[VOL. 2 



324 ANNALS OP THE MISSOURI BOTANICAL GARDEN 



that where the sperm nuclei of the simple antheridium are 

 functional. 



Notwithstanding this interesting course of evolution of the 

 antheridium and of sexuality which we trace if the red algae 

 are accepted as the source of the Ascomycetes, I believe, just 

 as in the case of the archicarp and trichogyne, the evidence 

 warrants us rather in reading it in just the opposite direction ; 

 and that in the last stages of progressive development of the 

 sexual apparatus in the Ascomycetes, the resemblances to the 

 sexual apparatus of the red algae are merely those of mor- 

 phological homology and analogy, not phylogenetic homology 

 and affinity. 



According to this view, then, the ancestral forms of the 

 Ascomycetes were fungi with well developed, simple but gen- 

 eralized gametangia. This condition is retained in a number 

 of existing Ascomycetes, in many of which true sexuality 

 exists.^ 



In connection with the specialization of the antheridium and 

 the origin of the spermatia of the Ascomycetes, Monascus is 

 an extremely interesting form. The antheridium is an 

 elongate terminal cell of a hypha. The archicarp arises as a 

 branch below the septum. It curves closely against the an- 

 theridium, bending it over more or less at right angles, and 

 copulates at any point along the side of the antheridium, there 

 being no portion of the latter especially selected as a copula- 

 tion place. The conidia in Monascus are formed in chains by 

 constriction and septation of terminal portions of hyphae 

 similar in diameter to the antheridium. The archicarp some- 

 times copulates with a conidium of the chain before their final 

 separation (Barker, '03). A chain of conidia is thus homol- 

 ogous with the antheridium, and a conidium with any section 

 of the antheridium. It would be but a step from this condi- 



* Examples of generalized, simple (non-septate) gametangia are found in 

 Dipodascus and Gymnoascus. Examples of simple specialized gametangia, i. e., 

 uninucleate gametangia, are found in the powdery mildews (Erysiphaceae) and 

 Eremascus. A second stage is presented in forms where the antheridium remains 

 simple and generalized, but there is a beginning of specialization in the archicarp 

 where it is split transversely into two cells, the terminal one (trichogyne) func- 

 tioning as a copulating organ and migration tube for the sperm nuclei. Examples 

 are found in Pyroncma and Monascus. 



