96 THE SAPROLEGNIACEAE 



ture of the eggs and the form of the antheridial branches and antheridia. 

 One of the species heretofore included we have removed to our new 

 genus Proloachlya. As it remains after this removal, the genus Achlya 

 contains four primary groups that we are considering as sub-genera, 

 under the more typical of which one may recognize two well-defined 

 assemblies. One of the sub-genera {Centroachlya) is so sharply delimited 

 as easily to qualify for a new genus were one inclined to make it. 

 As small and numerous genera are a nuisance to everyone except the 

 most extreme specialist (and a nuisance to him except in his own field) 

 we gladly refrain from increasing the number any further than seems to 

 us necessary in order to retain a clear conception and definition of the 

 old genus Achlya. Achlya paradoxa, which we are removing to Pro- 

 toachlya, is not a good Achlya, as a part of its spores swim away on 

 emerging. 



As to the correct position of A. glomerata there is some doubt. Its 

 odd little oogonia, single egg, and antheridia as in the Racemosa group 

 seem to set it off distinctly. It may be a lead toward Aphanomyces. 



As the words centric and eccentric have both been used to cover 

 quite different organizations of the eggs, one must await more careful 

 study to be sure of the position of certain European species in which the 

 eggs are described as centric or weakly eccentric. 



In attempting to put into order the members of the ProliJera-deBary- 

 ana group we meet with some of the most perplexing problems in the 

 entire family. Either deBary was entirely too rigid in his descriptions 

 of A. prolifera, and A. deBaryana (his A. polyandra) and failed to allow 

 for a certain amount of normal variation, or there are more than five 

 times as many species or sub-species (or what not) in the close group 

 represented by these two species than he described, a fact not sur- 

 prising in itself if it were not for certain strange inconsistencies in their 

 distribution. 



With the great majority of the good species of the older European 

 botanists already known to occur in America with little or no discrep- 

 ancies, it is odd indeed that A. prolifera and A. deBaryana, the two most 

 common European Achlyas (according to deBary, Fischer, Minden and 

 others), should so far not have been recognized in America. Instead 

 we have several species (or forms) very close to them, indeed, but failing 

 to agree with them in one or more characters most emphasized in their 

 descriptions. Achlya prolijeroides is just like A. prolifera except that 

 the antheridial branches are not always diclinous and do not wrap them- 

 seh'es so extensively about the oogonia, and the number of eggs in an 

 oogonium is small, nearly always two to six. On the other hand, among 

 their many striking resemblances they are the only two species we have 



