178 REPRODUCTION 



In Coleochaete, a genus of small fresh-water green algae, a trichogyne is 

 also present in some of the species: it is again a prolongation of an oogonial 

 cell. 



In the Ascomycetes, certain cells or cell- processes associated with the 

 ascogonium have been described as trichogynes or receptive cells. In one 

 of the simpler types, Monascus^ the " trichogyne" is a cell cut off from the 

 ascogonial cell. When fertilization takes place, the wall between the two 

 cells breaks down to allow the passage of the male nucleus, but closes up 

 when the process is effected. In Pyronema confluens^ it is represented by a 

 process from the ascogonial cell which fuses directly with the male cell. A 

 more elaborate "trichogyne " has been evolved in Lachnea stercorea', another 

 Discomycete: in that fungus it takes the form of a 3-5-septate hypha with 

 a longer terminal cell; it rises from some part of the ascogonial cell but has 

 no connection with any process of fertilization, so that the greater elaboration 

 of form is in this case concomitant with loss of function. 



In the Laboulbeniaceae, a numerous and very peculiar series of Asco- 

 mycetes that live on insects, there are, in nearly all of the reproductive bodies, 

 a carpogonial cell, a trichophoric cell and a trichogyne. The last-named 

 organ is in some genera a simple continuous cell, in others it is septate and 

 branched, occasionally it is absents The male cells are spermatia of two 

 kinds, exogenous or endogenous, and'the plants are monoecious or dioecious. 

 Laboulbeniaceae have no connection with lichens. Faull^ a recent worker 

 on the group, states that though he observed spermatia attached to the tri- 

 chogynes, he was not able to demonstrate copulation (possibly owing to 

 over-staining), nor could he trace any migration of the nucleus through the 

 trichophoric cell down to the carpogonial cell. In two species of Laboulbenia 

 that he examined there were no antheridia, and the egg-cell acquired its 

 second nucleus from the neighbouring trichophoric cell. These conjugate 

 nuclei divided simultaneously and the two daughter nuclei passed on to the 

 ascus and fused, as in other Ascomycetes, to form the definitive nucleus. 



Convincing evidence as to the importance of the trichogyne in fungi was 

 supposed, until lately, to be afforded by the presence and functional activity 

 of that organ associated with spermogonia in a few Pyrenomycetes — in 

 Poronia, Gnomonia and Polystigma. Poronia was examined by M. Dawson* 

 who found that a trichogyne-like filament distinct from the vegetative hyphae 

 rose from the neighbourhood of the ascogonial cells. It took an upward 

 course towards the exterior, but there was no indication that it was ever 

 receptive. In Gnomonia erythrostoma and in Polystigma rubrum, spermogonia 

 with spermatia — presumably male organs — are produced in abundance shortly 

 before the ascosporous fruit is developed. The spermatia in both cases exhibit 



'■ Schikorra 1909. ^ Harper 1900. ^ Fraser 1907. ■* Thaxter 1912. 



^ FauU 191 1. o Dawson 1900. 



