[Vol. 2 



316 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



In this abstract the statements must be more or less cate- 

 gorical, and some will therefore appear rather dogmatic. 



1. The phylogenetic relation of the ooblast ema filaments of 

 the red algae, and the ascogenous threads of the sac fungi. — 

 The nuclear history in the two structures is very different. In 

 the red algae there is a single fusion of one pair of sex nuclei 

 in the egg, forming a true diploid nucleus which multiplies by 

 division in the ooblastema filament providing the primary 

 nucleus for each cystocarp. The ooblastema filament fuses 

 with vegetative auxiliary cells to furnish attachment and base 

 for food supply of the cystocarp, but the diploid and haploid 

 nuclei of the fusion cell repel each other. The attempt to 

 show a phyletic relation between the copulation of short 

 ooblastema filaments with cells of the procarp, or the fusion 

 of the procarp cells, after the union of haploid gametic nuclei, 

 in some groups of red algae, and the communication of func- 

 tional archicarp cells of certain sac fungi, as well as entertain- 

 ing the notion that fusions of approximate cells of the asco- 

 genous hyphae are phyletically related to the fusion of ooblas- 

 tema filaments and auxiliary vegetative cells, introduces 

 additional confusion into a doctrine already overburdened 

 with questionable hypotheses. The ooblastema filaments and 

 ascogenous threads are parallel developments. They present 

 an example of morphological homology or analogy, not of 

 phylogenetic affinity. 



2. The phylogenetic relation of the ascus and carpospore, 

 or tetrasporangium (see Part n, Notes n and m). — There are 

 two horns to the dilemma here, and either one requires several 

 additional supporting hypotheses. The origin of the ascus 

 from a coenocytic zygote, in some cases by reduction, in others 

 terminating a progressive splitting of the same, is far more 

 comprehensible. The nuclear fusion in the ascus is not vege- 

 tative (see Note in). It takes place in all forms thus far in- 

 vestigated and is to be considered the final stage of the sexual 

 act, however modified this may be. Were it merely vegetative 

 fusion there would be no need of conjugate division in the 

 ascus hook to avoid the union of sister nuclei. The nucleo- 

 cytoplasmic relation, or balance, would be just as easily at- 





