[Vol. 2 



332 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



dependency in different groups of the fungi as a means of 

 permitting the association of nuclei, often in conjunction with 

 the association of sex nuclei or their equivalent modified sex 

 nuclei (see the situation in Basidiobolus, Eidam, '86; Raci- 

 borski, '96; Fairchild, '97; Olive, '07; Woycicki, '04). 



Relation of ooblastema filaments and ascogenous hyphae. — 

 In the Ascomycetes the processes in the growth of the zygote 

 or ascogenic cell present to a certain extent a somewhat analo- 

 gous course of progression to that of the carpogenic cell of the 

 red algae. In the less complicated process, as shown in the 

 Laboulbeniales, the carpogenic cell may undergo a few divi- 

 sions, the subterminal cell of the series forming the as- 

 cogonium. The ascogonium then usually divides to form two 

 or four ascogenic cells, or without division forms the single 

 ascogenic cell (Thaxter, '96; Faull, '12). The ascogenic cells 

 give rise directly, by budding, to the asci. They are, there- 

 fore, somewhat comparable or analogous to the gonimoblasts 

 of the red algae. In Sphaerotheca (Harper, '95 a , p. 475) 

 there is a single short ascogenous thread of a few cells (arising 

 from the one-celled oogonium or ascogonium) forming a single 

 ascus from the subterminal cell. Where the process is more 

 complex, as mPyronema (Harper, '00; Claussen, '12), several 

 long ascogenous hyphae arise from the large single-celled 

 zygote or ascogonium, giving rise ultimately to numerous 

 terminal asci. In other forms the ascogonium is several- 

 celled, a number of the cells developing ascogenous hyphae 

 (Collema, Stahl, '77; Baur, '98; Bachmann, '12, '13; Anap- 

 tychia ciliaris, Baur, '04; Physcia pulverulenta, Darbishire, 

 '00; Ascophanus carneus, Cutting, '09; Lachnea cretea, 

 Fraser, '13; etc.). 



Some of the chief objections in the way of accepting the 

 theory of a phylogenetic relation between the ooblastema fila- 

 ments of the red algae and the ascogenous threads of the sac 

 fungi are as follows : 



1. The fusion of a free sperm and the egg nucleus in the 

 single uninucleate oogonium or carpogenic cell. So far as we 

 know this is universal in the red algae. In the Ascomycetes 

 the oogonium is usually multinucleate or multiseptate. In no 



