﻿32 2 BOTANICAL GAZETTE [may 



the Saprolegniales and Peronosporales are ** ph^^logenetic renii 

 niscences of the formation of gametes." The attempts to estab- 

 lish special functions for these mitoses as reduction divisions for 

 the eggs have been unsuccessful. 



The oogonia and the antheridia of the Peronosporales, Sap- 

 rolegniales, and Pyronema are the homologues of gametangia, 

 and consequently of that simplest type of coenogamete, as illus- 

 trated in the Mucorales. There is everything in the morphology 

 of these structures to favor these conclusions, but only recently 

 have we known the details of protoplasmic organization. When 

 an entire gametangium functions as a gamete, as in the Muco- 

 rales, it becomes a coenogamete. In Pyronema, Albugo, and 

 the multinucleate eggs of the Saprolegniales the coenogametes 

 are restricted portions of the protoplasm in such gametangia, 

 but it is obvious that in Pyronema and Albugo, the gametan- 

 gium behaves as a whole in a manner strictly similar to the 

 fusion of the coenogametes in the Mucorales. It should be noted 

 that these homologies are quite independent of the problem of 

 the origin of the coenogametes in the various groups. That 

 topic will be treated in the next section of the paper. 



Stevens (1901) has carried the homologies a step farther in 

 suggesting that the receptive papilla from the oogonium of the 

 Peronosporales marks the position of the pore that develops in the 

 gametangia of algae to give entrance or exit to the sexual ele- 

 ments. This is a very interesting comparison and is worth fol- 

 lowing to its limits. Thus the points of fusion of the coenoga- 

 metes of a mold may be homologous with the points of exit of 

 the motile gametes from the gametangium of some algal 

 ancestor. 



The term '* coenogamete " should be employed in the strict 

 sense indicated when the term was proposed (Davis, 1900, p. 

 307). It is a structure containing more than one gamete \ 



nucleus, and generally very many functional or potential gamete 

 nuclei. It is generally homologous with a gametangium, the 

 binucleate and trinucleate eggs of the Saprolegniales and the 

 multinucleate eggs of Sphaeroplea anmilina Braunii (Klebahn, 

 1899) presenting the only exceptions, for the oogonia of Albugo 



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