LIV 3005 Xivccpool nPannc JBioIooy) CoimntttcW L.M.BL. MEMOIRS ON Typical British Marixe plants o^- Animals EDITED j;y ir. A. Herdmax, D.Sc, F.R.S. IX. CHONDRUS BY OTTO V. DARBLSHIRE, Ou'cii.s College, Manchester. L (With 7 Plates) Price Half-a-Ckown. LOXDOX AViLLlAM.', dv' XOKGATE, JlLV, 1902. HARVARD UNIVERSITY. LIBK ARY OF THE MUSEUM OF COMPARATIVE ZOOLOGY. (Jo oaaj^Xx' L.M.B.C. MEMOIRS. IX. CHONDRUS. NOTICE. The Committee desire to intimate that no copies of these Memoirs will be presented or exchanged, as the prices have been fixed on such a scale that most of the copies will have to be sold to meet the cost of production. The Memoirs may be obtained, post free at the nett prices stated, from Messrs. AYilliams and Norg-ate, 14, Henrietta Street, Covent Garden, London. Memoir I. Ascidia — published in October, 1899, GO pp. and five plates, price 2s. „ II. Cardium — published in December, 1899, 92 pp., six plates and a map, ])rice 2s. (Jd. ,, III. Echinus — published in February, 1900, 36 pp. and five plates, price 2s. ,, lY. Codium — published in April, 1900, 2(5 pp. and three plates, price Is. (Id. „ y. Alcyonium — published in January, 1901, 30 pp. and three plates, price Is. 6d. ,, VI. Lepeoplitbeirus and Lerna^a — published in March, 1901, 6'2 pp. and five plates, price 2s. ,, VII. Lineus — published in April, 1901, 40 pp. and four plates, price 2s. ,, VIII. Pleuronectes — published in December, 1901, 260 pp. and eleven plates, price 7s. ,, IX. Chondrus — now ready (July, 1902), 50 pp. and seven plates, jirice 2s. 6d. l,tvcrpool flDai'lnc Biolocjy (loinnuttcc. L.M.B.C. MEMOIRS ON Typical British Marixe Plants e- Animals EDITED nv ir. A. Herdman, D.Sc, E.R.S. IX. CHONDRUS OTTO V. DARBISHIRE, Ozcens Colhm, Manchester. (With 7 Plates) Price Half-a Ckowx. LONDON Williams & Norgate July, 1902. EDITOR'S PREFACE. The Liverpool Marine liiology Committee was constituted in 1885, with the object of investigating the Fauna and Flora of the Irish Sea. The dredging, trawling, and other collecting expeditions organised by the Committee have been carried on inter- mittently since that time, and a considerable amount of material, both published and unpublished, has been accumulated. Fifteen Annual Reports of the Committee and five volumes dealing with the "Fauna and Flora" have been issued. At an early stage of the investigations it became evident that a Biological Station or Laboratory on the sea-shore nearer the usual collecting grounds than Liverpool would be a material assistance in the work. Consequently the Committee, in 1887, established the Puffin Island Biological Station on the North Coast of Anglesey, and later on, in 1892, moved to the more commodious and convenient Station at Port Erin in the centre of the rich collecting grounds oi the south end of the Isle of Man. A new and larg-er Biolog-ical Station and Fish Hatchery, on a more convenient site has now been erected, and will, it is expected, be opened for work next month, July, 190'2. In these fifteen years' experience of a Biological Station (five years at Pufhn Island and ten at Port Erin), where College students and young amateurs form a large proportion of the workers, the want has been frequently felt of a series of detailed descriptions of the structure of certain common typical animals and plants, chosen as representatives of their groups, and dealt wilh by specialists. The same want has probably been felt in other similar institutions and in many College laboratories. VI. Tlie objects of the Committee and of the workers at the Biological Station have hitherto been chiefly faiinistic and speciographic. The work must necessarily be so at first when opening np a new district. Some of the workers have pu1)lishod papers on morphological poinis, or on embryology and observations on life-histories and habits : but the majority of the papers in the vohimes on the " Fauna and Flora of Liverpool Bay " have been, as was intended from the first, occupied with the names and characteristics and distribution of the many different kinds of marine plants and animals in our district. And this faunistic work will still go on. It is far from finished, and the Committee hope in the future to add greatly to the records of the Fauna and Flora. But the papers in the present series are quite distinct from these previous publications in name, in treatment, and in purpose. They are called the " L.M.B.C. Memoirs," each treats of one type, and they are issued separately as they are ready, and will be obtainable Memoir by Memoir as they appear, or later bound up in convenient volumes. It is hoped that such a series of special studies, written by those who are thoroughly familiar with the forms of which they treat, will be found of value by students of Biology in laboratories and in Marine Stations, and will be welcomed by many others working privately at Marine Xatural History. The forms selected are, as far as possible, common L.M.B.C. (Irish Sea) animals and plants of Avhich no adequate accoimt already exists in the text-books. Probably most of the specialists who have taken part in the L.M.B.C. work in the past will prepare accounts of one or more representatives of their groups. The following have already promised their services, and in many cases the Memoir is already far advanced. The first Memoir vu. appeared in October and the second in December, 1899, the third in February, and the fourth in April, 19U0, the tifth ill January, the sixth in March, the seventh in April, and the eighth in December, 1901, while this ninth one will be ready in July, 1902, and a tenth later in the summer ; others will follow, it is hoped, in rapid succession. Probably Arenicola, Patella, Myxine, and the Oyster will be ready next. Memoir I. Ascidia, W. A. Herdman, 60 pp., 5 Pis., 2s. ,, II. Car])ium, J. Johnstone, 92 pp., 7 Pis., 2s. 6d. ,, III. EciiiNTs, H. C. Chadwick, 86 pp., 5 Pis., 2s. ,, IV. CoDiuM, E,. J. H. Gribson and Helen Auld, 26 pp., 3 Pis., Is. 6d. ,, V. Alcyonium, S. J. Hickson, 30 pp., 3 Pis., Is. 6d. ,, YI. LEPEOPiiTnEiRUS AND Lern^a, Andrew Scott, 62 pp., 5 Pis., 2s. „ YII. LiNEUS, 11. C. Punnett, 40 pp., 4 Pis., 2s. ,, VIII. Plaice, F. J. Cole and J. Johnstone, 260 pp., 11 Pis., 7s. ,, IX. CiiONDurs, 0. V. ])arbishire, 50 pp., 7 Pis., 2s. 6d. Arenicoi a, J. H. Ashworth. Myxine, F. J. Cole. BucciNUM, W. B. Randies. BuGULA, Laura li. Thornely. Patella, J. R. A. Davis and H. J. Fleure. Oyster, W. A. Herdman and J. T. Jenkins. OsTRACoD (Cytheke), Andrew Scott. Denbronotus, J. A. Clubb. Peridinians, G. Mvirray and F. G. Whitting. Zostera, R. J. Harvey Gibson. Himanthalia, C. E. Jones. Diatoms, F. E. Weiss. Fucus, J. B. Farmer. Vlll. IJoTRYLLoiDES, W. A. Heidiuaii. Cuttle-Fish (Eledone), W. E. Hoyle. Calanus, I. C. Thompson. xlcTiNiA, J. A. Clubb. Hydroid, E. T. Browne-. Calcareous Sponge, E. Hanitsch. Antedon, H, C. Chadwick. Porpoise, A. M. Paterson. Gammarus, M. Cussans. In addition to these, other Memoirs will be arranged for, on suitable types, such as Sagitta (by Mr. Cole), a Cestode and a Turbellarian (by Mr. Shipley), Carcinus, an Isopod, and a Pycnogonid (probabl}- by Dr. A. R. Jackson). As announced in the preface to Ascidia, a donation from Mr. F. H. Gossage of Woolton met the expense of preparing the plates in illustration of the first few Memoirs, and so enabled the Committee to commence the publication of the series sooner than would otherwise have been possible. Other donations received since from Mr. Gossage, from the Publications Committee of the Victoria University, and from Mrs. Holt, are regarded by the Committee as a welcome encouragement, and have been a great help in carrying on the work. W. A. Herdman. University College, Liverpool, June, 1902. L.M.B.C. MEMOIRS. No, IX. CHONDBUS. BY Otto V. Darbi shire, Owens College, Manchester. Contents, PAGE I. Introduction 2 Introductory remarks. The collection of material and its preparation for the herbarium and the microscope. II. Chondrus crispus (L.) Stackh 7 A. External morphology of the vegetative organs 7 B. Anatomy and histology of the vegetative organs 10 1. Anatomy of the shoot 10 2. Anatomy of the root 15 3. Histology of the shoot IG 4 . Histology of the root 20 C . Physiology of the vegetative organs 20 D. The reproductive organs 22 1. The nemathecium 23 2. The spermophore 2G 3. The carpophore 27 E. Ecology 29 III. Concluding Eemahks 34 General summary 35 Conclusion 37 Description of the Plates ...:.,; 3'J B I.— IXTRODUCTIOX. The Rhodophyceae are a very distiuctive class in tlie Eupliycese or Algse, wliicli form a sub-division of tlie Thallophyta. They are separated from tlie otlier classes of the Eiiphycere by their reddish or violet colour. This colour is produced by tbe green chlorophyll being obscured by a red colouring matter, called Phycoerythrin. The RHonoi'iiYCKA.ic embrace two su])-classes, namely, the ]?AXGiALES and the Floride.e. The representatives of the former have very simple and undiiferentiated filamentous or membranous multicellular bodies. The sexual organs are extremely simple. The Florideae have multicellular bodies, consisting usually of much-branched rows of cells, which often form plants of good size and firm structure. To the sub-class Floridese belongs the subject of this memoir, Chondrus crii^pus, the Irish Moss. With the exception of nine genera, five of which are confined to freshwater, the Floridese are exclusively marine plants. The arrangement of the natural orders of the Floridere into series is dependent on the various methods by which the fruit develops after the fertilisation of the female organ. It is unnecessary to refer to the subject in detail here. It must suffice to say tliat the natural orders are arranged in four series, namely, the Nemalionales, the Gigartiiiales, the lihodymeniales and the Cryptonemiales. The natural order to which Chondrus belongs is that of the Gigartinacepe, one of the Gigarlinales. The only other order of this series, the Acrotylaceae, differs from the Gigartinacese in the arrangement of the asexual spores in their mothercell. The tetraspores of the latter are formed by cruciate, those of the former by zonate, division. The natural order Gio'artiiiaceiT' iiicliules nine British ft'enera. namely, ('hoiuJri\ii. (iii/ajiiiKi, Plnjllophord, Stcno- {iraninw, Gi/»nioii<)n(irti.s, Alinfeltia, Actinococcus, Callo- pJij/llis and lastly Ccdli/iuciiia. Of these the representa- tives are all fairly well developed plants, with the excep- tion of the species belonging- to the genus Aefinococcus. One of these has been shown to lead a parasitic life on Pli j/U<>p)i ora Brod 'ue i. The genera Choiidriis and Gif/artina differ from the remaining members of the Gigartinaceae in their structure. They show internally a very well marked hyphal arrange- ment of the cells — their internal tissues in the younger plants consisting of fairly loose filamentous cells. The central tissues of the othei' genera are, with the exception of Aetin<)eoccu:<, far more compact and psendoparenchy- niatous. The species of Chondnis have a flattened plant l)ody or thallus. The carpospore^ in the fruit or cystocarp are not surrounded by any special fibrous integument. The latter is one of the distinguishing features of the species of the genus GIf/arfina. ('ho)idriis crispiis is the only species of its genus occurring in British waters, and therefore in the L.M.B.C. district. Quite a large number of varieties are dis- ting-uished, but I have not referred to these in this memoir, as I consider their recognition to be of no general value. The s:^nus Chondnis was founded bv Stackhouse — the name crispiis was given to the species by Linneeus. The latter, however, placed the species in the genus Futiis, to which he referred almost every seaweed. Stackhouse removed the species, and gave it a place in the genus Ghondrus, where it has remained ever since. Its name therefore runs thus: ('lioiidni>i cri^jnis (L.), Stackh., or, according to a certain number of German Algologists, Gfiondrus cr/spiis, L. sp. They wish to indicate merely tlie autlinr of the species, the " sp." in this case implying that LiiinsBUS was responsible for the specific name only. Chondrus crispus grows very plentifully along our sea- coast, as long as the sea bottom is rocky. It is usually left dry at low tide, when it can be easily obtained. It much resembles Gigartina inammillosa, from which plant it is, however, easily distinguished wlien in fruit, but not so easily when sterile. Gigartina mnmmiUosa nearly always has the margins of the thallus lobes slightly rolled in. CJiondrus crispus will probably be recognised fairly well by referring to our Plate I. It should be carefully separated from Gigartina mamniiUosa, Gymnogongriis nor- vegicus and PJtijllopltora menihra)iij'oUa. A few remarks may not be out of place here on the collection of material and its preparation for the herbarium and the microscope. All material collected for an examination of the external morphology or the internal structure should be gathered fresh. Plants thrown up after a gale are usually in poor condition. A glass jar should be taken oai every shore collecting expedition, into which the plants should be put, immersed in sea water, as soon as they have been removed from the substratum. The latter can be done with a knife, or a bit of tlie ]ock may be chipped off. The water in the jar should not bo allowed to get too warm. The height at which the plants were collected should be noted, also the nature of the substratum, and also whether the plants were growing exposed on the bare face of the rock or in pools. In the laboratory the algre sliouhl be kept in a dark, cool place. It is usually sufficient to put the jars under the working table. Proper cultures may be set up, and kept for many years, by putting a few seaweeds in a good sized jav, keeping the temperature of the water low and exposing only to the feel)lest light. To examine the external morphology of an}^ alga, the specimens should he placed in a shallow white dish, and again kept covered over with sea water. ]{eforo mounting- specimens for the lierharium they should he soaked for a few minutes in fresh spring water to remove as much as possihle of the common salt ])resent. The pliyccerythrin of the Floridese being- soluhle in fresh water, too long an immersion in fresh M'ater would destroy their colour. After heing washed the plant should ])e put between sheets of blotting- paper, or better, some kind of filter paper. I find that so-called common German filter paper answers vevj well indeed. This paper is very much tougher than most kinds of blotting paper, and also a good deal cheaper. A board is put on to the top of the drying paper, and this is weighted down by a few not too heavy stones. In the case of certain algae, which are more delicate than C^/io/idrus crispifs, it will he necessary to fioat them out in fresh water on to a piece of white foolscap paper. They will usually be found to stick naturaUv to the paper they have been mounted on. To prevent their sticking to the filter paper some fine muslin is interposed between them and the drj'ing paper. When the plants have been pressed for a few days, with a daily change of the paper and muslin, the weights may he removed for twelve hours to allow the air to circulate more freely for drying purposes. All the specimens should he carefully labelled with the name, locality, date, and any short remarks which may seem necessary. To examine any material unde/ the microscope, it should be cut as fresh as possihle, and examined in sea water. Transverse and longitudinal sections of every "part of the plant should he cut with a razor, with or without clamping the material in pith. The section should then be mounted and examined in sea water. Fresh spriiifr water or g^lyceriue kills tlie tissues very rapidly, and the former more particiilarly causes a great swelling u]) of the cell walls, whereby the appearance of the tissues becomes very much distorted. Iodine should frequently be employed to test for the presence of starch. For this purpose dissolve some crystals of potassium iodide and some of iodine in water. Permanent preparations may be made by putting a freshly cut section into dilute glycerine, and thence into glycerine jelly. Sections may be stained in a solution of lirematoxylin ( 1 per cent, solution in water), and then mounted in glycerine jelly. When stained, sections can also be permanently mounted in Canada balsam. To this end they should, after staining, be dehydrated in absolute alcohol, and after replacing the alcohol by xylol, they are mounted in Canada balsam, which has previously been dissolved in xylol. If it is intended to preserve some material in a bottle for futui-e examination, it should be fixed iu a 1 per cent, solution of picric acid in water. The material may remain in this solution foi' a few hours, and is then washed in •3(1 per cent, alcohol, till the latter no longer becomes yeUow. Then remove it to TU per cent, and finally to 90 per cent, alcohol for })re:ierving. Some glj'cerine (about '-io })er cent.) may be added, thus preventing the specimens getting too brittle. In order to cut sections with the microtome, the portions of the plant to be cut must be enibeddeil in paratfiu. They should be dehydrated in absolute alcohol, left in cedar- wood oil till they are quite transparent, and then trans- ferred to paraflin at 55° C. They may be cast iu a block after about two hours. Permanent preparations are, however, useless to a student, if s'milai sections have not been previously examined in a fresli condition. The student sliould, fui'tlierniore, make drawings of tlie sections before they are permanently mounted. A permanent preparation of an alga is often a very poor guide to the condition of things obtaining in the living plant. A good drawing, or even a careful sketch of a fresh section is at a later date generally a far better reminder of what was seen in the living plant than an old glycerine preparation. It is a useful plan to make the drawings on loose sheets, and insert them in the herbarium with the dried specimens. It is, of course, necessary to carefully label all slides at once. This prevents any possible confusion to which a later labelling bv memorv nearlv always leads. "b II.— CH0NDRIT8 CRISPUS (L.) Rtackh. The species C/tonJn/s crispus has now been definitely recognised from the introductory description given in the preceding part of this memoir. AVe can theiefore proceed to the more detailed description of the plant. A. — -The External Morphology of the Vegetative Orgaxs. The plant body of C/ioiuJrus n-isjtns shows a very dis- tinct morphological differentiation into two parts — namely, into a shoot and a root. Nevertheless it is cenerallv referred to as boino' a bul liitle difl^erentiated thallus, the dilfereutiatioii not being of ([uito the same degree and kind which we meet with in the higher plants. But it is possible to distinguish very clearly a root from a shoot. The latter alone bears the reproductive organs. The Root is mainly an organ of attachment. In this respect our alga resembles most of the higher aquutit 8 plants. Tlie root is a flat and not very thick plate of tissue, wliich adlieres very closely to the rocky substratum. No food material apparently is absorbed from the latter. There is no reason, however, why the exposed portion of the attachment disc should not extract some food material from the surrounding- sea water. It is coloured a faint red, and it may therefore assist in the process of assimila- tion, but only to a limited extent. It is, however, an important organ for the storage of food material. It grows in circumference along its margin, covering every- thing that may happen to be attached to the rock and extending into any small holes and crevices in the latter, thereby acquiring a very irregular shape (PI. III., fig. 9). By this means the whole plant gets very firmly attached to the sea l)ottom (see PL I.) From the fiat root disc arise the numerous upright SHOOTS. These are at first undivided and more or less cylindrical in transverse section. But they soon become flattened, and when they have attained a height of 1*5" (•'} cm.), tliey are always divided. The full grown shoot is as a general rule more or less flattened throughout. Its lowest end, however, just where it joins the root organ, may be cylindrical, but it soon becomes flattened, even if only slightly. With its hrst division the shoot becomes very much flattened and very thin. The branching of the leafy portion of the shoot is throughout a very regular kind of forking. No midrib is formed, the texture of the shoot being fairly uniform and almost leathery throughout. The shape of the separate shoots is very simple and very uniform amongst the individuals even of very different localities — be they broad or narrow forms. A fairly long and undivided stalk can be distinguished from the much divided frond. In the taller plants, found chiefly at low 9 tide, the stalk is very loiii;- aiul very stron,t;- (PL I., iigs. 1, 2,3). Ill the forms found hig'her up on the seashore, and there- fore more frequently and longer exposed, the whole plant is smaller and the stalk proportionately shorter, the frond, however, is often broader (tig. 4, 5). All forms agree in showing a repeated and fairly regular bifurcation of the frond into flat lobes, which graduallj' g-et broader at their further ends. A small indentation between two projecting points at the tips of the lobes indicates where the next bifurcation will take place. The segments of the frond not only become broader, but also thinner in texture. The broadening out of the lobes causes an overlapping of the segments. The colour of the frond varies from dark red to light pink, and a brownish colour with a dash of pink. The following are some of the measurements taken on our plant. The largest specimens gathered at low-water mark are as much as 15-17cm. (G-T") high, with a frond 12*5cm. (5") across (fig. 1). The stem in such a case would measure about ronuii (rV ') in thickness. At higher water marks the plants are found in pools only, and not on the bare rock, as at the lower tide marks. In the former case thev are much smaller in height and grow in verv close, low tufts. They are, however, usually propor- tionately very broad (fig. 4, 5). The functions of the shoot are best expressed by the two words assimilation and reproduction. The shoot probably is extremely active in absorbing food material from the surrounding water. This, however, is a point about which we know practically nothing of a definite nature. It is very difficult to keep marine plants in culture, because we do not know what the essential features of the conditions are which obtain in their natural haunts. Algae may be kept for a very long time in fairly dark and cool rooms 10 in even small glass jars. As a lulo, liowover, tliey grow very slowly and remain sterile, the conditions heing pro- bably very imfavourable. b. axatomy axd histology of the Vegetative Organs. 1. — Anatomy of the Shoot. The young upright shoot of Chondrus crispus shows a differentiation into several tissues, which are, however, not very easy to separate at the points where they pass into one another (see PI. II.) The centre is occupied by very much elongated and comparatively narrow cells (fig-T). These central cells lead to a tissue further out of shorter and stouter cells, from which arise the regular rows of external cells, easily distinguished by their red contents. There is no morpho- logical differentiation of these tissues such as we get in the bodj' of a higher, vascular plant — the differentiation here being of a purely physiological nature. The external cells, distinguished by their dark red colouring form the " assimilating system," the large stout ones next inside form the system of " collecting cells," the central cells form the " conducting tissue." The whole arrangement is based on the assimilation, collection and conduction of food. The assimilating cells have been called the cortical layer, the two other tissues the outer and inner medulla respectively. We will employ the nomenclature based on the physiological function of the respective tissues, although the other terms, cortex, inner and outer medulla, are equally good. The tissues just mentioned are seen at their best and in their most characteristic condition a short distance behind 11 the youngest part of the shoot. The youngest or most actively growing- part of a shoot is found at the end furthest away from the hasal attachment organ. A longitudinal section of a young frond should now be cut at right angles to its surface, and rather near a median longitudinal line. The material should he fresh and the sections should be mounted in sea water. These should be examined first, but others can also be examined after being mounted in glycerine (50 per cent, solutiou in water) or glycerine jelly (fig. 7). The Central Conducting Cells will be found to be elongated in a longitudinal direction. They are fairly narrow, and they possess fairly thick walls. The peculiar nature of the walls becomes very apparent when a section is mounted and examined in fresh spring water. In this case, owing to the rapid absorption of water by the cell walls, the sections rapidly curl up. This central tissue of much elongated cells resembles more a strand of interwoven filaments than a close paren- chymatous tissue. ]iy this Chondrus crisini.s may, as already pointed out, be distinguished from the species of several allied genera. But it has this feature in common with Gigartinu mtunillu.-ia. The cells of the conducting tissue are connected with one another at certain points. These points become very evident if the cell walls of a section have been allowed to swell up in water or dilute glycerine. The cell walls encroach on the cell cavity, leaving only a narrow canal of varying length leading apparently from one cell to another. A hue wall, which does not swell up, is stretched across the canal, thus forming a pit, as we find it in the higher plants. The pit membrane probably allows of the cytoplasm of one cell communicating with that of the other. On each side of this pit is a small cap, consisting 12 of M-liat ap])ears to be coao-alated cytoplasm. The struc- tiuo of tlie ])it will be referred to again, when discu.ssino- the histology of the shoot subseciueiitly. Connected with the central elongated cells of the con- dncting tissue are the Collecting Cells. These are much shorter than the central cells, and as we pass further out they diminish still more in size. They form a lather closer tissue than the conducting cells, and they are extensively connected by pits, with or without the above- mentioned protoplasmic caps, with any of the neighbour- ing cells they may come into contact with. The nearer we come to the outside the more regularly do they come to lie in rows. Finally there arise from them the very regular rows of Assimilating Cells, which run parallel to one another, but are curved upwards and outwards at a certain very definite angle with regard to the longitudinal axis of the whole shoot. The assimilating cells possess numerous pits, which are however all destitute of caps. The whole body of Chondrus crhjms consists of a com- plete system of veiy long and very much branched liyphse. The assimilating cells f()]'ni the a])ical branches of these liyplne. As a general rule the divisions in these threads Avill take place at right angles to the longitudinal axis of each cell row. l^ut there is evidence to sIioav that some of the divisions are more or less at rio-ht ano-les to this direction. Hyphal tissue of this kind has been distinguished as plectencliyma. The iilamentous nature of the tissues l)ecomes very apparent if the growing point of a frond is examined in a longitudinal section, when one can see spreading out in a fan-shaped fashion the hyphte of all the three tissues (PL IL, tig. 6). In transverse section the cells of a young plant differ little in appearance from what is seen in longitudinal section, except that the conducting cells appear rather 18 round, but still slio-litly oval in outline. In the case of the ilat frond, they are usually elongated in a transverse direction and ])arallel to the two flat surfaces. There is no diiference to he noted in the other tissues. I have already referred to the growing point. It is that part of the plant where the formation of new cells i-i going on most actively, but it is, strictly speaking, not the only part of the plant which is groAving. Cell division is going ou very rapidly in this region, as may be seen by looking at the size of the cells. The formation of new cells is, however, not confined to this region, but is also going on, though probably less rapidly, at the tips of nearly all the assimilating cell rows. The innermost cells of these rows gradually become collecting cells, and new rows of assimilating cells are formed by branching. Xew cells may also, though rarely, be formed by short tube- like cells growing out from older condiicting cells. Thus far the formation of new cells, as pait of the process by which Chondrus crlspus grows, has been described. The growth in length of the shoot is brought about by the cells of the conducting tissue becoming more elongated, by the collecting cells becoming larger and in the end passing into conducting tissue, finally by the assimilating cells gradually passing into the collecting cells and new assimilating cell rows being formed hj the branching of the older ones. The cells of the conducting tissue measure about 8-10/x in length at a point about lOOyw back from the shoot apex, at further intervals of 100/x they increase on the average to 10-14^, 20^, 30-40//, 50^, being finally 80// at a distance of about 800// from the apex. The collecting cells, with a measurement of 4-8// in their longest diameter at a distance of 100// from the apex, increase at intervals of 100// to 8-10//, 10-12//, 14 and 20//. This mnv be taken as their greatest diameter, for after this tliey woiihl he reckoned part of the condiict- iug tissue. The assiniih\tino' cells vary very litth^ iu diameter, heino- about 4-6 X 3-4,a near the apex, and rarely rising aboye 8 X 8-4/x in the lowest regions just aboye the basal disc. Their longest diameter is generally parallel to the longi- tudinal axis of the Ayhole vow of cells. The increase in thickness of the lower regions of the shoot is brought about not by the addition of thick layers of assimilating tissue, as is the case with PhyUoplioi-a Ih-odid-i. The assimilating layer in Citondi'us is 20-25;x deep in a tlat frond of about 350/x in thickness, but in a frond which was 840/x thick, tlie thickness of the assimi- lating layer was only 25-30/x. The increase in thickness is in fact due to the assimilating cell rows formine- new cells at their tips, whilst their inner cells gradiu\lly pass into the collecting cells, and these gradually pass into the conducting cells. The increase in thickness is noticeable in the central tissue only to any exfent. It is taking place here at the expense of the outer laj-ers, which are, how- eyer, continually being renewed by the formation of new cells at the tips of the rows of assimilating cells. It is probable that a good deal of sliding of cells occurs as the growth in length takes place. The increase in length is probably caused not by the central cells actiyely growing in length, but by their being drawn out passiyely during the active lateral extension of the assimilating laj'er. But frecjuent longitudinal slits haye failed to indi- cate in what way tension is distributed in the tissues. The central tissue is yery well separated by the filamentous nature of its constituents in the younger parts of the shoot, ])ut in older parts it assumes more and more a pseudoparenchynmtous ap})earance. By this change the 15 tissues beconip firmer and the slioot, as a whole, is there- fore much stiengthened in these ohler parts. The walls of the conducting- cells are very much thicker and firmer in the older part of a shoot than in the younger one. 2. — Anatomy of the Root. The basal attachment organ, or the root part of the whole plant, does not show any differentiation into the three tissues met with in the shoot. It forms a flat plate of tissue, from which the upright shoots arise. Its out- ward form depends entirely on the nature of the sub- stratum to which it is attached. It is thickest, however, at the points from which the upright shoots arise, and it becomes thinner towards its margin. The lower surface of the attachment organ penetrates into all the numerous crevices of the rock in order to firmly fix the plant. The cells nearest the substratum, forming what might be called the " Attachment Layer," are of very varying shape, and are very irregularly arranged. Their position and shape depend on the varying minute nature of the substratum. They have thick Avails, and form a layer of cells touching the surface of the rock which may be two or three cells deep. But in cases where they have pene- trated into and completely filled out some small hole, they may form a mass of thick walled cells, connected only by small but very firm strands of much elongated cells to the main mass of the root (fig. 9). The greater mass of the root tissue proper is made up of very regularly arranged rows of almost square cells, which run more or less at right angles to the surface of the whole attachment disc. These rows of cells are, strictly speaking, always slightly curved. At the point where a shoot arises they have a convex side turned towards the lower end of the shoot, passing finally into and adopting 16 the curve of tlie assiniilatino- filaments of tlie shoot. Tlieu again, near the periphery of the whole attachment organ, where the latter is still very thin, the curved rows of cells have their convex sides turned towards the margin. Seen in surface view the cell rows are observed to o-row out in a fan-shaped fashion towards the margin. The growth of the rows of cells is here mainly, if not exclusively, apical. Transverse divisions in the apical cells are common, longitudinal at the most extremelv rare. The upright rows of cells will be seen to be completely undivided (fig. 10). The whole attachment disc grows in circumference by the formation of new rows near the margin. But it grows in thickness by the elongation through apical cell forma- tion of the old cell rows. The cells once formed do not change their form and size to any great extent, as soon as they have attained their full size, about o to 4 cells behind the tips of the filaments. The whole plant is covered b}' a protective membrane, which is not very thick in older shoots, but is very distinct near the apex of a shoot. It becomes a very deep layer in certain parts of the basal attachment organ. On either side of the insertion point of an upright shoot, it is usually very well developed. It is here produced by successive layers of wall substance being separated off from the apical cell of each filament (Pi. III., fig. 10). The cells of the attachment organ are usually full of starch. They are reddish in colour, but the latter is not as dark as in the assimilating cells of the upright shoot. 3. — Histology of the Shoot. The cell walls of the central cells are not very thick when examined fresh and in sea water (PI. II., fig. 8). They do, however, swell up very much in spring water 17 or in dilute o-lvcerinp. One can disting'uisli tliree layers in llie cell walls, which are best differentiated in case of condiictina' cells when a lone'itudinal seetiou is stained in hasmatoxyliii and mounted in dilute glycerine. The middle lamella is seen to be fairly thin, but can nevertheless be well made out. It is common to all cells. Each cell is surrounded by a wall, which lies immediately inside the middle lamella, and dees apparently not swell up very much in water. Then follows an innermost layer, which is in its turn lined by the protoplasm. This layer shows a very distinct concentric stratification, and is apparently most affected by fresh water. It swells up very much indeed. AVith reg-ard to the protoplasm inside the cell wall very little can be said. It consists of the cytoplasm, and con- tains a roundish nucleus, one or more plastids, starch and vacuoles. The cyptoplasm never occupies a ver}^ large space of the cell cavity. The latter is usuallj^ taken up by one or more large vacuoles. The cytoplasm of the larger central cells consists merely of a very fine mem- brane, which lies between the vacuole and the cell Avail. Xo fine partitions formed by cytoplasmic lamelUe can be seen stretching across the vacuoles. In the outer collecting, and still more in the assimilating^ cells, the cytoplasm appears as a slightly frothy liquid. Fine lamellae are seen to stretch across the vacuoles. It must, however, be understood that the frothy appearance of the cytoplasm so easily seen in many algro affords no indication as to its ultimate striicture, as is so often supposed. It has already been mentioned that the large central conducting cells are in communication with one another by means of pits. The pit membranes are thin portions of the wall which do not swell up in water or glycerine. C- 18 Their position, tlierefore, becomes very apparent if we allow the other portions of the wall to swell up. The innermost of the three layers, of which the cell wall is composed, does not apparently take any part in the formation of the pit, except by its being interrupted at these points. The large pits of the central conducting cells have on either side a cap, which is most likely of protoplasmic origin. The cap is a short cylinder, the one open end of which (fig. 12, IS) overlies the pit membrane, with which it is co-extensive. At its otiier end the cap is closed, a small depression being noticed in the centre of the wall. It is at this depression that the cytoplasm is most firmly attached to the cap. This depression corresponds with the thinnest portion of the pit membrane. In younger cells nearer the growing point the cajjs on the sides of the pits in the central tissue are not so marked. It is from observations made in such parts that the protoplasmic origin of the cylindrical caps is made likely. The sides of the cylinder are seen to be continuous with cytoplasmic strands. They seem, in fact, to be hardened portions of the cytoplasm. Giving to the complete absence of any hard woody tissue in the thallus of Choiidrns crispn!^, it seems very probable that these hard caps have the important function to per- form of preventing the collapse or closing up of the open- ing on either side of the pit. The cells of the collecting tissue usually have smaller pits, which may or may not be devoid of any cap-like structures. The pits connecting the assimilating cells are usually quite unprotected, but nevertheless form clearly marked thinner portions in the separating cell wall. The Plastids met with in ClionJrus crispus occur in two different forms, namely, as rhodoplastids and as leuco- 10 plastids. Both these are, however, only modifications of the same organ. The Rhodoplastids are best developed in the assimilating cells (fig. 14, 15). They are seen here to be of a dark red colour. The red colour is made up of a mixture of chloro- phyll and phycoerythrin, the latter completely obscuring the former. The latter may also be extracted by sub- mersion in fresh water for some time, preferably in waim water. The plant will remain green, the chlorophyll being insoluble in water. The outermost cell of the assimilating filament has a very small rhodoplastid. The latter is represented by a very much reduced flat structure, which fits into the outer end of the oval shaped cell. The remaining part of the cell appears colourless. The other assimilating cells possess very well developed dark red rhodoplastids. They form here cylindrical plates, which line two or three or even all the radial walls, and sometimes even the outer tangential wall. They do not form a closed cylinder, for they are open along one side. Each cell here contains only one rhodoplastid. The Ehodoplastids are well developed in these assimi- lating cells, but as you pass on to the collecting cells, thev srraduallv change. The red colour becomes fainter, they get drawn out and become very finely divided. When we get nearer to the conducting cells, the rhodoplastids have become almost invisible. A^ery finely divided narrow strands are seen of a very faint pink colour. These are the plastids. The fine strands are interrupted here and there by rather larger and more deeply stained masses. Finally in the most central of the conducting cells the finely divided rhodoplastids have disappeared, their place being taken by small roundish leucoplastids. These are almost colourless, but often show a very faint greenish 20 tint. These leiicoplastids, of which a great many are often found in each cell, have been derived from the typical rhodoplastid of the assimilating- cells. The Leiicoplastids of the conducting cells and the faintly coloured rhodoplastids of the coHecting cells are both very active in depositing starch. Starch is never noticed in the assimilating celts. The starch grains take the form of flattened discs. They stain brownish when treated with iodine. The florideau starch is slightly different in its reaction after treatment with iodine from the starch of the potato, the grains of which stain blu'^ with iodine. 4. — Histolog*y of the Root. The histology of the root calls for no special remarks. The cell walls do not swell up nuich with fresh water. The pits also are not of the same large form met with in the shoot. The cells of the root are found to be quite full of starch, which by its presence almost completely obscures the rhodoplastids. The root organ is clearh' red, but the red plastids are hardly visible. They are apparently finely divided, consisting of darker red masses, which are con- nected with one another by faintly coloured strands. C. — Physiology of the Vegetative Organs. TJnder the heading of Physiology, reference may be made to the functions of the three tissues of the shoot. It is, as already mentioned, to their supposed physiological function that they owe their names. The Assimilating Cells are obviously correctly named. Assimilation is conducted by means of the rhodoplastids. The fixation of carbon dioxide and the subsequent elabora- tion of complex organic from simple inorganic compounds 21 may be assumed to be g'oiug on throiigli the activity and under the influence of the rhodoplastids. Xothing definite however is knoAvn concerning- the importance and function of the phycoerythrin in the rhodoplastid. The rhodopUistids in the assimilating cells are on the whole well developed and of a dark red colour. The apical cells of these assimilating rows have, however, only a very small rhodoplastid each. This is a general rule, and it may be due to the fact that these apical cells are actively growing and dividing. The substances built up are apparently removed very rapidly to the next inner cells away from the assimilating tissue. This latter, at any rate, contains no traceable quantities of starch. The food substances are in fact pro- bably collected by the collecting cells from the outer layers, and are then passed on to the large conducting cells. They are then stored or passed up or down the shoot, according to the direction in which any part of the plant in need of food may draw them. A certain faint red colour may often be detected in the finely divided rhodoplastids of the collecting and of the conducting cells, but it is impossible to say whether it enables assimilation to be carried on. In the centre of the shoot the red colour has disappeared, and in place of one red rhodoplastid we get numerous very faint green leucoplastids. Starch is found very abundantly in the collecting and in the conducting cells. Both these tissues, therefore, probably act as storing tissues. In the root organ the cells are all found to be full of starch. The root is evidently a very important organ for the storage of food. It is not likely that assimilation is going on very actively in the root. The rhodoplastids are faint in colour and very finely divided. 22 The wliole structure of Chondriis crlspus is A'eiy typical for a water plant. No hard tissues and no special water conducting cells are found. The plant as a whole is not able to keep itself upright except when in the water. The arrangement of the tissues is such that the plant is flexible, but not very elastic. The shoot is bent to and fro by the waves and the tides, but owing to the substance being very tough the shoots are very rarely torn off the substratum. Cltondrus crisjnis, is, in fact, very rarely found in the entang-led masses of seaweed which are thrown on to the beach after a gale. D. — The Reproductive Organs. The reproductive organs of Chondrus crispus are fairly well known. Yegetative reproduction seems to play practically no part in the life of marine plants. If it does occur in isolated cases it certainly plays no important part in the general biology either of the red algee in particular or the sea in general. The power of reproduction is, in the case of Chondrus crispus, confined to special cells or spores. These may be produced asexually and sexually. In the former case, they are called " tetraspores." In the latter they are known as " carpospores," which are the ultimate products of the fusion of the male nucleus of a " sperma- tium " with the female nucleus of the "egg cell." This fusion — or process of fertilisation — has never actually been observed in our plant, but may safely be assumed to occur. The nemathecia, the organs which produce the tetra- spores, the antheridia giving rise to the spermatia and the procarpia which harbour the egg cell, are never met with on the same shoot. It is impossible to say from the 23 observations to hand as yet wlietlier the shoots bearing different reprodnctive organs are borne on the same root. It is highly probable, however, that they are not. 1. — The Xemathecium. The tetraspores are formed in great numbers in certain younger portions of the frond. They make their appearance during the winter months, probably from December to March. AVhen held to the light slightly oval but elongated dark spots may be seen near the apical and younger portions of the frond. These darker portions may be accompanied by a slight bulging out of the assimi- lating layers, but this is never very marked. Each dark part is a nemathecium, containing tetraspores (fig. 19). In a longitudinal or in a transverse section (fig. 20), through a nemathecium the dark colour of the latter is seen to be due to a dense and rather irregular mass of small round cells. These may be the finished tetraspores, or their mother-cells. Each mother-cell gives rise to four tetraspores — hence their name. The whole internal tissue of the nemathecium consists of irregular rows of cells, which on the one hand join on to the collecting and a few of the conducting cells, and on the other hand pass into the assimilating layers (fig. 21). It is, however, before they enter the latter that their cells swell up at the expense of the neighbouring cells, which have a large store of starch. When these cells have attained a certain size they divide into four cells each. They are, in fact, the tetra- sporangia or mother-cells of the tetraspores (fig. 22). The original cell-rows are at first easily made out (fig. 21), but gradually the cells by their growth exert a certain amount of pressure in all directions and the regularity of the cell rows is disturbed. The surrounding sterile cells gradually 24 g-ive up all their store of food material, and finally collapse almost entirely. The tissues never hreak down entirely, but they do get fairly loose AA-hen the spores escape on maturity. The division of the protoplasm in the spore mother-cell takes place by the formation of several walls, but always in such a way that the resulting- four tetraspores are arranged either in one jjlane round a common point, or in the fashion of a pyramid of four billiard balls, or in two pairs, the wall separating the two spores of one pair running at right angles to that of the other pair. The spores are said to have been formed by cruciate division. The tetraspore is, on its escape, found to be a round, non-motile and naked reproductive cell, wliicli soon after its escape is surrounded by a firm cell wall. It contains a large amount of food material, starch forming an im- portant constituent of the latter. The protoplasm of the spore is also seen to include a rhodoplastid. The latter is rather difficult to make out, owing to the large amount of starch present. It seems to be of the form met with in the old cells of the conducting tissue of the shoot. It consists apparently of larger and darker portions regularly distributed just inside the cell wall of the spore, and these are connected by fine strands. Fresh tetraspores, fixed with, iodine, were heated and mounted in glycerine jelly. They then showed the rhodoplastids — now quite green — ■ and their ramifications very well. "When it has escaped, the mature tetraspore is probably able to proceed to germination at oaice. How soon it starts and how rapidly it continues to grow in nature it is still impossible to say. Probably it starts very soon. The tetraspores have not the appearance of resting spores. By employing a method, which gave me good results when applied to the tetraspores of Acfinoeoccus siihcu- 25 faneus, the small parasite living on Pliylloplwra Tlrodicci, I was able to germinate some tetraspores of Choiulrus crispus. The latter were dredged near Kiel, in the Baltic, and sown in a sea-water culture in the Botanical Institute of that University. Small portions of parchment paper were first thoroughly soaked for a lengthy period, up to six hours, in running water, so as to remove any acid present. The pieces of parchment were of a size to he conveniently put on to a glass slide, and covered M'ith a large coverslip for purposes of microscopical investigation. These strips of paper were put on to the bottom of small glass troughs 2" X 3" X 6" being a convenient size. The troughs were filled with fresh filtered sea water, and kept in a cool and fairly dark place in the Laboratory. For the first two or three weeks constant attention must be paid to the condition of the water in the cultures. The water must be removed imme- diately on the appearance of the slightest milkiness, the outward sign of bacterial activity in connection with some dead organism. A number of cultures should always be set up, as some will always succumb to some adverse circumstance. A portion of a fresh frond bearing a nemathecium may be placed, as soon as obtained, on one of the strips of parchment in a culture. After a certain time the spores will be seen to have escaped, and to be lying about on the parchment. The frond may now be removed, the spores remaining in the culture. AYlien the spores begin to germinate the strips of parch- ment can be put on to slides and be examined with the microscope. They must be kept supplied with plenty of fresh sea water, and be guarded against too strong light. They may not be kept out of the cultures too long. A coverslip may be employed, but with great caution. 26 If the water in the cultures is once quite clear, it only wants adding to very occasionally. In tlie case of Chondrus crispus, I observed that the tetraspore underwent division without at first growing very much in bulk (fig. 27, 28). Then, however, after having formed a small heap of cells, which are all very much smaller than the original tetraspore, longish filaments seem to be formed (fig. 29). These consist at first of unbranched single rows of cells. Finally the commence- ment of the formation of flat plates has been observed, and in the end no doubt a normal flat attachment organ is formed, from which the upright shoots arise. I have not however been able to follow out the growth of the germinating tetraspore to this stage yet. 2. — The Spermophore. The spermatia or male cells are found on young portions of the frond. The latter are temporarily modified only for this purpose. Later on they evidently again take on the functions and the structure, of an ordinary vegetative shoot. They have been called spermophores (fig. -jO. 31). The spermophores of Chondrus crispus are small and narrow, slightly flattened leaves. They appear white owing to the fact that the rhodophistids of the assimilating layers are but poorly developed. They are •'i-4mm. long and barely Inim. broad. The general structure of the spermophore does not difi'er from any ordinary young portion of the thallus. The difference lies in the nature of the last few cells of the assimilating filaments. The last two or three cells appear to be colourless owing to the rhodoplastid, though present, being very much reduced. These two or three cells together form an antheridium, or male organ. The last cell of the row, the spermatangium, gives rise to one 27 spermatiiim, or male cell. This escapes as a colourless, small round cell, devoid at first of any cell wall, with a diameter of 4-5m. It is non-motile. A fragment of a plastid seems to he present in the spermatium, but this is not revealed by any appearance of colour. When the spermatia have escaped they cease developing any further till they come in contact with the female organ or carpogonium. The antheridia form a layer, which extends over almost the entire surface of the spermophore, hence the white appearance of the latter. The spermatia are found to be mature between October and December. 3. — The Carpophore. The development of the female cell of Chondrus crispus has not yet been made out properly. The following account of its development and structure is based, there- fore, on the few established facts, and on our knowledge concerning the state of affairs in nearly allied genera. Certain portions of the upright fronds take on the function of carpophores, which carry the female orgaais. They are first very short, being barely l-2mm. in length. In this condition they show various characteristic struc- tures. The central conducting tissue is seen to consist of slightly elongated cells filled with starch. These cells are destined to play an important part later on in the forma- tion of reproductive cells. In the assimilating layer certain of the cell rows, instead of carrying out their normal func- tion, have developed into procarpia, of which the carpo- gonia form parts. Each procarp consists originally of four cells (fig. 3G). The large basal cell is seen to be con- tinuous with the collecting cells stem inwards. Further outwards it is continued into the two intermediate cells, and finally the one celled carpogonium. This consists of 28 a swollen lower portion, wliicli contains the egg cell and an n])per and sligditly drawn out part called tlie triclio- g-yne, whicli projects beyond the outer limits of the assimi- lating layers into the surrounding Avater. The trichogyne is the receptive organ for the egg cell. The spermatium becomes attached to the trichogyne, but only in a very few algae has tlie fusion of the male nucleus of the sperma- tium with the female nucleus of the egs cell been observed (fig. 36), Shortly before the supposed feitilisation the large basal cell has a small cell cut off called the auxiliary cell. The procarp at this point therefore consists of five cells. After fertilisation the trichogyne is cut off from the fertilised egg cell by a complete closing up of the passage between the two divisions of the carpogonium. The tri- chogyne, now functionless, soon withers away. The fertilised egg cell — the oospore — now grows out, and forms a protuberance m a direction towards the auxiliary cell. This outgrowth is a sporogenous hypha. Its contents fuse with the contents of the auxiliary cell, but as far as has been observed in other cases no fusion of nuclei takes place. The sporogenous hypha has onlv been fed by the auxiliary cell. From the auxiliary cell a number of filaments now grow out. They are, however, only continuations and branches of the sporogenous hypha just mentioned, and represent sporogenous hyphie them- selves. They grow towards the starch-laden collecting cells. These filaments are long-celled and very thin. In their course they form secondary pits with numerous iici"'hbourino- collectino- and conductino- cells. When thev o cy c> o » leach the latter they draw on their large store of food, and finally give rise to the carpospores. The end cells of short branches arising from the sporogenous hyphte, or their last two or three cells give rise each to one carpospore. In 29 the eud the carpophore contains a mass of loose carpo- spores embedded in a mass of exhausted sterile cells. The mass of carpospores forms the cystocarp. The mature carpos})ore is not unlike the mature tetra- spore. It is roundish, and at first unprovided with a definite -wall, which, however, it very soon acquires. Its contents are very dense, a large amount of starchy food being' present. The general colour of the carpospore is red. This is due to the presence of a rhodoplastid, which occurs in a very much divided form. The whole mass of carpospores forms a fairly large cystocarp, which causes a very marked bulging out of the outer assimilating layers of the carpophore. In this way the latter may be distinguished from a frond bearing nemathecia. "What the fate of the carpospores is, we do not know. Presumably they soon germinate, and thus give rise to new plants. Our knowledge concerning the development of the sexual organs of the Rhodophycese is still in a very unsatisfactory condition. The botanist who wishes to obtain any definite results in this connection must, how- ever, live near the sea for a lengthy period, and have a sufficient amount of time at his disposal to carry out extensive and careful continuous observations. E. — Ecology. As a species CJiondrus crispus is found to be fairly widely distributed, being common on the shores of the northern Atlantic Ocean. It forms one of the commonest plants on the seashore in the L.M.B.C. district — in fact, along the whole British coast, as long as the substratum is hard rock and the water is clear, It is a species which 30 grows best in tlie temperate zone. I have no dou'bt that the distribution of the species of marine algte depends on the same factor as that of terrestrial phanerogams. The limits of the distribution of phanerogamic species as a rule coincide roughly with isothermal lines. The distribution of the plant form represented by Chondriis crispus in any given small district is dependent not on the temperature, but on quite different factors. It is impossible to say as yet fully what these factors are. The following account is therefore only short. To begin with, it may be stated that a firm sea bottom is generally necessary for the growth of algse in general. Stones which roll about with every tide never bear red or brown seaweeds, at the most only a few green ones. Sand is always quite barren. Certain algae occur very regularly at certain heights above or below certain hxed levels. I have lately been fixing these heights for a few algae in Port Erin Bay as a jjreliminary to some more detailed investig-ations into the vertical distribution of marine algse. If we call the level of dead low-water mark of an ordinary spring tide 0, then we can divide the shore into a series of regions. AVe will begin from the highest point. Pelvetia canalictdata extends from 12 ' to 17 ' above O. These plants are often left exposed by the sea water for days. The highest individuals are often moistened onlv by the spray of dashing waves. Fucus vesicidosus extends from 3' to 13', but not in the same condition. In an upper region, 9' to 13' above 0, the plants are small, rarely fertile, and possess no vesicles. In the lower region the plants are normal. Ascojdii/IIum ?wdosum extends from 6' to 11' above 0. Fucv.t scrratus forms a very distinct region, 3' to 6' above 0. 31 Laurcitcia piiuiafijhhi begins at about G' above 0, and is closely followed by Laiiiiiiaria difiitata, 5' above 0. Lami- naria saccltaruia begins a few feet lower down. Saccliorldza hidhosa and Alarl'i escttlenta still accompanied by Lami- naria saccJtarina and dlgitata, the latter having about reached its lower limit, are then met with at about 3 below 0. Jlalidrys sdiqnosa is found at a still greater depth. These are the chief plants met with in descending from the highest to the lowest water-maihs. The data mentioned so far refer to plants which lie exposed on the surface of the rock when the tide recedes. It is important to mention this, as many plants rise to a greater height when growing in pools. Laminaria digitata may rise to 9' above 0, and probably higher still in a pool. Exposed, however, its upper limit appears to be 4' lower. The j^lants at the former heights are much smaller than those growing exposed lower down, AVe can say that algae exposed when the tide recedes attain their best development in size and reproductive powers in the lower part of the region to which they belong. As they rise to the upper limits they become smaller. They may, however, be found above their normal limit in pools. The higher pool plants are always smaller than the lower exposed ones. Cliondrus crisjjiis, as a plant lying quite exposed when the tide recedes, extends from -V to 4' above 0 downwards. It has been actually observed to about o' below 0. As a general rule the upper plants are shorter, broader and thinner (PI. L, tigs. 4, 5), than the lower ones. Tbe latter are stouter, very much longer, and the frond is divided into narrower lobes than are found higher up. When growing in pools Cliondrus crispus has been found up to a height 32 of 9' above 0, being often fairly broad, but never very liig'b. It is a plant wliicb is completely exposed only for a short time. Little is known as to the reason why longer and shorter exposure causes a difference in the habit of an alga. AVe practically know nothing about the distribution of and the meaning of the plant forms met with in alg?e. Long submergence in sea water is evidently conducive to increase in size and strength. This is possibly due to the necessity of providing for an increase in assimiUiting power. The forms which are left exposed long become smaller and often rather close set. Plants with bladders are restricted to a limited area, which is probably exposed at every tide, but the significance of the bladders, from an ecological point of view, I have not yet been able to fathom. Tlalidriis siliquostt occurs, with bladders, quite isolated, at great depths. So far it can only be said that marine algee, as a whole, are at their best when least exposed. Certain species, however, by the possession of certain structural or other peculiarities are able to live in localities which must be considered less favourable. They were driven there by the strong competition prevailing in better localities. Pelcet/n CiuiaJicuhda Avas probably unable to stand the competition of the moister parts of the sea shore, and was thereby driven to its present position. Many of the green algie seem to be at their best in the higher regions. A large amount of light seems to be necessary for their well being. Many Chlorophj^ceae seem to be quite indifferent to changes in the salinity of the sea water caused by an inflow of fresh water. The point of greatest interest is still to ascertain that factor, the influence of which the plants have to guard against during exposure. Is it the strong light, or is it 33 the danger of beiug dried up? I do not think tluit tlie latter can be very great. Even witJi a fairly strong wind and strong and warm sunshine, the large individuals of A.-ters. The summary takes the form of a full diagnosis. A diagnosis may include just enough information to distinguish any particular species from nearly allied forms. It is better, however, that it should include more. It should supply as complete but as brief an account of the species as possible, 35 CJtondriis crispus (L.) Stackh. Syxoxymy aisd Literature : Harvey, W. H., Pliycologia Britaunica. 1846-1851. vSyiiopsis 197 (plate 63). A full account of the Syuonyiny will be fouud here. Hauck, ¥., Die Meeresalgen Deutschlaiuls uud Oester- reichs, 1885, p. 134. Illu.stratioxs : Harvey, loc. cit., plate 63 (Syu. 197): general habit of a broad and a narrow form ; transverse and longitu- dinal sections of the stem ; general view and section of nemathecia. Hauck, loc. cit. p. 134, tig. 53 : habit of plant with cystocarpia and nemathecia, with sections of both. Murray, G., Introduction 'to the study of seaweeds. 1895. Plate VI., fig. 3. Wille, N., Entwickelungsgeschichte der physiologischen Gewebesysteme bei einigen Florideen. 1887. ^^ov. Act. Leop.-Garol. Vol. 52, n. 2. Plate VII. fig. 70, 71. Anatomical details. EXSICCATA : Xearly every published collection of dried marine algse contains specimens of this species, so that it is unnecessary to quote here a lengthy list. Remarks. — The Synonymy of Chondrus crisjjus is very straightforward. Harvey refers to certain repro- ductive organs, which he calls " prominent tubercles (nemathecia)," and which are certainly not nemathecia in our sense. Nothing in Chondrus crispus, in fact, corresponds to these prominent tubercles. Murray refers to the spermatia as polliuoids. I see no reason why the term sperma- tium should be replaced by pollinoid, especially as 36 it has notliiiig whatever to do with the pollen grain. The forms and varieties mentioned here and there in the literature are of no special value. Diagnosis : Thallus, consisting of root and shoot. Root, a flat, hard, reddish disc of irregular outline, made wp of very regularly arranged cells of very uniform size and shape. Shoot, upright, 15-17cm. high ; narrow or slightly flattened stalk ; frond repeatedly forked and divided into very much flattened and fhin lobes : internal conducting cells elongated, loose, hyplial in younger parts ; more external and small collecting cells leading into external rows of assimilating cells, each containing one rhodo- plastid. Xemathecia, slightly prominent dark red spots on young lobes ; sporangia in rows ; tetraspores roundish, formed by cruciate division ; mature December to March : in ger- mination the spores divide into a number of cells before increasing in bulk. Spermophores, small, narrow, white leaves on apical marg'ins of frond ; antheridia formed bv two or three outer cells of assimilating layer : spermatangia produce one spermatium each. Mature October to December. Carpophores, small leaflets on frond ; procarpia just inside assimilating layer ; basal cell, cutting off auxiliary cell before fertilisation, two intermediate cells, carpo. gonium and trichogyne ; sporogenous hypha of egg cell fuses with cytoplasm of auxiliary cell, and numerous sporogenous hyphie grow out towards the central starch- laden cells of the carpophore, fusing with them and pro- ducing carpospores ; cystocarps forming prominent dark red patches on the frond ; 'carpospores roundish. Mature December to March. B7 Habitat.— Rocky sea bottom, in clear water, very rarely epiphytic on other alg-se ; low-water mark. Very common in the district. Distribution. — -Atlantic shores of northern hemi- sphere. Economics. — It might be mentioned here — although the point is of no interest botanically — that Chondriis crispus was formerly often used, and — ^I am credibly informed— is still occasionally used, in the making of jellies. It is known as Irish Moss, or carragheen, by chemists, and was supposed to be useful against consumption. In Conclusion, I would like to say that it is most im- portant that the student, who has worked through Chondrus crispus, should examine a number of other red alga?. If staying near the seaside, seaweeds should be collected and carefully examined. Drawings should be made of a few anatomical details and of the reproductive organs. An attempt should be made to name the specimens collected. It may often be impossible for the beg-inner to determine the species, and he must be content if he can ascertain the genus to which it belongs. If he also fails in the latter, the material, together with the drawings, should be laid aside for future reference. Unfortunately we are very badly off at present for any book on the liritish Algse The very good Phycologia Britannica of Harvey was published in 1871, and is there- fore very much out of date. Its illustrations are, hoM-ever, as a rule very good, and the student can use it as a beginning, lint many of the generic and specific names have changed since 1871, and a very large number of new species have been added to our Hora. 88 A BritisL. Marine Flora is being compiled, Init no date for its appearance has, I have been kindly informed, as yet been fixed by its author. The works by Miirra}' and Huuck quoted alcove may be of some help, especially the former, although it treats of foreign as well as liritish marine alga^. It contains a short list of books and atlases of algological interest. Vol. I., part 2, of Eiigler and Prantl's " Die Xatiirlichen Pflanzenfamilien," which treats of the algae, is a very useful book to consult. By the aid of this the beginner may often be able to determine the genera. 89 DESCKIPTIOX OF THE PLATES. Plate I. : The General Habit. Fig. 1. A typical form of low- water mark. Fig. 2. IS^arrow form, low-water mark. Fiff. •). Bi-oad form, low-water mark. Fiff. 4 ami 5. firoad forms, liigk-water mark. All these specimens, drawn natural size, were collected in Port Erin liay, between the Kith and 19th of May, 1901. Plate II.: Axatomy of the Shoot. Fig. (i. Longitudinal section of frond apex, mounted in glycerine JpH}'- x ■>90. Fio-. 7. Longitudinal section of a young' frond a short distance from apex, mounted in glycerine jelly. X 190. Fig. S. Longitudinal section of older part of frond, examined in fresh sea water. x .')90. Plate III. : Anatomy of the Root. Fig. 9. Perpendicular section through the root and the insertion of two upright shoots. The central tissue of the latter is seen to end in the attach- ment organ in a conical form. The root has attached itself to the rock by aneliorlike out- growtlis. X 54. Fig. 10. Perpendicular section through the upper layers of the attachment organ mounted in glycerine jelly. Xotice the regular and unbrauched cell rows, and the series of caps which have been cut off b}^ the tip of each ]'ow towards the surface. X 1075. 40 Fip:. 11. Section in tlie same direction of the reo-nlar cell rows of the inner tissue of the root, mounted in glj'cerine jelly. x 1075. Pi-ate IV^. : Histology of the Shoot. Fig. 12. A central cell from the longitudinal section of an old shoot, stained with hopmatoxylin, mounted in glycerine jf'Hy. Tlu' middle lamella, the darker jwrtion of the cell wall, which lias not swollen up, and the lighter and stratified inner cell wall, which has swollen up, may be distinguished. x 1075. Fig. 1-"). Large pit between two central cells in optical section ; on the left the same in end view. Mounted in glycerine jelly. x about -'iOOO. Fig. 14. The apical (smaller) and next inner cell of an assimilating cell row. The former has a smaller rbodoplastid than the latter. Fresh material. x about 4000. Fig. 15. Transverse section across an inner assimilating cell. The rbodoplastid lines the wall. Fresh material. x about 4000. Fig. 10. The much-divided rbodoplastid of an inner collecting cell. Starch is being formed here and there. Fresh material. x about 4000. I'^ig. 17. Leucoplastid from a conducting cell. Fresh material. x about oOOO. Fig. IS. Starch grain, seen from its broadest (a) and iis narrowest side (b). Examined in iodine and glycerine. x about 3000. Pl.\te v.: The Xemathecifm. Fig. 19. Habit of a plant bearing nemathecia. x 2. Fio\ 20. Louffitudinal section of a froud contaiuinir a uematliecium. x 4"i. Fig. 21. Section showing- tlie undivided spore mother- cells lying in rows, which are continued into the assimilating filaments. Fresh material. xlOTo. Fig. 22. Mass of divided tetrasporangia, surrounded l)y the sterile cells in a nemathecium. Fresh material. x 1075. Fig. 23. Form of cruciate division of a sporangium. Diagrammatic. Fig. 2-1. Another form of the same. Diagrammatic. Fig. 25. Another form of the same. Diagrammatic. Fig. 20. Single free tetraspore. It is filled with food material ; the darker portions represent parts of the much divided rhodopUistid. x about 3000. Plate VI.: The NEMAXHECirM and the Speemophoee. Fig. 27. Free tetraspore, some time after its escape, and surrounded by a wall. In glycerine jelly xl075. Fig. 28. A tetraspore, having germinated to four cells. In glycerine jelly. x 1075. Fig. 29. Germinal product of a tetraspore forming a rhizoid-iike outgrowth. In glycerine jelly. xl075. Fig. '60. Frond bearing spermophore at its tips. x 2. Fig. '61. Two spermophores. x 12. Fig. '6'2. Outer layers of the tissue of a spermophore. The assimilating cell rows end in antheridia. The last cell of each antheridium, the sperma-. tangium, gives rise to one spermatium. In glycerine jelly. x 1075. 42 Plate VIT. : The Car[>ofhore. Fig. •■)•'). Frond bearing several cystoearps. x 2. Fig'. •)4. Longitudinal section of a carpophore, showing the spore mass of the cystocarp bulging out. x43 Fig. -lb. (jrroup of carpospores surrounded by numerous sterile cells. The two lowest are showu with dark spots, which represent portions of the tinoly divided rhodoplastid. x 1075. Fig. -Xi. Diagrammatic view of the procarp. The single arrow line shows the sporogenous hypha grow- ino- out from the fertilised eg-g" cell. The three arrow lines indicate the course adopted by the several sporogenous hy})hce growing out from the auxiliary cell towards the nourishing cells of the centre of the carpophore. C. Tinliiig ami Co., Printers, .53, Victoria Street, Liverpool. L.M.B C. Memoir IX. Plate I. OVDdel s.B.m CHONDEUS. General Habit. L.M.B.C. Memoir IX. Pl/vte n. OMD.dd CHONDPJJS. Anatomy of the Shoot SBiith. L.M.B.C. Memoir IX. Plate III, Fig 10. Ficfll. ii£y i"^*! J^"^^ ';^^Sf ^ '^^ C^^ i5~ ^^^' rz:^^ ^\ ifl ^ ^^^ ^-^^