ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 319 



which there are a very large number of pyrenoids. The chlorophyll is 

 probably diffuse throughout the cytoplasm. The cells of the brauching 

 thallus appear to have no contents. 



Fresh-water Algae of New South Wales.* — G. I. Playfair publishes 

 •a. census of New South Wales fresh-water algse, as a supplement to Maiden 

 and Betche's " A Census of New South Wales Plants" (1916). He 

 follows the classification used in G. S. West's " British Freshwater Algae " 

 (1904), and in his introduction summarizes the differences between 

 this classification and that in Engler's " Syllabus der Pflanzenfamilien " 

 (1904). The latter system is inadequate and incomplete. Playf air's 

 census contains six genera of Phaeophycea^, forty-eight of Chlorophyceai, 

 twenty-three of Desmidiacea3, four of Heterokontte, thirty-nine of 

 Bacillariege, twenty-one of Myxophycea^. And, adding all the species, 

 varieties, and forms together, we find a total of 1061. Further, there 

 are three genera of Phycomycetes aud six of Schizomycetes, with a com- 

 bined total of twenty-eight species, varieties, and forms. And most of 

 them the author has collected and identified personally. 



Algal Ancestry of the Higher Plants.f — F. E. Fritsch, in dis- 

 cussing the Algal ancestry of the higher plants, gives the following 

 ■summary : — 1. In all the more advanced groups of the algge, the thallus 

 ■exhibits frequent differentiation into a creeping base and an upright 

 system. 2. Among the Chgetophorales, which plainly show such a 

 differentiation of the thallus, there are evidences of unlimited poten- 

 tialities ; we also find in this group — (a) a whole series of terrestrial 

 forms ; (b) the only member of the Isokont^e with a distinct main axis 

 bearing laterals which carry on assimilation and reproduction ; and (c) in 

 the species of TreniepohUa, forms showing relegation of the sexual 

 organs to the base, and of asexual organs to the upright system. 3. The 

 .available evidence is regarded as pointing to the Isokontse for the 

 ancestry of the higher plants, and, for the reasons mentioned under 

 paragraph 2, this ancestry is thought to lie among forms resembling the 

 ■Chietophoraies. 4. The Pteridophyta are supposed to have arisen from 

 «uch forms by the gradual divergence of two generations, the sexual 

 ■derived from the creeping base, the asexual from the upright system. 

 The Bryophyta are supposed to have arisen from forms resembling 

 ■Coleochdete by gradual elaboration of the zygote. 5. Cutleria, in a side- 

 line of evolution, fully illustrates the way in which two generations can 

 l)e derived from the type of thallus common in all the main groups of 

 the algge, after the manner postulated for the case of the Pteridophyta. 

 6. The cases of alternation among the algfe may be distinguished as 

 follows : — (a) The two generations arise from different parts of the 

 ancestral sporo- and gameto-genetic thallus {pseudo-homologous alterna- 

 tion) : (1) The gametophyte is prostrate, the sporophyte erect (Pterido- 

 phyta, possible cases to be found among the Ohastophorales) ; (2) the 



* Census of N.S. Wales Plants. Supplement I. Fresh--water Algse. Sydney: 

 GuUick, 1917, pp. 217-63. 



t New Phytologist, xv. (1916) pp. 233-50 (fig».). 



