RECENT LITERATURE ON FRESHWATER ALG.H. - 197 



above the surface of the sea, the presence of C. Lejirieurii at no 

 great distance from the Malay Archipelago points rather signifi- 

 cantly to the ancestor of D. amboinensis. 



Prof. Goebel remarks that the occurrence of tetraspores iu 

 D. zamihariensis is the only known instance among freshwater 

 Floridea. In the British Museum, however, there are tetraspores 

 on the specimen of C. Leprieiini from the mountain stream of 

 Ponce, Mauritius, mentioned above. If, therefore, D. zanzibariensis 

 and C. Leprieurii were to be regarded as distinct species, this 

 statement could not pass unchallenged ; and if the two plants are 

 allowed to be identical, there still remains Bostnjchia [Dasija) 

 Lauterbachi to be considered, the stichidia of which are described 

 and figured by the authors in their original diagnosis of the 

 plant (/. c). 



The same part of Flora (Jan. 1898) contains a paper by Dr. 

 Oltmanns on the " Development of the Reproductive Organs in 

 Coleoch(Ete piilvmata.'' He makes some additions to the results 

 published by Dr. Pringsheim (Beitr. z. Morph. u. System, d. Algen, 

 iii. Pringsh. Jahrb. Bd. ii. 1860), but comes to the conclusion that 

 on the whole ColeochcEte is a "quite ordinary" (ganz gewohnliche) 

 plant, and unworthy of holding the important position of con- 

 necting-link between any great groups in the plant world. He 

 adds that Niigeli had, however, come by another road to the same 

 conclusion. It is disappointing to find no observations on the 

 number of the chromosomes in the two generations, a point on 

 which botanists have been waiting for some time for information. 



A paper entitled '' Observations on the CoujugatcB,'' by Messrs. 

 W. and G. S. West, is published in the Annals of Botany for 

 March, 1898. The authors embody in this paper the results of 

 their investigations, "founded on a prolonged study of freshwater 

 algae from^ all parts of the world." They divide the ConjugatcB into 

 three families — Zygnemace(B, which includes MesocarpacecB, Temno- 

 gametacecB, and Desmidiacece, and each family and subfamily is 

 treated of in turn. Interesting facts are given with regard to the 

 extremes of heat and cold at which these alga3 can live, and speci- 

 mens of Closteiiimi Leihleinii are quoted, which were in "perfectly 

 healthy and normally active condition" after having been frozen 

 in the ice at Frizinghall, West Yorkshire, for over fourteen days. 

 This instance is not exceptional, for the authors record species of 

 Spirogi/ra, Moiigeotia, &c., which have survived in temperatures 

 below freezing-point. These conclusions are the more interesting, 

 as being contrary to those published by Mr. Ewart " On Assimila- 

 tory Inhibition in Plants" (Journ. Linn. Soc. vol. xxxi. 1896, 

 p. 395), where he says, speaking of freshwater alg^, " These plants 

 are not very resistant to cold, all those examined being killed by 

 being frozen." 



It is also shown that direct sunlight "under natural con- 

 ditions " is not only fatal, but tends to the formation of zygospores 

 in Conjugat(B, though, as Mr. Ewart shows {I.e. pp. 439, 440), 

 experiments under artificial conditions give a different result. 



In conclusion the Messrs. West give a phylogenetic table of the 



