numbers of Asterionella and Sphaerella. The striking feature of the Green lake curve for the year ANNUAL DISTRIBUTION OF THE ORGANISMS. 41 1899-1900, however, is the great increase in the total plankton in February and March when the lake was covered with nearly two feet of ice. The entomostraca figuring in this maximum were Diaptomus sicilis and Bosmina. With these were asso- ciated many rotatoria. But it was to Asterionella that the great increase was mainly due. This organism was present in countless numbers. In the maximum in June Diaptomus sicilis and copepod larvae were prominent, but here again Asterionella was perhaps the most important. The maximum of the first of August, 1900, was due to several entomostraca, as in the case of the preceding year. Daphnia was less abundant than in 1899 but formed perhaps the most important factor in the larger maximum of Sept. 1. In March again occurs a winter maximum, as in 1900, but the total is much less. ‘This was caused, as the year before, mainly by the enormous increase in Asterionella, associated with great num- bers of Synedra pulchella and Synedra acus var. delicatissvma. In the summer of 1901 there was a single maximum in the latter part of July in which, as in the former years, Diaptomus minutus played a very prominent part; at this time, too, Cera- tuum and Dinobryon were very numerous. In the winter of 1902 there was again an increase as in the two preceding years caused in part by the numbers of Diapto- mus sicilis, but more by the enormous numbers of Asterionella and Synedra pulchella. COMPARISON OF AMCUNT OF PLANKTON IN DIFFERENT YEARS. It will be seen, by a glance at the curves, that the total amount of plankton varies quite widely in the years under considera- tion, and the question arises whether there may be plankton poor years and plankton rich years. Three summers would hardly give material to decide such a question, but it may be noticed that the summer production in 1901 was distinctly less in both lakes than in the preceding years. It is interesting to notice in this connection, the plankton collections made in a 49 PLANKTON OF WINNEBAGO AND GREEN LAKES. series of northern lakes about the middle of August in 1900 and 1901. Im all the lakes the collections of 1901 were much smaller than in 1900. It would seem probable then that the summer of 1901 was a plankton poor summer. I do not know what reason can be assigned for this fact. It is a somewhat significant fact, however, that the curve of mean temperature for 1901 differs distinctly from the mean in that it rises sharply to a maximum in the middle of July and then declines rapidly, instead of continuing at practically the same height through most of August as is commonly the case. It is possible that the short duration of the extreme hot weather of summer may have had some effect in reducing the amount of plankton. COMPARISON OF PLANKTON IN GREEN LAKE AND LAKE WINNEBAGO, In comparing the curves of the two lakes, perhaps the most noticeable difference is the enormously greater summer produc- tion in Lake Winnebago. This is due to the very much greater production of plants in the shallower lake. Green lake varies from the mean much less during the year than does Lake Win- nebago. The winter production in Green lake is absolutely considerably greater than in Lake Winnebago. ‘This, as has been pointed out before is due both to the greater number of entomostraca, and to the enormous production of Asterionella in Green lake, accompanied sometimes by a corresponding in- crease in the species of Synedra. I can only conjecture as to the cause of the greater winter production in Green lake, but I think it is possibly connected with the fact that it is very late before it is frozen over. Lake Winnebago, because of its slight depth, is cooled off early in the fall and is covered with ice while Green, lake is still open and exposed to aeration. The actual amount of water in Lake Winnebago is small as compared with its superficial dimensions, and its supply of oxygen must be much smaller than that of a body of deep water like Green lake: thus it seems to me that the conditions for animal life ANNUAL DISTRIBUTION OF THE ORGANISMS. 43 must be much less favorable in Lake Winnebago in winter than in Green lake. I have very little to offer in the way of proof of this suggestion ; it is significant, however, that the only other lake from which I have winter collections,—Cedar lake, Wash- ington Co.,—has an amount of plankton intermediate between Green lake and Lake Winnebago. Because of its smaller size Cedar lake must be earlier than Green lake in freezing over, and beause of its greater depth,—nearly 100 feet,—the amount of water as compared with its area is much larger than in Lake Winnebago, and we might expect a larger production of plank- ton than in that lake. COMPARISON WITH THE PLANKTON OF OTHER LAKES. The other lakes connected with the Fox river, namely Lake Poygan, Lake Wineconne, and Lake Buttes des Morts, resemble Lake Winnebago very closely in the plankton, but the amount is not so great. Of the other lakes, Pelican and Shawano were particularly rich in plankton. Shawano, at the time of one set of collections, had more plankton than Lake Winnebago. FPeli- ean, in three of the four years in which examinations were made, was considerably richer than Lake Winnebago. Both Shawano and Pelican are shallow lakes and comparable with Lake Win- nebago in their general characteristics. Sand lake in 1899 had about the same amount of plankton as Pelican, but much less in the three succeeding years. Stone, Birch, Cedar, and the Waupaca lakes may, in a general way, be classed together, all having considerably less plankton than the shallower lakes. The Eagle River lakes are connected by wide thoroughfares so that they resemble each other very closely, but the larger ones seem to have the greater amount of plankton. The same thing is true of the Waupaca chain of lakes. In the case of the large collections which were made in all these lakes, it was the plants also that formed the prominent part of the plankton. In Table IIT have been listed the volumes of plankton as ob- 44 PLANKTON Of WINNEBAGO AND GREEN LAKES. tained in the various lakes of the state. In addition to what has just been said in comparing the results with those in Green lake and Lake Winnebago, something should be said of the lakes as compared with each other. The collections on the northern lakes were made in the course of four rapid trips in four suc- cessive years. The collections of 1899 were made in the latter part of September, and those of the succeeding years about the middle of August. The collections were practically synchro- nous in each year, and a comparison of the figures is interesting, although, as I have said in another part of this paper, one must be careful about drawing inferences from a small number of collections, and it is only averages upon which one can place much reliance. | In the following table, in which I have listed the lakes of this circuit for the sake of comparison, I have placed first Birch and Stone lakes which belong distinctly to the class of small deep lakes, next Sand lake, which is intermediate between the two classes, then the Clover Leaf lakes, which, although shal- low, yet because of their small size, have a marked thermocline; the rest of the list belong distinctly to the shallow lake type. As the Eagle River lakes do not differ materially in the amount of their plankton, I have listed only one, the largest,—LHagle lake. | ~ 1899. | 1900. | 1901. 1902. Birch yey yes Glare AE een 80.97 114. 24 719.25 59.50 LOM e iy aie oes ernie rere 71.4 171.36 52.36 54 5D FeV OG ba Pa ave wae APE ORE ACIS NER Sli oi 905.16 152.32 63.43 124.95 Clover Leaf: Gold eoyrod ees eral eee eee 90.44 59.50 71.4 PANSY eraieys doe Heda stellate RENO ae Ree 114. 24 33 80 9271 Siiaimiro cena aoe ste ates sa eA a cae 107.10 35.70 232.05 JSS \ee ieee: Wea eee Mei Ie Al i aay te FINO is aca aerial ened lameenen De rsa epee ats dias: et SUVer Wy ea ee a ele eae Sear ieee (GFP hodided GHP eas eeerh| PUG re LO HH ta) Ce PD ULTIO TUNE erie ye sep ave ees a leusee toverckoonenshe MOT SEO see AL RE rt 0 |e LifoTays 7A ee a oy AIRY Oraice ESI er aa en MRR Nees Ee Mn a TSAR Regen MSSM ES Dae) Daa less aera aise aie autem ica ceanacs eu ge annie, oa uae ee 933 24 185.64 345.10 IPeli@anieae a Sie yi ae ea ane 122.09 466.48 376.04 517.65 ANNUAL DISTRIBUTION OF THE ORGANISMS. 45, When one examines this table, the degree of uniformity in successive years is somwhat surprising, for we must expect an- nual variations in the maxima of the total plankton. I have already called attention to the fact that all the collections of 1900 were larger than those of 1902. This was especially miarked in the case of Birch, Stone, and Sand lakes, and was largely due in each case to the greater number of crustacea, es- pecially of the Diaptom1; in Sand lake there was also a larger number of the algae in 1900, but it was in the crustacea that there was the greatest difference. The large collection in Shamrock in 1902 was due in the main to the comparatively large number of Daphnia pulicaria; the great size of this form makes it, when present, an impor- tant factor in the total plankton. In the distinctively shallow lakes, Eagle, Pelican, and Shawano, the uniformity in the successive years was very marked, the differences being hardly greater than might be ex- pected from hauls made on successive days in the same year. It will be noticed that the uniformity in the case of the shallow lakes is much greater than in the deep lakes. In comparing the lakes with each other at each period of col- lection we find that Pelican has the greatest amount of plank- ton in the last three years, but was outranked by Sand lake in 1899. This large amount of plankton in Sand lake in 1899 was due to the abundance of “bloom,” in which the mst prominent plant was Anabaena. I think this is an exceptional record for Anabaena for, as I have stated before, the plants of the bloom flourish especially in warm weather, and we should not expect them late in September. The time of the collection, too, had been preceded by cold weather, and on the day of the collection ice had formed by the roadside in the morning. Eagle lake was a constant second to Pelican in the years un- der examination. In regard to the other lakes there seems to be no fixed order of precedence. In comparing the years 1900 and 1901 it is interesting that 46 PLANKTON OF WINNEBAGO AND GREEN LAKES. the relative difference is much greater in the case of the deep lakes than is true of the shallow lakes. I have already remarked, in comparing the plankton of Green lake with that of Lake Winnebago, that Green lake has the greater amount of plankton in the winter, and Jake Winnebago the greater amount in the summer. I think we may say that this general comparison holds in regard to all deep and shallow lakes. ‘The deep lakes because of the later date of freezing, the larger amount of water, and hence the larger amount of available oxygen, will have a greater amount of winter plank- ton, while the shallower lakes will in summer have the greater amount of plankton because of the favorable conditions for plant growth produced by the higher temperature of the water and the relatively large area of the bottom that is reached by the sunlight. DISCUSSION OF RESULTS. 47 CHAPTER III. DISCUSSION OF RESULTS- VALUE OF PLANKTON COLLECTIONS. Tt is a little difficult to state just what value should be placed. on the measurement of plankton collections in limnology. It is, of course, evident that such collections give material for the qualitative determination of the fauna and flora, so that lakes can be compared with each other with reference to the distribution of forms. Care must be taken in this, however, unless the lakes are under examination for a long period of time, for, while in general the annual appearance of any form will be at about the same time in all lakes, nevertheless this appear- ance is subject to considerable variation, partly from differences in local conditions, and partly from differences in other condi- tions of environment; I think there is no doubt that the algae of the “bloom” may differ in their maximum periods not only days, but perhaps weeks, when the lakes appear to have similar condi- tions. Thus it may happen that a form may be abundant in one lake, and absent or present in small numbers in another at any given time, but later or earlier it may be abundant in the second lake. The absence of a form at a particular time is not always proof that the form is never present. For example, Diaptomus sicilis might easily be overlooked in the fauna of Green lake if we were to depend entirely on summer collec- tions, or Cyclops pulchellus in Lake Winnebago if no winter col- lectons were made. As has been indicated already, also, 48 PLANKTON Of WINNEBAGO AND GREEN LAKES. forms may be very abundant in one year and either entirely lacking or present in small numbers in another. So even for qualitative determinations, it is necessary, if one would be strictly accurate, to make collections not only at all seasons of the year, but for a series of years. When one makes plankton measurements, and compares one lake with another from such records, the results are valuable, but it must be recognized that they are subject to certain sources of error. It has been already indicated that the horizontal dis- tribution of the plankton is remarkably uniform. Yet this uni- formity is subject to wide variations, so that inferences from single plankton collections might be very erroneous. Safety in drawing conclusions lies only in averages, and the larger the number of collections from which those averages can be drawn the safer are the conclusions. It follows, I think, that refinements in plankton measurement are unprofitable. It must be acknowledged that the measure- ment by settling is inaccurate, and that the use of the centri- fuge, while more accurate, nevertheless still leaves a large margin of error. Of course measurement by weighing is exact, but the results hardly justify the labor necessary. I would not have it understood, from what has just been said, that I would throw discredit on plankton measurement, for this paper is evidence of the importance I attach to it, but I wish to emphasize the fact that such measurements never can have the merit of exactness, for allowance must always be made for error. It is very desirable if lakes are to be compared with each other in regard to the amount of plankton, that they should be under continuons observation for a long time, preferably for a term of years, for there may be considerable differences in the plankton of successive years. DISCUSSION OF RESULTS. 49 RELATIVE IMPORTANCE OF PLANKTON CONSTITUENTS IN PRODUCING MAXIMA. In Lake Winnebago and shallow lakes of a similar type it is evident that the great maxima are produced by plants. We have found in the discussion of the Lake Winnebago plankton that! certain cladocera, like Hurycercus, sometimes form an im- portant part of the plankton, but it may be said generally that all large maxima are dependent for their size on plants. In deep lakes of the type of Green lake, the crustacea, as com- pared with the plants, are much more abundant than in the shal- low lake, but even here, too, the plants, especially the diatoms, are to a considerable extent responsible for the maxima. This is shown very strikingly in the March maxima of Green lake. It will be noticed, too, that when crustacea are largely im+ portant in producing plankton maxima, it is not as a rule the result of the development of a single kind, but the result of the simultaneous development of several kinds. In the discussion of the total plankton of the lakes in the northern part of the state, I have stated that the August plank- ton of the shallow lakes in successive years is more uniform than that of the deep lakes. This is explained, I think, by the greater relative importance of the crustacea in the deep lakes, for there is greater variation in the maxima of the crustacea than in those of the “bloom.” In plankton collections cover ing a period of years, we may expect the curves for the shallow lakes to show much greater uniformity than those of the deep lakes because of the greater importance of the vegetable part of the plankton. COMPARISON OF PLANKTON AND TEMPERATURE CURVES. The temperature curves of the lake waters are similar to the mean curves of the localities in which the lakes are situated, with of course fewer variations and with a summer maximum at a Ponewpnat later period. The summer maximum of the sur- 50 PLANKTON OF WINNEBAGO AND GRHEN LAKES. face in Green lake ordinarily comes in the early part or middle of August, while the annual mean of this part of the state has its maximum about the middle of July. Lake Winnebago, be- cause of its slight depth, warms up more quickly and cools with corresponding quickness. In comparing the temperature curves with the total plankton curves we find only a general resemblance. The greatest amount of plankton, generally speaking, is found in the hottest months. Remembering what I have said before, that the plank- ton is largely dependent for its amount on the plants, this is what would be expected, inasmuch as a high temperature is fa- vorable to plant growth. In some cases a maximum seems to follow the period of highest temperature, but this is by no means always the case. Inasmuch as plants are more impor- tant in the plankton of the shallow lakes, it follows that the plankton of such lakes follows the temperature curve more closely than does that of the deep lakes. The deep lakes have annual conditions more closely approaching uniformity, hence the variations during the year are less marked, and as they never reach the high summer temperature of the shallow lakes, they never have such a large production of plants like Glovo- trichia, Anabaena, and Lingbya. The fact, too, that the crustacea form so much greater pro- portion of the plankton in the deep lakes, makes the correspond- ence with the temperature curve less, for some of the crustacea have winter maxima. In comparing the annual curves of the crustacea, it appears that the summer maxima of most of them came somewhat earlier in 1899 than in 1900. ‘This does not seem to be true of the general plankton. I have been interested to know what made the difference, but I am not sure that I have detected the real reason. The maxima of the general plankton, as has been said, are largely dependent on the plants rather than the ani- mals. It would seem then, that the cause which made the 1899 summer maxima of crustacea greater than those of 1900 must have been something that would affect crustacea but would not DISCUSSION OF RESULTS. aL affect plants. A comparison of the temperature curves of the two years shows that the summer maximum came somewhat earlier in 1899 than in 1900. This might explain the earlier maxima of the crustacea, but I do not quite undestand why the plants should not have been equally affected. COMPARISON OF CURVES OF TOTAL PLANKTON WITH CURVES OF PLANKTON CONSTITUENTS. As has already been noted, the curves of plant production follow very closely the curves of total plankton, for it is to plants that the great differences in the amount of plankton are due. There are some marked exceptions to this general rule, like the great maxima of certain of the diatoms. In general terms it may be said that the curves for animals also follow the total plankton curves, most of them reaching their maxima in the summer months. There are many excep- tions, however. Some of the crustacea are perennial in their occurrence, and some have winter maxima. Some of the roti- fera, too, occur only in the winter months. Generally speak- ing, it is in the deep lakes that we find more of those animals having winter maxima, although there are some exceptions. Some of the Lake Winnebago rotifera, for instance, are found only in the winter season. It is evident, however, that the greater uniformity of conditions in the deep lakes would make winter production more possible. HORIZONTAL DISTRIBUTION, One of the questions to which especial attention was paid was the matter of the uniformity of horizontal distribution. I diseussed this question in some detail in a former paper (Marsh ’97, pp. 218-223) expressing my own. belief that the numbers of crustacea might vary widely in different parts of a lake, and that they might, at some times, be aggregated to- 59 PLANKTON OF WINNEBAGO AND GRHEN LAKES. gether in swarms, but I did not attempt to explain the reason of the existence of swarms. I also stated my belief that single plankton collections might give erroneous impressions, and that an accurate measure of plankton could only be obtained by averaging a considerable number of collections. . ee Reighard (Reighard ’98) acknowledges the wage o distribution of the individual constituents of the plankton. Yung (Yung ’99), as the result of his studies on the plankton of Lake Leman, states positively that the horizontal distribution varies within wide limits and that there is no doubt of the ex- istence of aggregations of organisms in certain localities. ‘The causes of these aggregations he states are diverse, but intimates that sometimes currents may accomplish this. Steuer (Steuer ’01) states that in his opinion there is no further call for discussion, but that it must be admitted that under similar physical conditions thers will be uniformity in horizontal distribution. He does not, however, give the reasons for this opinion. While I felt quite sure that my position on the question was, in the main, correct, it Seemed to me desirable to make a con- siderable number of collections to test the correctness of my statement in a somewhat conclusive way. Two questions presented themselves for solution. First, the comparative amounts of the plankton at different parts of the lake at any given time. Second, if it was proved that there was a difference in horizontal distribution, is this a fairly con- stant difference between any two localities, or is it one that may vary from day to day or from hour to hour? To answer the first question, at several times collections were made at a considerable number of locations on the same day. The following table will show the results. In preparing this table, I have listed no collections where less than four locations were tested. In most cases the figures for the plankton were {ne average of three collections. DISCUSSION OF RESULTS. 53 Tuble showiag comparative amounts of plankton at different parts of the lakes at given times. Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Laks Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lake Lako Name of Lake. Wianebago..... Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago eee ee ww ee eee Ce ee sewer ee ee ec eee see ee eee we te oe CC Cy eee ee tees tee a ee er re ee cone Winnebago.... Winnebago Winnebago CC Winnebago...... Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago Winnebago WInnebago Winnebago Winnebago Winnebago Winnebago ee ee ee) eee eo wees Powe ee Cry Se ee ee eee eo ee ewes ee ey re ee Lake Lake Lake Buttes des Morts....... Buttes des Morts....... Buttes des Morts Lake Buttes des Morts....... Lake Buttes des Morts....... Lake Buttes des Morts....... Cedar lake, Washington Co... Cedar lake, Washington Co... Cedar lake, Washington Co.. Cedar lake, Washington Co.. Cedar lake, Washington Co.. se ewer Date. Amount of Piank- | Coll. No. ten. 142 8 99.22 154.7 99 24 59.5 99 25 101 15 99.27 83.3 99.28 41 65 89.3 62.48 99.31 59.5 GQ 39 107.1 | 99.33 1309 | 99.62 107 | 69.65 172.55 GS 66 163.74 99.65 139.94 S967 72, 83 69.68 119. 99.69 245.85 99 87 206.11 99.88 333 2 99.89 130.9 99.90 144.70 99 91 126 85 69.92 904.85 ©9 118 226.1 99.122 194 45 99,124 261.8 99.195 924 2 99.126 130.9 99.160 83.3 99.161 124.95 99 162 91.15 69.163 166 6 99.223 154.7 99.294 154 7 99 224 154.7 89 226 130.9 99 .228 190.4 59.229 95.2 99 .230 66.64 99 231 107.1 99 232 130 9 99 233 114 24 99 234 59 5 99 235 124.95 99 154 119. 99.155 130 9 99.155 130.9 99.158 130 9 99,159 54 PLANKTON OF WINNEBAGO AND GREEN LAKES. Table showing comparative amounts of plankton at different parts of the lakes at given times—continued. Amount Name of Lake. Date. of Plank- | Coll. No. : ton. 1900 Cedar lake, Washington Co...| Mar. 24........... 57.6 0.16 Cedar lake, Washington Co...| Mar. 24........... 59.5 0.17 Cedar lake, Washington Co...) Mar. 24........... 90.44 0.18 Cedar lake, Washington Co...} Mar. 24........... 83.3 0.19 Cedar lake, Washington Co...| Mar. 24........... 71.4 0.20 Cedar lake, Washington Co...| Mar. 24........... 59.5 0.21 Cedar lake, Washington Co...| Mar. ee beau Sac 9.52 0.22 1 ake vRoyecant se o5 552 ce ene anlysnarier sacs 111 15 99.93 hake Royeansec. ss 6 eee daly) Od. eee eee 85.20 99.96 hake Poy ean io. essere DULY aes cise ele 87.35 99.97 IbakesBoyeane 022 cee PANG Oe 2b wees 81.40 99.98 Make Poy canes. 2e cin heal ely) aoe weeiee see 107.1 99.99 MakeiPoyean nse. @ auee soces nally parses eer Ie Ts 99.100 Make Poycanisi5) 26... sees een AUG Oe janet toe 123.76 99.166 akey Poy ean icc. cece seas ING Geena 95.2 * | 99.168 WakevPoyean: is. cece oasis se PAU Oe Ste cae: 23.8 99.169 .- Make (Poy gan soe esa ells PERO SL Sanaa ce 62.36 99.170 Make) Moy ran i. cones cae AVOCA SiGe ae rne ns 95.2 99.171 ake Poy oan. 610 65 eien say neceallls pA an) GOR meratene otetere 92.34 99.172 hakewoyoansaseenee aeieeeicene AULT RS Gas eg ee 53.55 99.173 Lake Winneconne ............ Pai Youen soy Nana eres 95.2 99.176 Lake Winneconne............ ANI Se GOintia across 89.25 99.177 Lake Winneconne............ IAUSS OMS ania eae 86.28 99.178 Lake Winneconne............ AU Gites a aalecciaia 81.33 99.179 Lake Winneconne............ AIRS Gia ae aera, 107.1 99.180 Lake Winneconne ............ JN Vea 0 Seager 110.08 99.181 Lake Winneconne ............ nally 24 eas 101.15 99.109 Lake Winneconne............ Otis Dae ee cece 130.9 99.110 Lake Winneconne............ ly 2a ee aaa 117.10 99.111 Lake Winneconne............ anally DE a Ne eine 114.24 99.112 Lake Winneconne............ Oily D4 Oe ew axe 112.57 99.113 Shawano dake 230 ne seis aces WANTS SBR er venice 119. 99.186 Shawanoilake %.22 seece secs oe ASS SBA eee oe 130.9 99.187 Shawano lakes 3 P ee le MIKE SHG obo OCA 249.9 99.188 DHAWANO AKG io!) 20/2). senseless AU ORS a eS arate 220.15 99.189 DISCUSSION OF RESULTS. 55 The stations where these collections were made were chosen much at random, with the exception of those in Cedar lake, which were for the most part in the limnetic region. In many eases the stations of a given date were widely separated. In lakes Poygan and Winneconne they were scattered from one end of the lake to the other. In Lake Winnebago most of them were within two or three miles of the laboratory at Stony Beach. The route traversed on July 18, however, must have covered 16 or 18 miles. In looking over the table, the amount of uniformity is cer- tainly very striking. This is especially true of the collections in Cedar lake on Aug. 4, 1899, when five collections varied only from 119 to 130.9. These collections were all made in the lim- netic region, and the depths at the different stations did not vary greatly. The collections made in Cedar lake on March 24, 1900, were made through the ice, and the depth at the different stations varied from six meters to thirty-one meters. Collections 0.18, 0.19, and 0.20 were made at a depth of thirty-one meters, the depths at the other stations being as follows: 0.16 thirty meters, 0.17 twelve, and 0.22 six. There would seem in these collections to be a connection between the depth and the amount of plank- ton. This. is perhaps, as would be expected, for the tempera- ture conditions in winter are practically uniform for all depths, and as temperature is one of the most important factors lmit- ing distribution we might infer that increasing depth, under such conditions, would tend to increase the amount of plankton. Winter collections made on Green lake at other dates, not listed in the foregoing table, seem to confirm this generalization that during the winter months in a deep lake the amount of plankton varies, in a general way, with the depth. These facts in regard to the winter plankton led me to look over my notes to see whether there was evidence of any similar difference in the summer. My only available collections for this purpose were those made on Green lake, for the collections from Lake Winnebago were nearly all taken from what was 56 PLANKTON OF WINNEBAGO AND GREEN LAKES. practically a uniform depth, and the collections from other lakes were not numerous enough to have much bearing on the question; it is interesting to notice, however, that in collections made in Birch lake in September, 1899, and August, 1900, which were made at different depths, the amount of plankton varied with the depth. It appears from the Green lake collec tions that there is a distinct relation between the depth and the plankton, the amount of plankton increasing with the depth, but this difference is much less marked in summer than in 5B winter. I do not remember to have seen any statements by other authors of the effect of depth on plankton. It is known, of ae course, that there is a difference in amount between littoral and _limnetie plankton, but I think it is without doubt true, that in the limnetic plankton, depth is a factor in distribution, the variation in accordance wiih depth being most clearly marked in the winter. It does not follow, of course, that the deeper lakes necessarily have the greater amount of plankton—this certainly is not true, but simply that depth, in any given lake, is a factor to be considered in horizontal distribution. In the collections from Lake Winneconne, the uniform- ity is very marked. In this case the collections were made at different locations over the lake, and may be considered as typical of the whole lake. This is true in this lake, however, that the conditions vary little in different parts of the lake, and we would expect greater uniformity. In Lake Poygan the conditions are much as in Lake Winne- eonne, both lakes being expansions of the Fox river: it is shal- low, the depth varying but little, with low swampy shores. We should expect, of course, a somewhat different fauna and flora in the weeds alongshore from that existing in the limnetic re- gion. But in the limnetie region, where the collections were taken, the winds and the currents must produce all the changes in environment. While the plankton differed more in Poygan than in Winneconne, yet, if we throw out 99.169, the variation is not very great. This collection was made in a place sur- DISCUSSION OF RESULTS. 57 vounded by weeds, and it was noted at the time of the collection that the water was remarkably clear, although in most parts of the lake it was quite opaque because of the presence of vegetable matter. In Shawano lake the variation was somewhat greater than in Winneconne and Poygan. Shawano varies more in its depths, but otherwise the conditions are much as in other lakes. It was from the collections made on Lake Winnebago, how- ever, that I hoped for the most conclusive results. These were made in considerable numbers and at such widely separated lo- ealities that it seemed to me it would be a fair test of the uni- formity of horizontal distribution. I have placed in the foregoing table the amounts of plankton obtained in Lake Winnebago on seven different days when col- lections were made at several locations. The amount of uni- formity is certainly very remarkable, and was, I must confess, somewhat disheartening to me, for I had a theory to maintain. The variation does not, in any ease, exceed the limits which Hensen says are compatible with uniformity, as he defines the term. In former papers (Marsh ’97, and Marsh 701), I have dis- cussed this subject in detail, but the results of these collections in Lake Winnebago and adjoining waters have led me to medify somewhat the opinions then expressed, although I think they were, in the main, correct. There seems to be no question that in Lake Winnebago the horizontal distribution of the plankton is practically uniform. How then can I explain the results of collections as given in my former paper (Marsh 797)? In the former paper I was discussing only crustacea, and came to the conclusion that some of them were at times present in aggregations which might be called swarms. These agerega- tions have been noticed by other observers, as for example Birge (Birge ’97, 371). I acknowledge now that I have, in the past, attached too much importance to erustacea as an element in the plankton. As will be shown later, the controlling element in the amount of ; (Ab) cre TY , 4 Pena) 5) ; 4 ot Vales We cd ee, Caer ead thd tx q pt se ak SEs k f 4. L \“t , by. a ; Me ay yA Pry Wi PY , reat t) KAtaeALe 1 He ad fit. ile LENS WY ‘4 LAA AASAMA 4 aE Anf KL ‘ pal § | yaaa x 58 PLANKTON OF WINNEBAGO AND GREEN LAKES. plankton is the vegetable material. This is especially true in shallow lakes in which the crustacea form: relatively a much smaller part of the plankton than they do in the deep lakes. The conclusicns which I reached in my former papers were very largely derived from work on Green lake, in which the erus- tacea are more abundant than in Lake Winnebago, not only rel- atively to the vegetable organisms, but absolutely. It would follow that aggregations of crustacea would affect the total plankton much more in the deep lakes. In lakes like Lake Winnebago crustacea seldom form a controlling part of the plankton except when large numbers of certain of the cladocera are present, and then the total may be appreciably affected. For instance, in the collections listed for July 10, 799, the larger totals were caused by the presence of Hurycercus which was present in unusual numbers, and the evidence from my col- lections seems to show that Hurycercus occurs in moving aggre- gations or swarms that perhaps move under the influence of slow currents. The collections from the deeper lakes, like Green lake and Stone lake, show greater differences when taken on the same day at different localities than do the collections from shallow lakes. In, these deeper lakes the crustacea form! a larger pro- portion of the plankton. My conclusions then are as follows: 1. I must acknowledge that the uniformity of horizontal dis- tribution is greater than I had formerly supposed. 2. Variations in uniformity, when general conditions remain the same, are largely due to variations in the numbers of crus- tacea. 3. Inasmuch as crustacea in deep water lakes are not only more abundant relatively to the plants, but are absolutely more numerous, it follows that the horizontal distribution of the plankton in deep water lakes will be less uniform than in shal- low water lakes. Large variations in the horizontal distribution of the plankton in shallow lakes will only be noticed, under ordi- nary conditions, when, for some reason, there is a local aggre- DISCUSSION OF RESULTS. 59 gation of some of the larger cladocera, such as Daphnia or Eurycercus. 4, In winter the horizontal distribution of plankton in deep water lakes will bear a more or less close relation to the depth. This is explained by the fact that temperature is one of the most important factors in the control of the distribution of the plankton, and in winter the uniform temperature of the whole depth of water makes possible a larger production of plankton in deep water than in shallow. COMPARISON OF PLANKTON COLLECTIONS OVER MUDDY AND STONY BOTTOMS. As intimated earlier in this paper, in the regular collections on Lake Winnebago, one series was made over the muddy bot- tom, well out in the lake, and another over the stony bottom nearer shore. The average of the collections made in the summer of 1899, when they were made daily through the raonths of July and August, seems to show that the collections over the muddy bottom were decidedly larger than those over the stony bottom. This difference may be explained by the different effect of the character of the bottom! on the plankton, or by the effect of the slight difference in depth. I have shown elsewhere that the depth has an influence on the amount of plankton, and it is entirely conceivable that in the averages of a large number of collections, a difference of a meter or so in depth may have had a marked effect on the amount. JInas- much as the greatest depth at which collections were taken was only about five meters, a difference of a meter would mean a difference of twenty per cent., which might have a decided in- fluence on the amount of plankton. I am, therefore, inclined to explain the difference between the muddy bottom) and the stony bottom as due rather to the difference in depth than to the dif- ference in the character of the bottom. G60 PLANKTON OF WINNEBAGO AND GREEN LAKES. CHAPTER IV. DISTRIBUTION OF SPECIES. GEOGRAPITICAL DISTRIBUTION. The ease with which plankton forms can be carried from place to place makes it unlikely that any lake will have a pecu- liar fauna or flora. The agencies by which this distribution is brought about have been fully discussed in other papers. Except, then, as the physical conditions are distinctly differ- ent, we should expect uniformity rather than diversity. As has been intimated already, there is a distinct difference be- tween the constituents of the plan..ion cf the Great Lakes and of smaller bodies of water, and in the smaller bodies there is a marked difference between the deep lakes and the shallow lakes. I have already discussed the distribution of Cyclops brevispi- nosus and Cyclops pulchellus, the first, as a rule, being confined to the shallow lakes and the latter to the deep ones. Diaptomus oregonensis is common to all the shallow lakes. Diaptomus minutus is not found in Lake Winnebago and the lakes immediately connected with it; it oceurs in the deep lakes, but is not strictly confined to them, as it may be found in others, especially in those that are further north. Cedar lake, Washington county, is peculiar in being the only lake in the state in which I have found Diaptomus sicilozdes. This is common in the states to the south and west of us, and it seems probable that it may be found in other lakes in Wis- consin. Pelican lake is, I believe, the only lake of any size, which does not have large numbers of Diaptomus. I made a large num- DISTRIBUTION OF SPECIES. 6t ber of collections at different times without finding a single specimen of this genus, and I had concluded that it was en- tirely absent from the lake, but in 1900 I found two or three individuals. This absence of Diaptomus is one of the most pecu- liar facts in distribution which I have run across. Pelican lake is a large body of water, with a maximum depth of about twelve and a half meters and with a large amount of plankton. It is considered a fine fishing lake, and one would expect an abundance of the ordinary crustacea of the plankton. In the collections on the northern lakes work was carried on in two distinct drainage areas and I was interested to see whether any difference in the faunae and florae of the two areas could be detected. As I expected, there was no difference ex- cept that due to the difference in depth and general physical conditions of particular lakes. Generally speaking, the result of these collections was to con- firm the statements made by other authors and myself that there is practical uniformity in the fauna and flora of lakes over wide extents of territory, except as differences in depth produce con- ditions of especial character. It is strange, however, that with this general uniformity there should be cases of isolation like that of Diaptomus sicilordes in Cedar lake or of failure of oc currence like the lack of Diaptomus in Pelican lake. In the discussion of the means by which organisms are dis- tributed from lake to lake I am inclined to think that too much importance has been attached to the work of water fowl. While, doubtless, it is a proven fact that water fowl carry organisms, seeds, and eggs, from lake to lake, I imagine this is a very minor factor in distribution. It is a fact that communicating bodies of water are pretty certain to have the same fauna and flora. This is very noticeable in the lakes in Michigan which are connected with Lake Michigan, for their faunae are iden- tical with that of the larger lake. The same is true of Lake Winnebago and its connecting waters. When lakes are pretty distinctly separated from each other, there is likely to be a dif- ference in fauna and flora. In other words “isolation” plays: 62 PLANKTON OF WINNEBAGO AND GREEN LAKES. a large part in producing differences in lake faunae. The chance planting of certain forms may determine the character of the fauna for a long period. Everything in Green lake would seem, to favor the growth of Cyclops pulchellus as the limnetic form of Cyclops. That it does not exist there, it seems to me, must be simply because it has not been planted, and there is no way it can reach that lake except through the agency of water-fowl. Diaptomus siciloides in some way got a foothold in Cedar lake, and remains there because of its isolation and is not carried to other lakes, because there are not suitable connect- ing bodies of water. I have noted in a former paper (Marsh 795), that: Diaptomus Reighardi was found only in a few lakes in the northern part of the southern peninsula of Michigan. If water-fowl readily carried entomostraca from one body of water to another, it would seem very strange that this species should not appear in the lakes in northern Wisconsin, instead of being confined to such a narrow habitat. It is noticeable, too, that Diaptomus Retghardt in Michigan is, for the most part, found in lakes closely connected with each other. It appears, then, that isolation caused by the physical con- figuration of the country will tend to produce distinct differ- ences in plankton constituents, in spite of the other causes which may be at work to distribute animals and plants. COMPARISON OF THE FAUNAE AND FLORAE OF DIFFERENT CLASSES OF LAKES. The preceding subject leads naturally to the question of the faunal and floral distinctions between the different classes of lakes. The classification, as made in the earlier part of this paper, was based on physical distinctions which must affect the environment and produce characteristic differences in the animals and plants. As a matter of fact it was such differences which first led me to suggest the division of lakes into deep and shallow. DISTRIBUTION OF SPECIES. 63 In the discussion of the annual occurrence of the various or- ganisms, these differences have already been noticed in detail, but it may be well to present them in a summarized form, In the ease of plants the distinction between the different classes of lakes is more quantitative than qualitative, for the lit- toral conditions of deep lakes are such as to permit a great variety of forms, although they do not allow any large multipli- cation of numbers. So that while the plant production in the shallow lakes is vastly more prominent than in the deep lakes, most of the species of the shallow lakes can be found in greater or less numbers in the deep lakes. Clathrocystis and allied forms, and Oscillaria, however, may be considered peculiar to shallow lakes. Glovotrichia, too, is a shallow lake form, but not exclusively so, as it occasionally occurs in large numbers in a deep lake. Anabaena is the ordinary form of the “bloom” of the deep lakes but it is not peculiar to them, but is even more abundant in the shallow lakes. Of the protozoa, Ceratiwm is character- istic of the deep lakes. It occurs in shallow lakes, but in lm- ited numbers. I do not find that Dinobryon can be considered as characteristic of any class of lakes, although European, au- thors have made the distinction between Chrodcoccaceae and Dinobryon lakes. So far as our Wisconsin lakes are concerned, Dinobryon can not be said to be characteristic of any class of lakes. Of the rotifers, Notholca longispma, while found in both classes of lakes, is found characteristically in the deep lakes; there it is common and sometimes in great numbers. Conochilus, while not found in all shallow lakes, seems, never- theless, to be pretty well confined to this type. Of the other rotifers, it can hardly be said that they are characteristic of either class of lakes. Of the Diaptomi, D. sicilis belongs distinctly to the large deep takes although it may be found as a migrant in some of the Michigan lakes, connected with the Great Lakes. D. minutus belongs to the large deep lakes but not exclusively so, for in northern Wisconsin and northern Michigan it may be found in 64 PLANKTON OF WIN? NEB EGO AND GREEN LAKES. some of the shallow lakes. D. sree has never been found outside the Great Lakes, and certain bodies of water immedi- ately connected with them. WD. oregonensis is typical of the shallow lakes, but occurs in some lakes that would naturally be elassed with the deep lakes, hke Lake Mendota. Epischura lacustris is not confined to any class of lakes, but: is more common in the deep lakes. Limnocalanus macrurus is found only in the large deep lakes. Of the lakes within the limits of Wisconsin, only Green lake: and Lake Geneva seem to furnish the necessary environment of low temperature with a certain amount of circulation. I have already discussed the distribution of Cyclops brevi- spinosus and Cyclops pulchellus. Of the species of Cyclops, C. pulchellus is, generally speaking, characteristic of the deep lakes. The other species are common to both classes of lakes. C. brevispinosus, C. pulchellus, and C. prasinus are limnetic in habit, C. Leuckarta is common to both the limnetiec and the lit- toral regions, while C. fuscus, C. albidus, and C. serrulatus are littoral species. Of the cladocera, Leptodora, Daphna hyalina, Bosmina,. Diaphanosoma, and Chydorus are common to all classes of lakes, but Bosmina is much more numerous in the deep lakes, and Leptodora and Diaphanosoma are found in greater num- bers in the larger lakes. Daphnia pulicaria is found for the most part in the small deep lakes, while Hurycercus, which oc- curs in such numbers in the plankton of Lake Winnebago, is. never found in the limnetic collections of the deep lakes. Peculiar to the abyssal fauna of Green lake are Mysis and Pontoporeia which are also abundant in the abyssal fauna of the Great Lakes. To sum up, while most of the constituents of the plankton are common to all classes of lakes, some few species are confined strictly to one class of lakes, while some of the others may be considered characteristic of one class, although found in small numbers in other classes. The following may be considered characteristic of the deep lakes: Ceratium, Notholca longi- DISTRIBUTION OF SPECIES. 65 spina, Diaptomus sicilis, Cyclops pulcheilus. Peculiar to the large deep lakes are Iamnocalanus macrurus, Mysis, and Pon- toporeia, all being forms favored by the deep water conditions of the lakes of this class. Diaptomus Ashland should be added to the forms found only in large deep lakes, although it is not common to all large deep lakes, but is peculiar to the Great Lakes. Daphnia pulicaria may, I think, be considered a distinctive form of the small lakes, although sometimes found in lakes that perhaps would not fall in this class. The following may be considered as distinctively shallow lake forms: Clathrocystis, Oscillaria, Diaptomus oregonensis, and, perhaps, Hurycercus. The cladocera are much more abun- dant both in numbers and in species in the shallow lakes than in the deep lakes, but the forms are not peculiar, as they are generally littoral forms which have become limnetic in the lakes where the littoral and limnetic environments are very similar. COMPARISON OF PLANKTON OF SUCCESSIVE YEARS. It is evident that the plankton varies greatly in one year as compared with another, and that the variation has uo immedi- ate connection, in many cases, with differences in annual tem- perature. I take it that the variations may be explained by the relations of the organisms to each other. It has been a favorite notion of many biologists, in which I have shared, that the balance of life in a lake undisturbed by man is maintained with a good degree of exactness; that the animal production is based, in amount, on the plant production, and that the number of predaceous animals is conditioned on the numbers of the animals that serve as their prey. It would follow, of course, that in a lake where there were great possi- bilities in the way of plant growth, there would be a correspond- ingly large number of animals. From this has arisen the com- mon inference that it is the shallow lakes, in which the amount of vegetation is greatest, that are the best for the production of 5 66 PLANKTON OF WINNEBAGO AND GREEN LAKES. fish. It has also been inferred,—lI have made the statement myself,—that inasmuch as in a state of nature there must be brought about an equilibrium between plant and animal growth, it is possible that man in his work of fish planting may disturb this equilibrium so as to interfere with the highest productive- ness of a lake; for it seems apparent that if an equilibrium be- tween plants and animals is once established, the introduction of any considerable number of either plant-eating or predaceous animals would bring in an element that would disturb nature’s balance. The result of my work on these lakes leads me to think that this idea is very far from correct. Of course, it is true that in the long run a balance will be reached, but there may be wide swings of the pendulum on either side of this con- dition of equilibrium. It is evident that the maxima, under similar conditions of light and temperature, are not reached at the same time in different years, nor is the annual rotation of forms the same in different years. Some animals, according to Birge, seem to have biennial periodicity, but others, in which this is certainly not the case, appear in great numbers in some years and not in others. There is great variability in the an- nual records of a lake. It is apparent that certain forms, un- der favorable conditions,—conditions which it is frequently im- possible to define,—seem to get such a start in the competition of life that they are produced in great numbers in some years, while in others they may hardly appear. Some animals, if the expression may be used, seem at times to get a momentum which carries them on to great production. When one stops to think of it this is no more than would be expected. Just as weeds overrun a farm, so certain forms of aquatic vegetation may, overtop everything else in a given year’s production. The con- dition of a lake cannot be compared with that of a forest un- touched by man, for in the forest the vegetation is largely per- ennial, while in the lake the vegetation disappears each year, and in the annual reappearance it is conceivable that some form, from some little changes in the environment, may get a start that will shut off other forms. Thus, in spite of the fact that DISTRIBUTION OF SPECIES. 67 the conditions of water are more stable than those of the land, there will be, in some ways, greater variability in the annual productiveness of the water. The changes in the vegetation will have a greater or less influence in controlling the animals, but in some eases, the animals seem to grow almost independ- ently of the plants. Examples of this apparently erratic production are seen in the comparison of the Gloiotrichia curves in Lake Winnebago in the summers of 1899 and 1900, and in animals in the Diap- tomus curve of 1901 in Lake Winnebago as compared with that of the preceding years, or the Diaphanosoma curve of 1899 as compared with the succeeding years. Tt is apparent that the balance of life is maintained much more evenly in deep lakes than in those that are shallower. It is to be noticed, too, that in the shallow lakes there is al- ways an overproduction of plants in the summer as compared with the animals. This has been remarked by many other authors. The overproduction becomes so great at some times in mid-summer that the water through the decay of the plants may become actually poisonous to the fish. i RELATIVE VALUE OF DEEP AND SHALLOW LAKES FOR THE PRO- DUCTION OF FISH. If lakes are to be ranked for fish production in accordance with their amount of plankton, the shallow lakes must be con- sidered vastly the most valuable. As has been stated before, this is generally considered to be the fact. It seems to me, how- ever, that this difference, if it exists, has been much overstated. Fish are dependent for their food, for the most part, on the animal part of the plankton, not on the plants. It is the ento- mostraca that furnish the basis of food for fishes. Now, in Greer: lake the entomostraca are not only more numerous than in Lake Winnebago relatively to the plants, but are also abso- Intely more numerous. They are at least as numerous in the summer, and during the winter there is a considerable produc- 68 PLANKTON OF WINNG@BAGO AND GREEN LAKES. tion when they have almost disappeared in Lake Winnebago. May it not be, then, that Green lake may have as much of that part of the plankton that is useful for food for fishes as Lake Winnebago? I have not facts, from my study of Wisconsin lakes, to prove this, but it seems to me to be at least a reasonable conjecture. It is a somewhat significant fact to me that Stone lake is considered one of the best fishing lakes in the northern part of this state, and it is one of the deeper lakes, being nearly eighty feet in depth. It is true that Green lake is not a par- ticularly good lake for fishing at the present time, but this is probably because it is, to a considerable extent, “fished out.” There is doubtless a difference between large and small deep lakes in favor of the larger lake in productiveness. As I indi- cated in a former paper (Marsh, ’97, p. 180), this may be ex- plained by the more complete stagnation in the abyssal waters of the small deep lake. In the larger lake, in which the winds have better play, the waters are piled up by the prevailing winds at one end of the lake and return, in part, at least, by bottom currents, thus aerating to some extent the abyssal re- gions. This may explain the productiveness of Stone lake, for it is a long, narrow body of water extending in a direction from north to south and frequently violently disturbed by southwest winds which prevail in this location. It is probable that its abyssal regions are much less stagnant than, for instance, those of the Chain o’ Lakes which are still deeper, but smaller, and surrounded by elevations which cut off the wind. I do not think it probable that, under similarly favorable conditions, deep lakes are ever as productive as the shallower ones, but I think the difference between the two has been much exagger- ated. In a deep lake the littoral, limnetic, and abyssal regions are quite sharply distinguished. There is, of course, no distinct dividing line between the littoral and limnetic regions, and the organisms of one may be found in the other, and yet the differ- ence between the fauna of the central regions of a lake and its shore is very marked. In a very shallow lake there is no true DISTRIBUTION OF SPECIES. 69 abyssal fauna, and in a pool the distinction between the limnetic and littoral regions is lost. In Lake Winnebago, as I have indicated in a former paper (Marsh 799, p. 181), in spite of its great size there is an inter- mingling of littoral and limnetic forms. Cladocera like Hury- cercus which are ordinarily considered strictly littoral are com- mon in the limnetic regions, and, on the other hand, limnetic forms like Diaptomus and the limnetic species of Cyclops may be found in the littoral region. In this lack of distinction be- tween the limnetie and littoral forms, Lake Winnebago is like an enormously overgrown puddle. "0 PLANKTON Ox WiNNEBAGO AND GREEN LAKES. ; LIST OF PAPERS QUOTED. ApstrIn, ’96. Das Siisswasserplankton; Methode und Resul- tate der quantitativen Untersuchung. ©. Apstein. Kiel und Leipzig. Biren. 97. Plankton Studies on Lake Mendota. II. The crustacea of the plankton, July, 1894-Dec.,, 1896. E. A. Birge. Trans. Wis. Acad. Vol. XI, pp. 274-448. Burcxuarpt, ’00. Quantitative Studien tiber das Zooplank- ton des Vierwaldstittersees. G. Burckhardt. Mittheil. der Naturforschenden Gesellschaft Luzern. 3 Heft. Fric unp Vavra, 794. Untersuchungen tiber die Fauna der Gewiisser Bohmens. Fric und Vavra. Achiv der natur- wissenschaftlichen Landesdurchforschung von Bohmen. DX Band. INre. 2: Koro, 97. On Some Important Sources of Error in the Plankton Method. C. A. Kofoid. Sci. N. S., Vol. VI, pp. 829-832. Marsu, 795. On the Cyclopidae and Calanidae of Lake St. Clair, Lake Michigan, and certain of the inland lakes of Michigan. C.D. Marsh. Bull. Mich. Fish.Com. No. 5. Marsu, 797. The Limnetic Crustacea of Green Lake. ©. D. Marsh. Trans. Wis. Acad., Vol. XI, pp. 189-224. Marsu, 799. The Plankton of Fresh Water Lakes. ©. D. Marsh. ‘Trans. Wis. Acad., Vol. XIII, pp. 163-187. Retewarp, 798. Methods of Plankton Investigation in their Relation to Practical Problems. J. Reighard. Bull. U. S. Fish Com., Vol. XVII, pp. 169-175. Settco, U. Scurorper, 700. Untersuchungen in den Stuhmer Seen. Nebst einem Anhang; das Pflanzenplankton preussischer Seeen. A. Seligo u. B. Schroeder. Danzig. Srevr, 701. Die Entomostrakenfauna der “alten Donau”’ bei Wien. Adolph Steur. Zoolog. Jahrb. XV Band, Heft. LIST OF PAPHRS QUOTED. "1 Voter, 702. EHinige Ergebnisse aus den Untersuchungen ost- holsteinischer Seen. Max Voigt. Forschungsber. aus der Biolog. Station zu Plén. pp. 47-61. Warp, 795. A New Method for the Quantitative Determina- tion of Plankton Hauls. H.B. Ward. Proc. Amer. Mic. Soc., Vol. XVII, pp. 255-260. Wutrerte, 794. Some Observations on the Growth of Diatoms in Surface Waters. G. C. Whipple. Technology Quar- terly, Vol. VII, pp. 214-231. Yune, 799. Des Variations Quantitatives du Plankton dans le Lac Leman. E. Yung. Arch. Sci. Phys. et Nat. Genéve. T. VIII, p. 344-864. APPENDIX. APPENDIX. 73 TasiE I.—Record of total volumes of plankton per square meter in Green lake. These statistics are of limnetic plankton, more than one collection was made at a given date. averages being made when Vol. in Date. ccm. 1899. suly 16... 38.67 Sulyeol 3)! 103.29 AMIS ZO as 34.75 Sept. 18.... 35.7 Oct: 65.45 Ochi gear: 57.6 Oct Ble o.: 43 .55 INKoniy (PRG ese 71.4 1900 digi, Wssec 50.69 Jans 20n2.. 65.45 Hebeavance: 197 .54 Marie 22eeee i 1Otn 54: Apr. 20.... 95.2 May 55...) 107.1 Mayr abe...) 12281 June 2....| 226.1 June 16....} 3899.84 Date. ‘Olt eo. a eae se, (a Oe Vol. in ccm. 181.36 71.4 104.72 64.26 142.8 53.55 51.65 53.55 49.98 47.6 47.6 35.7 19.01 33.8 53.55 54.74 73.78 Sept. 12... Sept. 18... "4 PLANKTON OF WINNEBAGO AND GREEN LAKES. TasLe II.—Record of total volumes of plankton per square meter in Lake Winnebago. Statistics prepared as for Green lake. Vol. in Vol, in Vol. in Date. Bee Date. wana Date. cana 1899 1899 1900 July 5 71.4 Aug. 11. 124.95 Aug. 22 316.55 July 6 71.4 Aug. 12. 90.20 Sept. 8 523.6 July 7 119. Aug. 14. 147.32 Sept. 22 152.12 July 8 111.15 Aug. 15 133.76 Oct 99.01 July 10 108 .29 Aug. 16 116.38 Oct. 20 66.64 July 11 67.69 Aug. 17 111.038 Nov. 6 40.46 July 12 136.85 Aug. 19 120.19 Nov. 21 18.8 July 13 86.28 Aug. 21 128 .52 Dec. 5 6.48 July 14 111.79 Aug. 22 158.51 1901 July 15 116.86 Aug. 26 144.22 Jan. 5 8.92 July 17 124.24 Aug. 28 83.30 Jan. 19 7.26 July 18 136.6] Aug. 30 176.12 Feb. 2 11.30 July 19 137.92 Aug. 31 95.2 Feb. 16 9.52 July 20 183.26 Sept. 16 368.9 Mar. 2 17.13 July 21 268 70 Och k 92.82 Mar. 16 8.33 July 22 191.83 Oct. 21 162.55 Mar. 30 6.54 July 25 138 .04 Nov. 4 99.92 Apr. 13 8.57 July 26 162.75 Noy. 25 59.98 Apr. 27 16.94 July 27 220.39 1900 May 11 35.22 July 28 210.63 Jan. 1 33 32 June 8 29.75 July 29 232.53 Jan. 27 65.17 June 25 42.84 July 30....| 193.26 Feb. 17.... 10. July 12....| 172.55 July 31....| 239.19 Man ni3 0 10.47 July 27... | 233. ANE Nei 173.5 WIENR Ne 66 7.38 Aug. 24 99.72 Aug. 2 146.61 Mar. 27.. 20.94 Sept. 13...., 127.09 Aug. 3 194.92 Apr. 28.. 46.65 Sept. 28 79.73 Aug. 4 107.58 May i11.. 78.30 Oct. 12 32.74 Aug. 5 101.15 May 24.. 180.40 Nov. 2 83.3 iNytres 7 138.75 June 9Q.. 202.3 Nov. 16 23.8 Aug. 8 138.75 June 25.. 128.5 1902 Aug. 9 114.95 July 9... 138 .04 Aug. 16 204.68 Aug. 10 170.41 July 28.. 145.11 Sept. 2 123.76 APPENDIX. 75 TasueE III.— Record of total volumes of plankton per square meter in various Wisconsin lakes. Name of Lake. ISIEIS) Sod oe O GOOD Co IC CHE Cone aoe aaon Sept [SuHCION aR OIG ORS EO ere SACI IERE NE ERISA Sept SIT tee clan aicrarneeivepoheimectie ele taee clalenctenencins ere Aug JE YIRELE Qt oes SIA a Ate B oe nA RP Aug ERED EU ate cya ein la alee oiafelera mes a\ aisle, ena: s' eve alee Aug. Buttes desMlorts oo sys sce eesle esis hei Sept Buttes des; Morte. ss yc. cae seek eae ee Aug. PVE GESWGOS VP NLOLES e/a eieloeierercleve wi s\biey wlsiaie lease 3 May Cedar, Washington county.............. Aug Cedar, Washington county.............. Mar Cedar, Washington county.............. Jan Cedar, Sheboygan county. .............. Oct Clover Leaf lakes: Goldemy oc ey Mcneela nae ae Aug. GoldenwRode ieee cles Uae elsisieneie la) ak Aug. Gren heraneke Oye sreree state eres tal oreren syeeovore: sel re Aug FAS Va noe ibelare ere Riera ered earn crenata Aug JEW OVS cuenta Misa Sten east pear Saen te Ret (Rt ets aa Pa Aug TE EYER WIN a A APIS Etee ei aA UBURE Tnuueae Ay Aug. Sa OC Kye aa bea anenlaatalaiatn aieieralnsetecsiccnlerete Aug SOTTO Keates aie con cron mar eeencly aaees Lay Aug Shamrock.. eke eis Aug. Eagle River lakes: EOE ep tet tase a oie h eins al eh ote a ol el ciiaray stoners! s)~ Aug Hagle Aug SAE earereey st ieke rata lol whats Soialete aieiataisviateves Aug CORIGT? aig id Binal y Sicsiekescie ama en gece aca Ea ps AAU Aug (CHPET OR Ce A Bim caer at a eRe ES Aug MD TIT Peep scan al Cae has sleimesalnmtater ate auet tints Aug ND TT espe tere sene tsar ei te sie sieh a sietanelene wi auenltece ats Aug BOWUI Keane pe tevencrorsiaie va miat aves lais onal alevmisteteiala lees Aug Rene area yeictcntter st svavicls oral sucsioloy ofaiele fove\alctinr alate Aug WSO a SIN Che ees ralaiecatelstcarelst eevee ieee Aug pGllawarls inches srercrercis sicrercial cess eravcisse ots Aug Wolony Isis? Gana adciohond ne me opeoigcor Aug RUE rte case cca val tect cliadesw laier'e eeiniainre, biedets Oct. WH POLES COUMEY Li's ccs is)cic siecle cies ss Aug Wine isamimess MICH saris) on sicisie wereisicie einiels Nov PSNR Mice Oa celaiis cistalel cla ovdld ce: stata on Slesie ote Sept MaSURESRPIMNRE eS eral a aU evs, 2/< cic) dears a aiese #! tre scebere. oy Aug PPRNSPELB MST Ra ST Eta ois cs sNistel'e ails. ales ocacals, s-o1 as Aug MAR Tie eee ted otc iairs sisi n1 Se ae cia levels) (ai see a//6 Aug PLO ioe sisys ic clase a Wleis a dew ais July EA PVT RSME operas is eiaiicreia a leialsielwe ult Souler aiavs Aug ACO VCTCLLTMMERIU AT aVCS Live tcl lalt ce sievericiaveig: malay alate Aug MarR WSR DIE ete atebete glarate cl eile acai! Occ acy'e es May SEM rales Uses sf wotels, cee ee ste wie 4.- Sept RRR Re divine lai Walstai id mie dialed! aise abel e Aug BURP ete aia che) fdiole sd shana)? G ccs 0 sia Sie Aug PURRM MEIC Rian cll ts fu Al atslas d aty'vsSeiae's sins 4 Aug PRMIERRIGH tea ree ahi hacia a Wiciottasy ta Wiel ip pyxiclm ssn aieie Aug Date. Vol. in cem. "6 PLANKTON OF WINNEBAGO AND GREEN LAKES. Tasie III.— Continued. Vol. in Name of Lake. Date. ete DMAWANOM ei iais wee auiccsis sisisel eure esse Aug. 9,1900...... 114.24 PSE ENDO) oA BA mein Retold Rie rINd Bne Gala He AUIS OL lOO La eer 107.10 Silver, Forest county................0.- Septs 22, 1899s aaee 63.78 COMEH NOM Sm ne en ase) 5 eae et ae Sept. 23, 1899...... 71.4 RS NHLOD OVS Sey ie cea A SN ue IA RUA NE Aug. 12,1900...... 171.36 PSY ROV AVS cre val Sea Avs A eer AA AG i Case SAY el an MT Aug. 11,1901...... 52.36 SJL ROPAYS) ips pels eae a tek CRI NUP E OetpO HUAI Aug. 12,1902...... 54.55 SS NOU AY SOUT EES ea ATE aI Tene nee te ae In Lue ee Sept. 25,1899...... 107.10 Waupaca lakes: Rainbowee ce secu race tain as July 29,1899...... 111.15 IMG @rosseny Rei tena Wii san Bee ws July 29,1899...... 73.30 TES ORE OTS bier esl Aine ieh er bt A Nea AIA AUNTS SY RICA July 29,1899...... 107.10 Columbians ge aoe sceie sei lye sO SOO leer 104. Beasley, sisiseccc: cues ives ows coat one July 30,1899...... 95.2 IWANNE COMME Ai wlan luen alae avereiens ete els July 24,1899...... 110.91 WANMECONNO: J.) 6 niece aoe See ene Aug. 6,1899...... 94.6 IWAnnecOnIe see ae eee eer ane ene eee Aug. 24,1899. ..... 64.26 IMME CONTE laa tis ie ele enna Sania May 30,1900...... 17.6 APPENDIX. 77 TasLeEIV.—Numbers of Diaptomus minutus and Diaptomus sicilis per square meter in Green lake. Date. No. Date. wed No. Date. No. 1899. 1900. 1801. July 16....} 163,744 || July 2.. 159,936 || Mar. 9....| 66,640 Aug. 1....| 706,384 || July 16.. 198,016 || Apr. L....| 121,856 Aug. 25....; 134,470 |; Aug. 4.. 634,032 ;| Apr. 20.... 32, 368 Bepietsess. 1) 205156) Aue, 18) 289, 408 || May 4....| 57,120 Oct. 4....| 280,840 || Sept. 3.. 447,440 || May 18....| 34,272 Wet og: o 241,808 Sept. 15.. 127,568 || June 1....; 47,600 Octal. 25,704 || Sept. 29.. 198,016 || June 22....| 177,072 Nove 2t 28. 32,368 || Oct 16.. 171,360 || July 8....| 215,152 1900. Oct) 272: 102, 816 || July 20....| 293,216 ehertiyg loess). 28,560 || Nov. 10.. 43, 792 }| Aug. 3....|. 205,632 wan): 206. 10,472 || Nov. 24.. 38,556 || Aug. 27....| 60,928 Feb. 23.... 78,064 || Dec. 21.. 87,584 || Sept. 18....| 116,144 Mar. 22....| 228,480 1901. Ocha 19 Ee 95,9 200 Ayr: 2053: . 34,972 | Jan. 14.. 719, 968 |) Nov.) 9. 2.: 53, 312 Wien Won. el 146,608 4) dani: 25%. HoV2IG: Wi Dee Gee.) hv d2ioos yaks: 91, 392 He X:) oS ae 106, 624 1902. dune 2.... 47,600 || Feb. 23.. 137,088 || Feb. 19....} 110,432 June 16....| 158,032 78 PLANKTON OF WINNEBAGO AND GREEN LAKES. TasLte V.—Numbers of Diaptomus sregonensis per square meterin Lake Winnebago. Date. No. Date. No. Date. No. 1899. 1900. 1901. July 5-11..| 12,13 Mar. 3.... Brey Welaya, Ba 4 357 July 12-18..| 12,852 Mercier 476 Beb:, -32.... 595 July 19-25..| 44,030 |; Mar. 27.... 952 BepawiG ae 307 Ju.26-Aug.1| 54,978 AMOI, sine os 7,616 Mar. 2... 238 AUER Peeing ayer) aioe a Shae ae 952 Wikwey TS 65. 714. Aug. 9-15..} 21,420 May 24....| 16,184 April tae. 5, 712 Aug.16-22..| 21,896 June Q....| 16,184 AMO Piao 9,044 Aug.23-29..| 16,184 June 25....| 19,992 Miciy eteleaee 2,380 Aug. 30- Jaly 297 ea ter oes. June 8....| 48,552 Sept.5....| 19,992 |) July 238....) 20,944 June) 2524. 952 Sepie Loree ois2s Aug. 22....| 34,272 July 12....| 21,896 Octaoteet: 8, 092 Sept, (Si..e| LO) ole July 27....! 11,186 Ocire Zien i oS Sept. 22....| 15,232 Aug. 24....{ 94,486 Nov. 4....! 39,984 Ota 26: 5, 712 Sept. 13....} 119,000 Nov. 25.... 9, 758 Oct 20555.) lane Sept. 28.... 7,616 1900. IMON/s Ose 5 ipo ally Vey Oct.) 12.7 aos ais alicia: 714 Nove, 2h 7,616 Nov. 2....| 44,006 eng OTe ee 952 IDEGS: Davos 2, 856 Nov. 16....| 32,368 eb AG x57 238 —— Taste VI. Numbers of Epischura lacustris per square meter in Lake Winnebago. Date. No. Date. No. Date. No. 1899 1899 1900 July 5-11. 714 Aug. 16-22. 476 June 9Q.... 6,188 July 12-18.| 13,566 Aug. 23-29. 1, 428 June 25.... 238 July 19-25. 2,656 Aug. 30- AJiulky Oosse 5, 950 July 26- Sept. 5 952 July 28.... 476 Aug) 1) 31178) il Sept. 16.5 5. 476 || Aug. 22.... 238 Aug. 2-8. ae) 1900 Sept. 22.... 238 Aug. 9-15. 1, 666 May 24.... 714 APPENDIX. 79 TaBLeE VII.— Numbers of Epischura lacustris per square meter in Green lake. } Date. No. Date. No. Date. No. 1899 1900 1900 ry Gs) 3... 3, 808 Jah; Bocas 2, 856 Nove L0n ss: 3, 808 ANyoVey, Nea ly albthe kets) July 6... 1,904 1901 Aug. 25.... 1,904 Aug. 4....! 22,848 June 22.... 1, 904 Sept. 18.... 238 Peg 1B a: 3, 808 Oiullyam Sere: 3, 808 Wot aes) (138328 Sept. 3....| 18,328 ANGE Baca 952 Wek) 19.03: 3, 332 Septal one: 1,904 ANG PAs alos 1,428 Wet sl...) 3, 808 Sept. 29.... 476 Octo te: 8, 468 Noy. 27 238 Oct. 27 2,142 Taste VIII.— Numbers of Limnocalanus macrurus per square meter in Green lake. Date. No. Date. No. Date. No. 1899 1900 1901 July 16 3, 808 UL eee cle GOL Apres 2032 4,760 Aug. 1 24, 752 July 16....) 47,600 May 4.. 9, 520 Aug. 25 O52) Ante sl OUa IO) May. 18.) 3, 808 Oct. 4 7,616 Aug. 18.... 5, 712 June 1.. 7,616 Oct. 19 3, 094 Sept) ace |) li, 136 June 22.. 22,848 Oct. 31 238 Pept lo 28: 952 uly Sie 714 Nov. 27 7,616 Sept. 29.... 1,904 July 20.. 952 1900 Oct: 16.33: 1,904 Ao Sine 952 Jan. 13 238 Och Ais: 476 Aug. 27.. 5, 712 Feb. 23 952 Nov. 24....| 19,040 Sept. 18.. 3, 808 Mar. 22 7,616 1901 Oct. 19s 1, 904 Apr. 20 36, 176 Jane aa 476 Novi 95 1,904 May 5 8,468 Diane ena ca ea emiby.s (Le Dec: 92% 238 May 21 15, 232 Heb. 23....| 13,328 1902 June 2.... 1,428 Mar. 9....| 6,664 Feb. 19 7,616 June 16.... 9,520 SDT ee alanis eho ED 80 PLANKTON OF WINNEBAGO AND GREEN LAKES. Taste 1X.—Numbers of Cyclops brevispinesus per square meter in Lake Winnebago. Date. No. Date. No. Date. No. 1899 1899 | 1900 July 5-11. 8,806 || Sept. ie. | 7,140 || Sept. 22.... 1, 904 July 12-18. OOO Oct anise. 2 380 NOV Ores 1,904 July 19-25. by 2500 || Oct, 2s 476 1901 July 26- Nov. 4... 952 || Mar. 30.... 238 Aug. 1 13, 328 1900 ile WARY 10, 472 Aug. 28.| 17,612 ||May 11....; 5,712 ||July 27....| 19,992 Aug. 9-15. HE236)/ (aly, v9: 125376) Ane: 245 15, 232 Aug. 16-22. 5,750 || July 28....| 20,944 ||Sept.18....] 30,464 Aug. 23-29. 6,664 || Aug. 22... 1,904 |/Sept. 28....| 19,992 Aug. 30- Sepia sea 2,856 || Oct.. 12.... 3, 808 Sept. 5 5, 236 TasBLE X.—Numbers of Cyclops pulchellus per square meter in Lake May 11..... 18,088 Winnebago. Date. No. Date. No. Date. No. 1899 1900 1901 INOW Biotec 5, 712 May 24.... 8, 568 Mar. 30.... 238 Nov: (25.25% 6, 664 June aon 1, 904 DNjorelll Pylonoe 3, 808 1990 Octe720-0 5, 712 | June §8.. 7,616 Aaa Olea 7,616 INOW) Gagso 952. June 25.... 3, 808 Marhiyanere 238 || Nov. 21.... 1,428 Sept. 28.... 3, 880 Mar. 0175.2 7,616 1901 Oct: 12: 952 April 28.... 3, 808 Jan. ae 238 INOVa ie 2seie sll pelos oe APPENDIX. 81 Tasie XI. —Numbers of Cyclops Leuckarti per square meter in Lake Winnebago. Date. No. Date. No. Date. No. 1899 1898 1900 July 5-11.. 4,998 Sept. 16 17, 136 July 28....| 18,088 July 12-18..| 16,136 |! Oct. 7 3,094 || Aug. "22....| 10,472 July 19-25..} 13,804 Oct. 21 476 Sept. 8....| 9,996 July 26- Noy. 4...... 238 SEOs PSs a6 7,616 Aug. 1, 16,660 1900 Ochi. 1, 904 Aug. 1-8 .| 17,136 || Mar. 17 952 || Oct. 20....| 2,856 ‘Aug. 9-15 Ts Gale. Mey, lal ti 25, 704 1901. Aug. 16-22 11, 424 May 24..... 2, 856 Dilliya wl eee 952 Aug. 23-29 11, 424 June 9 1,904 Aug. 24....| 12,614 Aug. 30- June 25 952 Sept. 13....| 19,040 Sept.5| 21,420 || July 9 32, 368 | Sept. 98....| 1,904 Taste XII.— Numbers of Cyclops prasinus per square meter in Green lake. No. 28, 560 104,720 23, 672 5D, 216 112, 336 62, 832 41, 888 19,040 1, 428 15, 232 22,848 19,040 15, 232 17,136 11, 424 1,904 Date. No. 1900 July 16....| 22,848 Ao on aol) INA, Biss) Aug. 18....| 60,928 Sept. 3....| 59,024 Sept ose 3845202 Sept. 29....) 38,080 Oct eAGre sain Ope 22, Oct. 27....| 85,680 Nova LOR ee iiesaon Noy. 24....; 26,656 Decws2li 9,520 1901 PAW MeO ae anos Feb. 9 13,328 Feb. 23 15, 232 Mar. 9 9, 520 No. 13, 328 5, 712 3, 808 3, 808 7,618 y, 520 1,904 19, 040 15, 232 39, 984 74, 256 30, 464 20,944 32, 368 17, 136 89 PLANKTON OF WINNEBAGO AND GREEN LAKES. Taare XII]._—Numbers of copepod larvae per square meter in Lake Winnebago. Date. | No. Date. No. Date. Neo. 1899) 1900 1901 July 5-11.} 11,186 Wiewes glee 40, 222 Vein, 9.4 1,904 July 12-18 74,970 Wiles “OAT 4 45, 696 Hebwaee 952, July 19-25.) 69,496 Apr. 28....| 367,472 Feb. 16.. 1, 904 July 26- May 11....| 297,976 Migie, B.- 952 Aug. 1} 8,568 May 24 115, 906 Mar. 16.. 1,190 Aug. 9-15 50, 932 June 9 12,376 Avorelane 17,136 Aug. 16-22.; 48,078 June 25 49, 980 Apr. 2i.. 57, 120 Aug. 23-29.| 34,510 July 9 31,416 May 11.. 30, 464 Aug. 30- July 28 129,472 | June 8....| 118,048 Sept. 5) 51,408 Aug. 22.. 101, 150 Vine 2Zeooo. Wo, 28% Sept. 16.... 6, 664 Sept. 8.. 42,840 dwilhy 127 Dele Ocheenwrs: 49, 504 Sept. 22.. 25, 704 Yuli Os. 3, 808 WOWs be. 32, 368 Oct. 20.. 2, 856 Aug. 24.. 27, 608 Nov. 25 48, 552 Nov. 6.. 8, 568 Sept. 18.. 48, 744 1900 Nov. 21 1, 428 Sept. 23.. 39,508 dew,’ al 12,376 Dec. 5 1,904 Octal k 21,896 Jan. 27 13, 804 1901 Nove 2 22,848 Feb. 17 18,088 || Jan. 5 952 | Nov. 16.. 20, 944 Mar. 3 21,896 | Taste XIV.— Numbers of copepod larvae per square meter in Green lake. Date. No. Date. No. Date. No. 1899 1900 1901 July 16.... Vulky Be soc 1,904 April 1....! 11,424 Aug. 1....| 249,424 July 16....} 100,912 April 20.... 5, 712 Aug. 25....| 69,258 Aug. 4....| 172,264 May 4....| 18,328 Sept. 18....| 73,304 Aug. 18....} 310,352 May 18....| 62,832 Oct 43) |) 287560 Sept. 3....| 137,088 June 1....| 319,872 Oct 19 9,520 Sept. 15....| 67,544 June 22....| 32,368 Oyo Bosco Bes Ue Sept. 29....| 57,120 July 8....! 84,152 Nov. 27 ...| 72,352 OctyGra 1,904 July 20....| 118,048 1900 Oe Bl ssooh Bou Aug. -3....| 144, 704 Aer We 555 p47, ow Nov. 10....} 386,176 Aug. 27....| 180,880 Jan. 20....| 28,560 Nov. 24....| 51,408 Sept. 18....| 317, 968 Feb. 23....| 20,944 Dec. 21....| 196,112 Oct. 19....| 28,560 Mar. 22-222!) 195,040 1901 Nov. 9....!' 22,848 April 20....| 22,848 Jan, 14....| 45,696 Dec. 9....{ 74,256 WEY Byega- 1, 904 Jan. 25....| 382,368 1902 May 21....| 59,024 Feb. 9....| 95,200 Feb. 19....| 38,080 June 2eeee|) ol 8i2 Feb, 23....| 61,408 June 16....| 142,800 Mar. 9....| 20,944 a SS APPENDIX. QR TasLE XV.— Numbers of Diaphanosoma brachyurum per square meter in Lake Winnebago. Date. No. | Date. No. Date. No. 1899 1899 1900 July 5-11..! 14,280 Sept. 16.... 1, 428 Octhgy Gree 7,616 July 12-18..| 28,322 1900 1901 July 19-25.. | 194, 208 Wiley SAL ae 238 May; ellie 476 July 26- May 24.... 4,760 aly pee 9,520 Aue th 1165620 June Q.... 238 VO Piacoa) Waar Aug. 2-8.]| 32,3868 June 25.... 952 Aug. 24....| 22,848 Aug. {9-15./ 30,464 ube Qeere 1, 428 Septmlance. 952 Aug. 16-22.|; 19,992 July, 28.2.5) 12; 852 Sept. 28.... 2,142 Aug. 23-29. Be 1} Aug 226s | ao ,084 Octane 714 Aug. 80- Sept. 8....) 17,850 INOWe Boose 3, 808 Sept. 5| 11,424 Sept. 222... 4,284 TaBLe XVI.— Numbers of Daphnia hyalina per square meter in Lake Winnebago. Date. No. Date. No. Date. No. 1899 1900 1900 July 5-11./ 16,660 ay oul se 238 Novy.) 20522). 4,284 July 12-18 30, 464 Veals) Allo ae 2,142 Dec. on ae. 476 July 19-25.| 38,060 INR, OAS one 952 1901 July 26- May 11....} 18,088 Miayap alien 476 Aug. 1} 105,196 May 24..../ 100,198 June 8....| 22,848 Aug. 2- 8.| 12,376 June 9....|. 13,328 une oes 5, (12 Aug, 9-15.} 42,840 June 25....| 14,280 Mwy Weeden Lely UBS Aug. 16-22.| 44,268 Vivi ss ke 952 rae ie AT ie 8,568 Aug. 23-29.) 40,936 July 28.... 6, 664 Aug. 24....| 10,472 Aug. 30- Auge 224.1 405192) (| Sept. L253. 2,856 Sept. 5| 40, 936 Sept. 8....| 51,646 SepiEy2seeee 4,998 Sept. 16....; 14,756 Sept. 22 ...| 16,184 OGty ADs." 1, 904 Oete iii a: 476 Oetary, Gin) Sy SUS NOvels Qie el damenls 9 eee 4 Tee 5, 712 OCt 20) as: 5, 236 INovVAWIGaaee 4,284 ING As. 3 7,140 Nova, 6.2. .|) 36, 176 Nov. 25.. 4, 284. 84 TasLe XVII.— Numbers of Daphnia hyalina per square meter in PLANKTON Of WINNEBAGO AND GREEN LAKES. Green lake. 13, 328 93, 396 4,760 3,094 22,848 26, 894 TasLe XVIIL.—Nuimbers of Bosmina per square meter in Green lake. Date No. Date No. Date | No. 1899 1900 1901 July 16.. 53, 312 June 2 9, 520 Jan. 25....|° 19,040 PATTI Er psec! 3, 808 June 16 7,616 Heb 9.08 7,616 Aug. 25.. 2,380 July 2 635, 936 Melb, (285 4ea hu ceeee Sept. 18.. 23, 800 July 16 325, 584 IWigm, Qooos 3, 808 Oct 4% 24, 752 Aug. 4 12,376 AN joe bs oh 3, 808 Oct. 19.. 94, 752 Aug. 18 Dele May a4 eau 1,904 Octal 38,080 Sept. 3 UA See i diwwave, DAs 5 By, (te INOVe eee 173, 264 Sept. 15 13, 328 | dwlky Sogac 7,616 1900 Sept. 29 By, TY duilhy 2Osco- 3,808 Janel aeee |) 14240 Oct. 16 1,904 INTER. Basan 9, 520 Jane 2One 79, 968 Oct. 27 By 7) Sept. 18.... 7,616 Heb. 23....|| 74,256 Noy. 10 59, 024 Octs 19) 3,808 — Mar. 22.. 138, 992 Nov. 24 20, 944 Nov. 9....| 118,048 Apr. 20.. 36,176 Dec. 21 19,040 Dec. 9Q....| 165,648 May O5.. 9,520 1901 1902 May 21.. 4,760 Jan, 14 3, 808 Feb, 19....| 380,940 eget (ae APPENDIX. 85 Tasie XIX.—iWNumbers of Hurycercus lameliatus per square meter in Lake Winnebago. Date. 1899 July 5-11.. July 12-18.. July 19-25.. July 26- Aug. 1 Aug. 2 8. Aug. 9-15. | 1,28 No. 23, 086 66, 402 22, 134 8,568 952 Aug. nic 3,332 Date. 1899 Aug. 23-29. Aug. 30- Sept. 5 Sep ie Grea: Ocha Zio INOVeN ace 1900 JNO. A. 6 5 No. Date. 1900 | June Q.. June 25.... ule Oasce uly 28a FeNVOUSe 3 PAG Oe Septic case: 1901 diwnae) Boo ewe TaBLe XX.—Numbers of Chydorus per square meter in Lake Winne- bago. Date No. Date No. | Date No. 1899 1900. | 1900 July 5-11.} 19,516 Jame 238 Dec. 5. 1, 904 July 12-18 9,520 Mardi Qin 476 1901 July 19-25 2, 856 AN ore, PAShG 2, 856 Jane) D2 238 . July 26- May 24.. 1,904 Apr. 27... 952 Aug. 1|{ 16,184 June Q.. 3, 208 WEN? alike 1,904 Aug. 2-8..| 11,900 Shale On: 952 June 8.. 2,142 Aug. 9-15.| 28,560 July 28.. 118, 048 July 12 4,760 Aug. 16-22. 1, 904 Aug. 22.. 6, 664 July 27 21,896 Aug. 23-29. | 238 || Sept. 8.. 14,280 || Aug. 24.. 1, 904 Sept. 16... 952 Sept. 22.. 18, 088 Sept. 28.. 476 Oetcrak ss. 476 Octo: 7,616 Oct 2" 952 Nov. 4.. 2,618 Oct 20%;, 34, 272 Nowars 2) 3, 808 Nov: 25.... 4,522 INGvenn. On: 133,518 Nov. 16.. 2, 856 1900 Nov. 21.. 10, 472 952 TInt ene a Gas 86 PLANKTON OF WINNEBAGO AND GREEN LAKES. Taste XXI.—Numbers of Leptodora per square meier in Lake Winnebago. Date. No. Date. No. Date. No. 1899 1899 1900 July 5-11. 714 Aug. 30- Sept. 8.... 357 July 12-18. 052 Sept. 5 714 Sept. 22.... 238 July 19-25. 1, 904 Sept. 16.... 1,904 Oct 20225. 238 July 26- 1900. 1901 Aug. 1 1,666 May 24.... 238 May 11.... 714 Aug. 2-8. 952 uneh WOeeee 238 June Sees 476 Aug. 9-15. 238 June 25.... 714 July 120... 1, 428 Aug. 16-22. 238 July 28.... 238 UGE aoa ee 238 Aug. 22-29. 476 AN ees PA a5 476 TaBLeE XXII.— Numbers of Cypris per square meter in Lake Win- nebago. Date. No. Date. No. Date. No. 1899 1899 1900 July 5-11.) 1,428 |! Aug. 23-29.| 11,186 || June 25.... 476 July 12-18.| 10,510 || Aug. 30- July (oe) plowed July 19-25.| 53,788 Sept. 5} 9,520 || Aug. 22....| 1,904 July 26- | Sept. 16....| 17,612 1901 Aug. 1 714 1900 Tunes Gee. 714 Mae OBA ao Tl Maye: dyes 952 || June 25..../ 9,520 Aug. 9-15.| 15,232 || May 24....) 7,616 || July 12 ... 952 Aug. 16-22.| 16,422 || June oe 2, 856 APPENDIX. 87 TaBLE XXIIL.— Maximum depths of Wisconsin lakes. Notrr—It has been found, by experience, that the popular ideas in regard to the depths of lakes are utterly unreliable. Consequently, although only a small number of the Wisconsin lakes have been accurately sounded, it seems best to append a table of those depths that are known, to serve as a matter of reference. In 1897 a reconnaissance of a considerable number of the Wisconsin lakes was made by the author as preliminary to the study of the lakes undertaken by the Natural His- tory Survey of Wisconsin. Although this was a hasty trip, considerable care was taken to determine the greatest depths of the lakes visited, and where subsequent detailed sur- veys were made, it appeared that the record of the preliminary trip was quite accurate. Under the auspices of the Survey detailed hydrographic surveys were afterwards made of the following lakes: Lake Geneva, the Oconomowoc lakes, Lake Beulah, Elkhart lake, the Waupaca lakes, Delavan lake, the Lauderdale lakes, Green lake, Lake Mendota, and Lake Monona. The figures given for these lakes, then, are authoritative. The figures given for the other lakes are the result of only a cursory examination, with the probability that the deepest parts of the lakes were examined, but with the possi- bility of some error. The depths are the result of a personal examination by the autho r and were not obtained by any hearsay evidence. Name. Township. Range. County. Depth. Feet. Bassilakes.i. bic secu Bea INE Ceee XM ne wen) aamolade, mova: 19.5 SOA VET eee ai anecu seh SeNe ae XVIII E....| Waukesha ....| 47.6 Beulah eye ca eabes AGING ey DOWANIE Tiss cal) MEN Werte | nelle doa esac TUONO SA SEN SM A ATO RG Sear ae LE cet RO 95.5 RIVET pare eset amine NUL De SAG SUN RU Cas orld MI opL MG SHC el lia an ae 51.5 JRROMENGNS Loh i ake Ate) RU aie Nes aR aN A aa Dee aa 40 UI DURST ie oh oets HES eas Dy eee ae Pear oe chs [ESiedive Neale acre oala 67 [Bone Gli 48 BAU es as RO INGa so DOVE VD) BINA Horesti sce 61.7 OO tee Seen ts AGING nn DWAIN EID ie Walworth...... 25.4 Buttes des Morts....| 18&19 N| XV & XVI E} Winnebago.... On (CHE EA see GHNG XXXIE....| Sheboygan....| 39. Cedars. 222... A aatnaeas aby XOX aoe Washington....| 104.7 Clover Weats i). AG IN oo ose EXOV Ie Ween Sitawaln oneness |peyee ies Golclene RO: oe eee ee Wen NUL AUA RN Mee NAT AB SEAT RUN CoH Si EOD ae UR 387.4 GPE ISIS Gs A IU Hie Piet esc De ra eg Ea es CM a 48.7 Suz TEES OOH ER eso S'S Gt A a a ONG SLEIGH UA MCT A ae ee A 39.7 Crooked ye nseie eee TRAN SAE XVII H..... Waukesha ....| 16. Delays ee oe QING es SVL So oe Walworth...... 36.7 IDF neve’... os. c.. 15) Nols a 5 KOVR ee Fond du Lac..| 52. Hagle River lakes ....| 389 &40N| X & XI E..., Vilas & Oneida.|........ CSTTISTI Sola ise. Se [eee eal Me ROA A EISBN Vea Ciara mE UR 16.6 IO AIVEN Ee Se Sik Beales CAT I Ea TLIO A OO a ag ST 16.2 SELES yo Cig Se eve IER HO EEE NE rae oe Ue AO A 49.7 QITTIGIP g 5 bo ES ASAE Ae EI rai Ep UAE Eos AWN ia en i eR LN 29.2 RD py TBAT edin BST Te Aa TS ea eC Ee nO 15.5 MAAS UR ELOY: (ace kil bic.c's's oe BIN 33%, XVIII E....| Walworth ..... 16.5 sar bare cresyl tai GENES, DOLE DEMO A Sheboygan ....| 113.2 OWI)! 626s eis ARSE (ito ely aaa VALE Dia Waukesha ....| 50. Garvan ge ens SNe eink XVIII E....| Waukesha ... 36.1 Genesee, North ..... STAIN eta DOV ACH Waukesha ....| 36.4 Genesee, South ...... TiN sae, VAD soir Waukesha ....| 47.6 88 PLANKTON OF WINNEBAGO AND GREEN LAKHS. Taste XXII.—Maazimum depths of Wisconsin lakes—Continued. Name. Green IRONY Gs anc onan oour Lac LaBelle Lauderdale Green eoee coos eee e ee ee eeccec cores eeececoccace eee e ee ee pe oe ee ese or cone cee sec ee oe vee s oe ecoet cone eeeec rece ce ee oo ee se2ce - cee ec ee ee te eee Long Medicine Mendota Monona IMOu Seka Meee Nagawicka Nashotah, Upper .... Nashotah, Lower .... Nemahbin, Upper.... Nemahbiu, Lower.... North Oconomowoc Okauchee eecee eee eto eee eceecereces Co ece eoee cece ee ee ee cece ceo e toe eee. ee ee eoeeecoee coo eecce ease ee ee co oe oe ce oece coer ec oert ee «200 eceece ceo TET AW sys? a eee ean a nea Powers oeecece veer ees s ce oee Summit TWA Ais aeteee ein posi Lake Mary......... Vieux Desert Waubesa CC i ese ee Veoveeevece Township. Range. XVI, XV1 EH [Ni XI0& XILE eos oee toeces ece ces eeee ce re ae ecec er eee eace eo oe oe eeceee ee oe + se eee = 2eee eecece ee cee e eee. eye ee sec ee coooe eecceoe cont ee ee ee econ eee ees ze eee eeceee ee ee ee cose te oe esac owe co ee se ee wees ee ee es oe oe e ener eect ce eevee ee ee ce cee ecco see ee & XVE... NOCH? 1D) oo XVI, XVILE XIV E ee ee os eee rm ee ew ee woe ne eeee see ee eeoe eet ec coos County. Walworth Green Lake.... Dane Waukesha .... Walworth. .... seen reece pe ee eo ee ‘Green Lake ... Fond du Lac.. »o ee ce ee sees eee er ce cece e Waukesha .... Waukesha .... Waukesha .... Waukesha ... Waukesha .... Waukesha .... Waukesha... Waukesha .... Waukesha . Oneidarey sees Waukesha .... Waukesha ... Walworth and Kenosha.... Winnebago & Waushara... Forest Onesie ene Waukesha .... Green Lake... Forest Langlade...... Oneida & Vilas Kenosha peocc ees ec oe eo eoeeleo rs ee ee ee ee eo Depth. eeee ceee APPENDIX. 89 Taste XXII.—Marimum depths of Wisconsin lakes.—Continued. Name. Waupaca: Columbian Dake Long @eove cece ee ee >>, ece2eo esos see eo ee eo ee wo oe eececeeeosee @seec ease reese oe eece tees po ce oe eseeec trees cece se Teale eae ese n ec eee ew wees ee ee ee ee wo Township. eee eo nme oe ee e202 ee eee ee ee ee cere ee ee ee eee eee cose ee ea ee sees ee ee ee eeee ee ee oe see e cece ee eee 2 se oe oe e eee ce ee ee e206 wee eo oe 15& 20 N 19 & 20 N Range. eo ee ee oe ee wo oe ose ee es ae oe ae sees ee ae ee woe ee ee ee re ee wooo e pecs sec ese ee eae ewes ee ee ee ee sees ee ee ee eo oe eee es ee ee ee eee oe ee ee ee we oo oe eoeoa eee see we oe eece ee ee ee ww oe ee ee ee ee ee oe esl eons eeee eee Connty. ee ee ce eee Be ee oe oe ee eo se ee De oe woe core coe ve eee se ee oe cee ee eee eo ee eo ee eee e eres ce ee eee ee ee ee ee we ee ew oe «e222 ees se ee oe Oe ee ee ee ee oe ee oe e008 ae ee ee ee Be oe cee e ee ee eo ee ooo ee ee wee oe MM Be oe Oe Yoorses cece Winnebago and Fond du Lac Winnebago.... | Depth. taf INDEX. Abyssal fauna, 5. Anabaena, annual distribution of, 15. Annual distribution of the organisms of the plankton, 11. Anuraea aculeata,annual distribution of, 19. cochlearis, of, 19, quadridentata, annual distribu- tion of, 20. Aphanizomenon, annual distribution of, 16. Apstein, 13, 18, 19, 21, 22, 24, 25, 32. Asplanchna, annual distribution of, 21. Asterionella, annual distribution of, 11,14. annual distribution Balance of life more easily maintained in deep lakes, 66. Birge, 9, 24, 25, 26, 32, 33, 57. Bloom, discussion of, 36. Bosmina, annual distribution of, 33. table of numbers per Square me- ter in Green lake, 84. Burckhardt, 32, 36. Buttes des Morts, 2. Centrifuge, use of, 9. Ceratium hirundinella, annual distribu- tion of, 18. Characteristic species of deep and shallow lakes, 62. Chydorus, table of numbers per square meter in Lake Winnebago, 85. sphaericus annual distribution of, 35. Classes of lakes, comparison of faunae and fiorae, 62. Classification of lakes, 6. Clathrocystis, annual distribution of, 15. Closterium, annual distribution of, 14. Codonella, annual distribution of, 19. Collections, on Green lake, times of, 5, 7. on Lake Winnebago, loca- tions of, 4. method of making, 8. Conochilus volvox, annual distribution of, 22. Copepod larvae, annual distribution of, 29. Counting plankton, method used, 10. Crustacea, important in total plankton in < deep lakes, 49, 50. Cyelops brevispinosus, annual distribution of, 26. table of numbers per square meter in Lake Winne- bago, 80. enayel . | OF lus, local distri- bution in Wiscon- sin lakes, 27. Leuckarti,'‘annual distribution of, 28, pulehel- table of numbers per square meterin Lake Winnebago, 81. prasinus, annual distribution of, 29, table of nnmbers per square meter in Green lake, 81. pulechellus, annual distribution of, 27. table of numbers per square meter in Lake Winnebago, 80. and C. brevispinosus, local distribution in Wisconsin, 27. Cyclotella, annual distribution of, 11, 14. Cypris, 36. table of numbers per square meter in Lake Winnebago, 86. Depth, a factor in horizontal distribution, 56. Depths of Wisconsin lakes, 87. Diaphanosoma brachyurum, annual dis- tribution of, 30. table of numbers per square meter in Lake Winnebago, 83. i) al 9 Dinobryon, annual distribution of, 17. Daphnia hyalina, annual distribution of, él. table of numbers per square meter in Green lake, 84. table of numbers per square meter in Lake Winnebago, 83. pulexz var. pulicaria, annual dis- tribution of, 32. retrocurva, annual distribution of, 31. Deep lakes, definition of, 6. Diaptonus, rare in Pelican lake, 60. gracilis, annual distribution compared with D. oregon- ensis, 24, graciloides, annual distribu- tation compared with D. oregonensis, 24, minutus, annual distribution of, 22. minutus and D. sicilis, table of numbers per square meter in Green lake, 77. oregonensis, annual distribu- tion of, 23. table of numbers per square meter in Lake Winnebago, 78. Reighardi, distribution of, 62. sicilis, annual distribution of, 22, siciloides, in Cedar Lake, 60- 62. Diatoms, comparison of annual distribu- tion in Greenlake and Lake Winnebago with results of other authors, 13. Distribution, annual of the organisms of of the plankton, 11. annual of species, 60. Elkhart lake, 6, 27. Epischura lacustris, annual distribution of, 25. table of numbers per square meter in Green lake, 79. table of numbers per square meter in Lake Winnebago, 78. Epistylis galea, annual distribution of, 19. EHudorina, annual distribution of, 15. INDEX. Eurycereus lamellatus, annual distribu- tion of, 34. table of numbers per square meter in Lake Winne™ bago, 85. | Fauna of different classes of lakes, 62. Fish, relative value of deep and shallow lakes for the production of, 67. Flora of different classes of lakes, 62. Fragilaria, annual distribution of, 12, 14. Geographical distribution of species, 60. [ Gloiotrichia, annual distribution of, 16. ‘Green lake, 6, 7. comparison with Lake Win- nebago, 5. description of, 5. plankton compared with that of Lake Winnebago, 4. Heterocope, annual distribution of, 25. Horizontal distribution, 51. conclusions in re- gard, to, 58. depth a factor in, 56. table of collec- tions, 53. Isolation important in producing differ- ences in lake faunae, 61. Kofoid, 9. Laboratory on Lake Winnebago, 3. Lakes, classification of, 6. Lake Geneva, 6, 27. Lake Winnebago, 8. character of work on, 4. comparison with Green lake, 5. description of, 2. plankton compared with that of Green lake, 42. why chosen, 1. Lakes visited other than Green lake and Lake Winnebago, 7. Lakes of Wisconsin, maximum depths, 87. Large deep lakes, 6, Large deep lakes more productive than small deep lakes, 68. Larvae, copepod, annual distribution of, 29, INDEX. 93 Larvae copepod, table of numbers per| Plankton, constituents, relative import- square meter in Green lake, 52. table of numbers per square meter in Lake Winnebago, 82. Leptodora, table of numbers per square meterin Lake Winnebago, 86. Leptodora hyalina, annual distribution of, 36. Limnocalanus macrurus, annual distribu- tion of, 26. table of num- bers per sq. Marsh, 6, 10, 14, 22, 26, 31, 33, 51, 57, 62, 68, 69. Maxima of plankton, constituents produc- ing, 39. Measurement of plankton, method used, "9. Melosira, annual distribution of, 12, 14. Mendota, annual distribution of C. brevi- spinosus in, 26. annual distribution of D. ore- gonesis in, 24. Merismopedia, annual distribution of, 15. Methods of making collections, 8. Wassula, occurrence in Lake Winnebago, 13. ance of, 49. curves, comparison with curves of constituents, 51. curves, comparison with temper- ature curves, 49. maxima; produced largely by piants, 49. method of examining, 10, method of measuring, 9. of Green lake, compared with that of Lake Winnebago, 42. of othar Wiscousin lakes com: pared with Green lake, and Lake Winnebago, 43, tabie of total volumes per sq. meter in Green lake, 78. table of total volumes per sq, meter in Lake Winnebago, 74. total annual distribution of, 38, total volumes per sq. meter in various Wisconsin lakes, 75. Pleurosigma, annual distribution of, 18. Polyarthra platypera, annual distribu- tion of, 20. Poygan lake, 2. Reighard, 9, 52. Seligo, 19, 21, 22, 24, 32, 36. Shallow lakes, definition of, 6, Small deen lakes, 6. Species, distribution of, 60. Sphaerelia, annual distribution of, 17. Staurastrum, anvuual distribution of, 15. Stephanodiscus, annual distribution of, 13, 14. Steuer, 24, 32, 36, 39, 52. Stone lake, 2 Stony Beach laboratory, 3. Surirella, annual distribution of, 13. Syunchaeta pectinaia, annual distribution of, 21. Synedra acws var. delicatissima, annual distribution of, 12, 14. pulchelia, annual distribution of, 12. Synura, annual distribution of, 18. Navicula, annual distribution of, 13. Net, collecting, form of, 9. Wotholca foliacea, annual distribution of, 21. longispina, annual distribution of, 20, meter in Green lake, 79. Lingbya, annual distribution of, 16. Object of study, 8. Oscillaria, annual distribution of, 16. ' Pediastrum, annual distribution of, 15, Pelican lake, Diaptomus rare in, 60. Plankton, amount in different years, 41. collections, value of, 47. Temperature curves, comparison with comparison of collections over plankton curves, 49. muddy and stony bottoms, 59.| Thermocline, classification of lakes de- comparison of successive years, pendent upon, 6. 65. relation of Daphnia puli- constituents producing maxi- caria to, 32. ma, 39. Total plankton, annual distribution of, 38. 94 INDEX. Triarthra longiseta, annual distribution | Waupaca‘lakes, 2,716, 27. of, 20. Whipple, 13. Winneconne lake, 2. Uroglaena, annual distribution of, 18. Yung, 52. Voigt, 14, 19, 22. Ward, 9. Water fowl as distributors of species, 61. Zacharias, 18, 32. PUBLICATIONS OF THE Wisconsin Geological and Natural History Survey. 1. BULLETINS. The publications of the Survey are issued as bulletins, which are num- bered consecutively. Hach bulletin is independently paged and indexed, no attempt being made to group them in volumes. The bulletins are issued in three series, A. Scientific Series.— The bulletins so designated consist of original contributions to the geology and natural history of the state, which are of scientific interest rather than of economic importance. Heonomic Series.— This series includes those bulletins whose in- terest is chiefly practical and economic. C. Hducational Series.—The bulletins of this series are primarily designed for use by teachers and in the schools. The following bulletins have been issued: Bulletin No. I. Heonomic Series No. 1. On the Forestry Conditions of Northern Wisconsin. Filibert Roth, Special Agent, United States Department of Agriculture. 1898. Pp. vi., 78; 1 map. Sent on receipt of 10c. Bulletin No. II. Scientific Series No. 1. On the Instincts and Habits of the Solitary Wasps. George W. Peck- ham and Elizabeth G. Peckham. 1898. Pp. iv., 241; 14 plates, of which 2 are colored; 2 figures in the text. Sold at the price of $1.50 in paper and $2.00 bound. EBulletin No. III. Scientific Series No. 2. A Contribution to the Geology of the Pre-Cambrian Igneous Rocks of the Fox River Valley, Wisconsin. Samuel Weidman, Ph. D., Assistant Geologist, Wisconsin Geological and Natural History Survey. 1898. Pp. iv., 63; 10 plates; 13 figures in the text. Out of priat. Bulletin No. IV. Economic Series No. 2. On the Building and Ornamental Stones of Wiszonsin. Ernest Robert- son Buckley, Ph. D., Assistant Geologist Wisconsin Geological and Natural History Survey. 1898 (issued in 1899). Pp. xxvi., 544; 69 plates, of which 7 are colored, and 1 map; 4 figures in the text. Sent on receipt of 30c. Bulletin No. V. Educational Series No. 1. The Geography of the Region About Devil’s Lake and the Dalles of the Wisconsin, with some notes on its surface geology. Rollin D. Salisbury, A. M., Professor of Geographic Geology, University of Chicago, and Wal- lace W. Atwood, B.8., Assistant in Geology, University of Chicago. 1900. Pp. x., 151; 38 plates; 47 figures in the text. Sent on receipt of 30c. Bulletin No. VI. Mconomic Series No. 38. Second Edition. Preliminary Report on the Copper-Bearing Rocks of Douglas county, and parts of Washbnrn and Bayfield Counties, Wisconsin. Ulysses Sher- man Grant, Ph. D., Professor of Geology, Northwestern University. 1901. Pp. vi., 83; 13 plates. Sent on receipt of 10c. Bulletin No. Vili. Economic Series No. 4. The Clays and Clay Industries of Wisconsin. Part I. Ernest Robert- son Buckley, Ph. D., Geologist, Wisconsin Geological and Natural History Survey. In charge of Economic Geology. 1801. Pp. xii., 304; 55 plates. Sent on receipt of 20c. Bulletin No. VIII. Hducational Series No. 2. The Lakes of Southeastern Wisconsin. N. M. Fenneman, Ph. D., Pro- fessor of General and Geographic Geology, University of Wisconsin. 1902. Pp. xv., 178; 36 plates, 38 figures in the text. Sent (bound) on receipt of 50 cents. Bulletin No. 1X. Hconomic Series No. 5. Preliminary Report on the Lead and Zine Deposits of Southwestern Wis- consin. Ulysses Sherman Grant, Ph D., Professor of Geology, North- western University. 1903. Pp. viii, 103; 2 maps, 2 plates, 8 figures in the text. Sent on receipt of 10 cents. Bulletin No. X. Heonomic Series No. 6. Highway Construction in Wisconsin. Ernest Robertson Buckley, Ph. D., State Geologist of Missouri, formerly Geologist, Wisconsin Geological and Natural History Survey. 1903. Pp. xvi, 239; 106 plates, including 26 maps of cities. Sent on receipt of 30 cents. Builetin No. XI. Hconomic Series No. 7. Preliminary Report on the Soils and Agricultural Conditions of North Central Wisconsin. Samuel Weidman, Ph. D., Geologist, Wisconsin Geological and Natural History Survey. 1903. Pp. vii, 67; plates 10, including soil map. Sent, paper bound, without charge, cloth bound, on receipt of 20cents. Bulletin No. XII. Scientific Series No. 3. The Plankton of Lake Winnebago and Green Lake. CO. Dwight Marsh, A. M., Professor of Biology, Ripon College. 1903. Pp. vi, 94. 22 plates. Sent, paper bound, without charge; cloth bound, on receipt of 25 cents. In Press. Bulletin No. XIII. Hconomic Series No. 8. The Baraboo Iron Bearing District. Samuel Weidman, Ph. D., Geolo- gist, Wisconsin Geological and Natural History Survey. 2, BrenniaLt Reports. The Survey has published three biennial reports, which relate to admin- istrative affairs only and contain no scientific matter. First Biennial Report of the Commissioners of the Geological and Nat- ural History Survey. 1899. Pp. 31. Second Biennial Report of the Commissioners of the Geological and Natural History Survey. 1901. Pp. 44. Third Biennial Report of the Commissioners of the Geological and Nat- ural History Survey. 1903. Pp. 35. 3. HypRoGRAPHIC Maps, There have been prepared hydrographic maps of the principal lakes of southern and eastern Wisconsin. This work is in charge of L. 8. Smith, Assistant Professor of Topographical Engineering, University of Wis- consin. The following maps are now ready: Size of Plate, Scale, Inches Contour In- Inches. permile. terval, Feet. NOME lee Wake Genevaacsscesn cn sske cece.) oe ba OLS 2 10 INove2h lichartialcons ies Se eae 15.5x13.1 D 10 Non aoueeluaker Beulah ceanseoc eres a eosuueerax2040 6 10 No. 4. Oconomowoc-Waukesha Lakes..... 29.8x19.1 2 10 No. 5. The Chain of Lakes, Waupaca..... 21.7x20.6 6 10 No. 6. Delavan and Lauderdale Lakes.... 22.5x16.8 4 10 INO deli GLreeMiluakon on anise ners Gh ROSS 26.0x17.8 3.2 20 Now 8c) ake! Mendotaciis ccs sone sce ee 23.7x19.5 6 5 NO os) BieiCedanlWakers cms sooce ences 18.0x13.5 2.9 10 No. 10. ake Monona. ea 17.6x17.3 4 5 In all of these maps the depth of the ‘lakes is indicated by contour lines, and by tints in all except No.1. They are sent on receipt of 15 cents each except Nos. 4 and 8, for which 20 cents are required. They may be had either mounted in a manilla cover, or unmounted. All correspondence relating to the survey should be addressed to K. A. Bireez, Director, Madison, Wis. 8 SMITHSONIAN INS TION LIBRARIES UN 00048 3859 enonprhar-"525+}- aS aia?