Fresh-Water Algce of Canada. 465 



Hass., Brit. F. W. Alg., p. 213, pis. 56 and 57, figs. 1 and 2 ; 



Harv. in Manual, p. 134. 

 Hah. — Common over the whole length of the fresh-water por- 

 tion of the St. Lawrence, the Ottawa, and their tributaries. 

 The characters by which to distinguish the species of this arti- 

 culate genus of Algae are very slight, and require great caution in 

 'he observer so as not to multiply species without cause. A great 

 difference in the diameter of threads belonging to the same frond 

 will constantly be found, and the proportions of length and breadth 

 in the articulations are quite variable. Berkeley says, in his 

 "Introduction to Cryptogamic Botanj T ,'' P> 166, that "specie?, 

 evidently of the most close affinity, cannot be separated from mere 

 consideration of relative proportion without any other characters. 

 Even the branching of the threads is not sufficient, or the mode 

 of branching. Cladophora glomerata assumes a multitude of 

 forms which it would be rash in the extreme to separate; and it 

 may safely be affirmed that of published species of Cladophora 

 and Conferva, at least one-half will ultimately be reduced." 

 There is a normal character in the forms of the cells and in the 

 style of branching which the practised eye soon detects. But, so 

 variable are the appearances of Cladophora, and so modified are 

 its characters by habitat, that it is hard to divide them into species 

 at all. Hassall, not over scrupulous as to the multiplication of 

 species, -himself admits only two into his distribution of the genus. 

 Under C. glomerata he includes C. aigagropila (Linn.) and C. 

 Brownii (Harv.), and accounts for the appearance of the former 

 by the force of the mountain streams rolling detached portions of 

 C. glomerata into compact balls ; and of the latter by the sub- 

 immersed habitat in which it grows. It is also with doubt that 

 he admits his second species, L. crispata, to a distinct place. 

 The three British species, C. nigricans, C. fracta, and C.flaves- 

 cens, he refers to this one ; all being, as he thinks, different states 

 of the same plant. He concludes by saying that " The suspicion 

 also may, I think, be entertained that C. crispata itself is but a 

 condition of C. glomerata, changed by the difference in its place 

 of growth — it growing for the most part in still water, in deep 

 ponds, and lakes. I have often seen specimens which it would be 

 impossible to refer with certainty to either species." 



The fructification- of this plant is very simple. Every cell 

 seems to contain fertile zoospores. At maturity they either burst 

 through the cell walls, or a natural apperture is formed for their 



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