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1903] OOGENESIS IN SAPROLEGNIA 329 



Phycomycetes discussed in the previous sections of this paper. 

 To derive a multinucleate gamete (Pyronema) from a uninucleate 

 (Sphaerotheca) involves an evolutionary process quite unknown 

 to botany. To deriv^e a uninucleate gamete from a coenogamctc 

 merely demands a gradual reduction of the number of gamete 

 nuclei, a process which we know to have taken place in several 

 groups of algae independently of one another, and one which is 

 beautifully shown in Stevens's series of four species of Albugo. 

 Harper (1900, pp. 388, 389) seems to be undecided as to the 

 developmental relation of conditions in Sphaerotheca to such as 

 are presented in Pyronema. He shows that the oogonium of 

 Sphaerotheca could easily be given the form of Pyronema by the 

 development of the beak into a conjugating tube with some 

 minor changes in the position of the antheridium. But he dis- 

 regards the internal changes necessary to derive a coenogamete 

 from a uninucleate gamete. And at the end of the same para- 

 graph he says: *' Still I am inclined to believe that the reverse 

 process has taken place and that the sexual apparatus with the 

 trichogyne represents the more primitive type for the Ascomy- 

 cetes/' To the writer resemblances of form have very little 

 value in such comparisons, and relationships must be traced 

 through agreement in the details of protoplasmic activities. And 

 again, as Harper points out, the general morphology of the Ery- 

 sipheae is much higher than that of Pyronema. But Professor 

 Harper by his last statement has warded off criticism, and per- 

 haps, with the evidence from Albugo and Saprolegnia before 

 him, he will feel more certain, with the writer, that the coenoga- 

 mete when related to the uninucleate gamete always represents 

 more primitive conditions. 



And this conception has a very interesting relation to the 

 possibility of deriving the trichogynes of lichens and the 

 Laboulbeniaceae from a primitive type of sexual organ that may 

 have been a coenosramete. Of course, there is no reason why a 

 uninucleate gamete (archicarp) among the fungi might not 

 develop a simple trichogyne, as has been done in the Rhodophy- 

 ceae, but the trichogynes of the lichens and the Laboulbeniaceae 

 are generally systems of cells quite distinct from the female 



