1915] 



ATKINSON PHYLOGENY IN THE ASCOMYCETES 333 



case has fertilization by a free sperm been determined, and in 

 forms with a multiseptate ' * trichogyne, ' ' or oogonium, the so- 

 called spermatia, or antheridia, do not, so far as we know, play 

 the usual role in fertilization, not even a modified role by asso- 

 ciation with the oogonial nuclei. 



2. The individual nuclei of the ooblastema filaments are of 

 the usual diploid character, and there is no fusion of these 

 nuclei prior to the formation of the carpospores. The indi- 

 vidual nuclei of the ascogenous threads, or ascogenic cells, are 

 probably haploid in character, and sooner or later form the 

 so-called synkarion, an association of two nuclei, together 

 equivalent to a diploid nucleus. Fusion of the paired nuclei 

 takes place before the formation of the ascospores. 



3. It has been suggested that the complex processes in the 

 extensive migration, branching and fusions of the ooblastema 

 filaments with auxiliary cells as is known to occur in the 

 Cryptonemiales (as in Dudresnaya, Cruoriopsis, Gloeosi- 

 phonia, etc.), may furnish still more important evidence of 

 the ancestry of the Ascomycetes than that suggested in the 

 fusions of procarp and auxiliary cells on the one hand, and 

 archicarp cells on the other (Dodge, '14). The fusions of the 

 ooblastema filaments with auxiliary cells and the production 

 of sporogenous threads from the central cells thus formed, 

 are supposed to be represented by the fusions which are known 

 to occur between the ultimate and antepenult cells of the ascus 

 hook prior to the formation of additional asci. The processes 

 in both groups result in the multiplication of spore origins 

 and consequently in an increase in spore output. Perhaps the 

 nearest analogue to the process in the Ascomycetes which re- 

 sults in the formation of the ascus with its four to eight spores, 

 is found in Cruoriopsis, where one or two spore chains of two 

 to four spores each are produced as a result ( Schmitz, 79, '83 ; 

 Oltmanns, '04). The theory of ''second sexual fusions" in 

 the red algae was founded on the discovery of these fusions of 

 the ooblastema filaments with auxiliary cells, since it was sup- 

 posed that a fusion occurred between the nucleus of the 

 ooblastema filament (derived from the diploid nucleus of the 

 fertilized Qgg) and the nucleus of the vegetative auxiliary cell 



