﻿330 BOTANICAL GAZETTE [may 



gamete (carpogenic cell). These conditions are nowhere pre- 

 sented in the red algae, and it is very difficult to understand 

 how a uninucleate gamete could develop such elaborate struc- 

 tures. But taking the suggestion of Harper (1900) that the 

 conjugating tube of Pyronema is an outgrowth similar to a 

 trichogyne, there are presented possibilities of various elaborate 

 structural developments, because the outgrowth has so much 

 protoplasm and many nuclei to draw upon. The evolutionary 

 tendency of a coenogamete is to reduce the number of func- 

 tional gamete nuclei, generally by the sacrifice of many, but 

 these with accompanying cytoplasm are sometimes employed to 

 advantage in developing structural adaptations. Ir\ the Peron- 

 osporales the advantage lies in the activities displayed by the 

 periplasm in assisting to form the spore wall. Araiospora 

 (Thaxter, t8q6) utilizes the periplasm to develop a cellular 

 envelope surrounding the ^^"g. The conjugating tube of Pyro- 

 nema is evidently a desirable specialization, insuring a union 

 with the male organ. Perhaps the elaborate multicellular tricho- 

 gyne is the result of similar activities on the part of archicarps 

 that are or were coenogametes. 



It is obvious that this possibility has very important relations 

 to comparisons that have been made between the trichogynes of 

 the Ascomycetes and those of the Rhodophyceae. It is not 

 easy to homologize these structures, and it is difficult to conceive 

 the evolution of any group of the Ascomycetes from the red 

 algae. The Laboulbeniaceae exhibit certain strong resem- 

 blances in a general similarity of cell structure, but peculiarities 

 confront one whenever the comparison is carried into details. 

 Nevertheless a relation of this group to the Rhodophyceae 

 remains a possibility, although it can hardly be more than mere 

 speculation until we have much greater cytological knowledge 

 of sexual processes here and in other Ascomycetes. 



But the coenogamete may be found widespread among the 

 Ascomycetes, which suggests a new point of view that is worth 

 attention. It is possible that the coenogamete may come to be 

 recognized as a primitive type of sexual organ in the Ascomy- 

 cetes, as the writer believes it to be for certain groups of the 



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