4 TEXT-BOOK OF FUNGI 



sexual reproduction, inasmuch as invigoration or rejuvenes- 

 cence is concerned. 



Before leaving the subject of sexual reproduction, one 

 more important discovery requires notice. In certain 

 fungi both antheridium and oogonium contain numerous 

 nuclei, sometimes one hundred or more each. 



The male miclei pass into the oogonium, where the 

 male and female nuclei fuse in pairs, the result being 

 a considerable number of nuclei present in the oospore. 

 Stevens has shown that this occurs in certain species of 

 Cystopus, belonging to the Phycomycetes, and Harper has 

 demonstrated the same in Pyronema confluens, belonging 

 to the Ascomycetes. 



The significance of this discovery is not at present 

 obvious, but the fact that in both groups, and even in 

 other species of Cystopus, or Albugo, as it is termed by 

 American writers, fusion of a single male and female 

 nucleus in the oosphere exists, should at least act as a 

 check on those who are prone to jump to conclusions, 

 and draw up phylogenetic diagrams from a limited amount 

 of evidence. 



Concerning affinity and descent much has been done of 

 late years, and if the conclusions arrived at cannot be 

 considered as final, they are at least suggestive, and furnish 

 facts which may eventually go towards substituting 

 homology for analogy. 



Brefeld considers the sporangium of the Mucorineae 

 and the asci of the Ascomycetes as homologous organs, 

 and that the latter are derived directly from the former. 

 The recent researches of Leger, Swingle, and Thaxter on 

 the mode of spore formation in the Mucorineae, and of 

 Harper in the Ascomycetes, are considered not to support 



