4. Fortpflanzungslehre. 79 



Wager brought forward the first evidence of endokaryogamy, or the 

 fusioii of closely related nuclei, in the basidium. The binucleated condition 

 of the cells extends back into the mycelium, and may perhaps come about as 

 early as the germination of the spore itself. In the rusts, the uredo mycelium 

 remains binucleate, although fusion of the nuclei finally occure in the telento- 

 spore. This binucleate mycelium is therefore the sporophytic phase, and is 

 dominant and progressive in the life cycle, just as in higher plants. Two 

 nuclear fusions are found to occur in the smuts as in Ascomycetes. 



The two divisions involved in the formation of the promycelial cells is 

 considered to be the reduction period, and the binucleate condition is every- 

 where regarded as equivalent to a sporophyte. The triple division in the ascus 

 is comparable in universality and importance, with the double division in 

 spore mother cells. Among the cytological peculiarities of the fungi may be 

 mentioned: 



1. The fusion of multinucleate gametes. 



2. Endokaryogamy, the fusion of nuclei not brought together by cell 

 fusion but of more or less independent ancestry. 



3. The fusion of gametes without the fusion of their nuclei. The latter 

 may finally fuse just before the reduction division after a long series of con- 

 jugate divisions. 



4. Fertilization by nuclear migration from a vegetative cell to an egg 

 or fertile cell. 



5. Two successive fusions in the game life cycle, a normal conjugation of 

 gametes and later endokaryogamy. The tendency is for the latter to acquire 

 a sexual significance, and for the paired condition of the nuclei to „work 

 back" from the spore mother cell into the tissues of the sporophyte. 



Gates (St. Louis). 

 207) DaTis, B. IL, Nuclear phenomena of sexual reproduction in 



(Amer. Nat. 44,525. p. 513-532. 1910.) 



The writer considers the recent cytological investigations of the Algae, 

 in their bearing on our knowledge of the life cycles and phylogenies in the 

 various groups. The paper indicates a strong belief in the view that the 

 Processus of fertilization and chromosome reduction represent the points 

 of alternation between antithetic sporophyte and gametophyte generations. 



It is pointed out that in the Chlorophyceae reduction probably takes 

 place immediately upon the germination of the zygospore or oospore as sbown 

 by the studies on Spirogyra, Coleochaete, Closterium and Cosmarium. In the 

 Phaeophyceae, the studies of Williams, Farmer, Strasburger, Yama- 

 nouchi and others, have shown how complex and varied are the conditions 

 of alternation of generations in the three groups, Dictyotales, Fucales and 

 Cutleriaceae. An understanding of the life cycle in the Rhodophyceae, has 

 come chiefly through the investigations of Wolfe on Nemalion, Yama- 

 nouchi on Polysiphonia, and Lewis on Griffithsia. Wolfe considered 

 the cystocarpe of Nemalion to be sporophytic, and believed that reduction 

 took place just previous to the development of the carpospore. It is possible, 

 however, that reduction is delayed until the germination of the carpospore. 

 In Polysiphonia Yamanouchi showed that reduction takes place in the for- 

 mation of the tetraspores, and that the tetrasporic plants are therefore sporo- 

 phytic while sexual plants are gametophytic. Lewis found a similar alter- 

 nation of tetrasporic and sexual plants in Griffithsia. 



It is suggested that the occasional presence of structures resembling 

 tetraspores on sexual plants in various Red Algae, and the fact that in Rhody- 



