336 BOOKS AND CURKENT LITERATURE , 



Heterokontae, with three orders (Heterococcales, Heterotrichales, 

 Heterosiphonales). The order Microsporales of the older work is now 

 made a famil}' of the Ulotrichales. 



It seems to the reviewer that the Heterokontae should have been 

 retamed as a separate class from the Chlorophyceae, since the differences 

 between the two are thoroughgoing and far-reaching, and since the 

 points of origin in the Flagellatae are considered for good reason to be 

 different in the two groups. However, the subdivision of the Hetero- 

 kontae is m.uch more natural than in the older work, where only one 

 order, the Confervales, was recognized. In this were lumped the most 

 diverse famihes. The present satisfactory subdivision into three 

 orders is modified from Pascher. 



In general the classification adopted by the author is along the lines 

 suggested by Bohlin and by Blackman and Tansley, differing in impor- 

 tant points from the schemes of Oltmanns, Chodat, and Wille. 



The material under the heading " Chlorophyceae" is so scattered in 

 the different subdivisions that it is hardly possible to give a comprehen- 

 sive review of it. Certain points may be commented upon. The 

 statement (p. 138) that "no positive evidence of the reduction of chromo- 

 somes" has been brought forward in the case of Spirogyra is, of coiuse, 

 misleading, since Trondle's paper in the Zeitschrift fiir Botanik, 1911, 

 settles this question. 



In the discussion of alternation of generations (p. 139) the chromo- 

 some number is accepted as the only factor in delimiting sporoph>i,e 

 and gametophyte. Thus the author says, granting the correctness of 

 Allen's conclusions in Coleochaete, "It is scarcely possible to regard these 

 post-natal phenomena [of the germination of the zygospore] as phyloge- 

 netic fore-runners of the sporophyte of the Archegoniates." No golden 

 calf of old was ever worshipped with the fervor that many botanists of 

 today exhibit for the chromosome. As an example of the lengths to 

 which it may go the recent paper of Cunningham on Spirogyra may be 

 cited (Bot. Gaz. 63, p. 498), in which this remarkable conclusion may 

 be found: "The filam.ent of Spirogyra, in this species and those with 

 lateral conjugation, is homologous with the sporophyte of higher 

 plants." Here not even the substance, but the mere shadow of the 

 chromosome frightens common sense and the reasoned conclusions of 

 comparative morphology off the page. So with our author's treatment 

 of the subject. 



There follows a good discussion of polymorphism. Methods of cul- 

 ture given in this connection will be found useful (pp. 143-144). The 



