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SCIEMCE-G0331P. 



two." And again, " The whole of these changes 

 are so palpable, can be observed so constantly, and 

 are at the same time so simple in their relations to 

 one another, that one can scarcely imagine how 

 they can have been separated not only into distinct 

 species, but into different families of algse. Thus 

 the linear stage is called Lynabya, the early stage 

 of collateral segmentation Schizognnium, the adult 

 stage Prasiola, while the gonidial growth has been 

 classed under Palmellacese." 



There is nothing in the above quotation but 

 what certainly may easily be the fact. The cells 

 composing the various forms do not differ from 

 each other more than the cells from different 

 specimens of any one of them. It is important also 

 to remember that all the cells from a physiological 

 point of view are of exactly the same value, they 

 must all of them perform the functions of an 

 entire plant, there is here no modification of 

 structure in order to fulfil different duties, such as 

 is apparent in the higher plants. Each com- 

 ponent item is at once functionally root, and stem, 

 and leaf, and even reproductive body too, so that 

 the mere external form of the whole colony may 

 well be but a secondary matter and dependent on 

 age, or the diverse conditions of environment. Of 

 course it is not contended that all species of 

 Ulothrix, as now understood, are but the immature 

 condition of another plant, but the one only, and 

 its somewhat uncertain varieties which would 

 formerly have been known as Lynghya muralis. 

 Still, the assertion does not appear to have been 

 generally accepted as final, and though often 

 quoted with approval, the old classification is yet 

 adhered to. Indeed, the truth of the matter is not 

 so easy to ascertain as might be expected. Nothing 

 would appear to be more simple than to obtain 

 specimens of Lyngbya, keep them under observation 

 during growth (they flourish readily with reason- 

 able treatment), and in due course they should 

 develop through Schizogojiinm into Prasiola. Yet 

 almost certainly it would be found they did 

 nothing of the kind, but continued as Lyngbya still. 

 To quote Dr. Hicks again: "There seems an 

 innate tendency of any one form to continue and 

 to multiply in that form in all stages of this plant, 

 whether in the free segmenting gonidial stage, in 

 the early half-grown or mature linear, or, later on, 

 in any stage of the collateral mode. This property 

 is possessed by most if not all the lower algae, and 

 it is this which has doubtless tended to divide into 

 distinct species and genera forms which should 

 have been but the links of a single chain." 



Interesting as it might be, it is needless here to 

 enter on a discussion as to the merits of Dr. Hicks' 

 theory. I have watched the plants for several 

 years and have grown specimens at home at inter- 

 vals during the time, but find the whole of them 

 vary so much according to season and habitat, 

 while the descriptions in most books are so 

 indefinite (it is mainly after all a question of 

 definition) and even contradictory, that it would be 



useless to offer a decided opinion on the mattef. 

 The remark may be permitted, however, that to 

 me it seems impossible to establish the genus 

 SchizogonUim. All the many specimens that have 

 come under my observation appear to represent 

 either a state of Lytigbya in which the filaments 

 have become connate, or a young condition of 

 Prasiola developed from some of the proliferations 

 to which it gives rise. Lyngbya is much more 

 common than either Schizogoniwn or Prasiola, 

 it may almost be described as ubiquitous so 

 plentiful is it, and though in the vast majority of 

 cases it retains its own proper characteristics, and 

 does not develop into anything else, a form does 

 occasionally occur, and just recently I have found 

 it in great abundance in one situation, which 

 somewhat resembles the other two. Probably in 

 consequence of the wet and mild winter, added to 

 some special suitability in the site, a patch of it 

 has grown with great vigour and luxuriance, the 

 filaments being crowded together, have adhered to 

 one another and united into ribbon-like structures 

 of varying widths, according to the number of 

 threads taking part in the process. Not in- 

 frequently this has gone so far that the result 

 is a broad membranous frond. Now the 

 narrower examples agree precisely with part or 

 the definition already given for Schizogonium : 

 "Threads as in Ulothrix; or, in many places, 

 laterally connate (i) (duplicate or triplicate)"; 

 while the broader ones, consisting of expanded 

 fronds, are in general appearance like Prasiola. 

 Indeed, this seems to be the form described under 

 that name in the third edition " Micrographic 

 Dictionary." Well marked as these structures 

 are, they certainly do not require a specific name, 

 their origin is evident, the actual filaments are 

 quite distinguishable lying side by side, marked 

 out, but at the same time connected by the 

 thickened walls which appear like broad, almost 

 colourless, stripes. In the wider specimens, owing 

 to the junction of threads lying in different 

 directions in one plane, angular spaces often 

 occur between them, leaving openings ; and the 

 shape of the whole frond, particularly the edges, is 

 most irregular. 



Besides the interest attaching to their develop- 

 ment, and their beauty as microscopic objects, 

 these plants have the further attraction of bearing 

 preparation and permanent mounting extremely 

 well. Indeed, with very little trouble they may be 

 preserved so as to retain their natural appearance 

 even to the colour, for years, so that typical 

 specimens and their variations can be laid by for 

 future reference. In the last October number of 

 Science- Gossip we had a receipt given for a 

 mounting fluid which would no doubt be highly 



0) Connate — " having parts united in any stage of 

 development, which are normally distinct," 



