No. 325] 



svxr.iL uEPiianrcTKtx i.x ai.c.k 



based the suggestions of an alternation of generations in 

 the Cutleriaceae. 



A preliminary paper l>y Yamanouchi 12 on the above 

 named species presents cytologies] evidence in support 

 of the theory that they are sexual and asexual phases, re- 

 spectively, of the same life history, with the relation one 

 to the other of gametophyte and sporophyte. The vege- 

 tative mitoses of Cutleria multifida and those leading to 

 the formation of the male and female gametes show uni- 

 formly twenty-four chromosomes. The zygote develops 

 at once into a sporeling, the nuclei of which have forty- 

 eight chromosomes. There is thus no reduction of the 



and the sporeling which results must be considered as 

 sporophytie in character. 



The vegetative mitoses of Aglaozonia reptans exhibits 

 forty-eight chromosomes, but the nuclear divisions within 

 the sporangia are quite different. Following the differ- 



stage of synapsis in which the chromatic spirem is ar- 

 ranged in a series of loops from which are developed 

 twenty-four bivalent chromosomes. The first division in 



mitoses in this cell exhibit the reduced number of chro- 



panied by reduction phenomena, there must be in its life 

 history a sexual phase of which it is the sporophyte gen- 

 eration, and the number of chromosomes as well as other 

 details of cell structure present strong cytologieal evi- 

 dence that the gametophyte is Cutleria. Such evidence 

 supporting the conclusions of the earlier writers based 

 on the seasonal habits of Cutleria multifida and Aglao- 

 zonia reptans and on the structure of the respective 



generations in the ( 'utleriaoea* as is possible short of the 

 actual cultivation of these alga- from zygotes and zoo- 

 spores to fruiting maturity. 



