[Vol. 2 



326 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



posites, the highest stage of phyletic evolution in the plant 

 world. 



In conclusion, the Ascomycetes present a very rich variety 

 of form, structure, and adaptation with very marked diverging 

 series. Some of these series present evidences of progres- 

 sion from simple, generalized forms to highly specialized 

 forms, while others indicate descent by reduction. The evi- 

 dences of progression are of the same kind and value as are 

 generally recognized in other groups of plants. 



Sachs, in his later writings, 

 agreed with deBary in recog- 

 nizing the Ascomycetes as a 

 distinct phylum, with an as- 

 cending series from simple 

 and generalized forms to com- 

 plex and specialized ones. He 

 never mentioned the tricho- 

 gyne as evidence of their phy- 

 letic relation to the red algae. 

 But his theory was based on 

 the presence of a procarp whether with or without a tricho- 

 gyne. He selected Gymnoascus, where the sexual apparatus 

 consists of simple copulating gametangia, as the simplest 

 ascomycete known at that time. It is only in recent years 

 that the trichogyne has been seized upon as evidence of the 

 phyletic relation of the two groups and has forced this 

 anomalous backward reading of the history. 



Fig. 4. Gymnoascus Reessii: A-D, 

 formation of sexual organs, fusing at C; 

 E, sexual organs in uninucleate condi- 

 tion; F, fusing sexual organs in multi- 

 nucleate stage. — After Dale. 



Part II. Elucidation 



NOTE I 



The red algae are remarkable for the great constancy in the 

 form of the procarp (procarpic branch, carpogonial branch, 

 etc.) and the very great divergence in the processes subse- 

 quent to the fertilization of the egg (terminal cell of the pro- 

 carp, carpogonium) and ending in the production of the carpo- 

 spores. The general character of this divergence may be 

 shown by a brief presentation of several types, as follows : 



