26 SEXUAL REPRODUCTION IN CERTAIN MILDEWS. 



MORPHOLOGY OF THE ASCOCARP. 



Considerable further evidence that the ascocarp originates in a 

 functional sexual apparatus has accumulated in recent years. Miss 

 Dale ( 18) has shown conclusively that a fusion of gametes occurs at the 

 origin of the ascocarps of Gymnoascns Reesii and Gymnoascus candi- 

 dus, and concludes that the normal method of origin of the fruit bodies 

 of the Gymnoascaceae and their related forms is by the union of two 

 cells of more or less widely separated origin. Monascus is a very inter- 

 esting object of investigation and its affinities have been quite variously 

 interpreted. Barker's (3) complete and consistent account and the 

 more recent briefer one by Olive (72) agree in describing the origin of 

 the asci from ascogenous hyphse and an ascogonium, so that we may 

 probably conclude that it belongs among the Ascomycetes. Barker, 

 Ikeno, and Olive maintain the existence of a sexual cell-fusion, while 

 Kuyper (55, 56) and Dangeard (20) deny that any such process occurs. 



Ikeno's account of two successive free-cell formations in the asco- 

 gonium seems highly improbable, though Kuyper agrees with him on 

 this point. Neither Ikeno's nor Kuyper's figures are, however, con- 

 vincing, and to establish the existence of a process of forming asci or 

 spore mother cells, as well as ascospores, by free cell-formation cer- 

 tainly demands the presentation of a detailed account with good figures 

 of the stages involved. If the asci or "spore mother cells" of Monascus 

 are formed by free cell-formation, it is certainly evidence against its 

 close relationship with the Ascomycetes. Kuyper believes it should be 

 made the representative of a new family, the Endascineae, connecting 

 the Ascomycetes to the Oomycetes. Ikeno probably calls these bodies 

 " spore mother cells " on an assumed analogy between them and the 

 cells formed by free cell-formation in Taphridium, to which Juel (51) 

 has given this name. It is to be remembered, however, that these "spore 

 mother cells " of Taphridium form spores not by free cell-formation, 

 but by ordinary division. It is hard to see how Ikeno's account of 

 spore formation gives any basis for his conclusion that his Monascus 

 has relations with the other so-called Hemiasci. Kuyper indulges in 

 some very sharp criticism of the lack of homogeneity of this group, 

 which is doubtless justified, though we are more in need of new facts 

 about the forms in question than of a priori criticism. Still later papers 

 by Barker (4) reaffirm the correctness of his account of the reproduc- 

 tion of Monascus and add a preliminary account of sexual cell fusion 

 in the development of the ascocarp of Rhyparobius. In this form we 

 find a fusion of gametes with several nuclei. The ascogonium develops 



