﻿S32 BOTANICAL GAZETTE [may 



shown in any other type and has important bearings on the 

 possible development of tissues of considerable complexity by 

 the coenogamete. 



But many difficulties present themselves when the Monoble- 

 pharidae are made a starting-point for a line of ascent to the 

 Peronosporales, as is done by Trow (1901, pp. 306, 307) when 

 he arranges in series Monoblcpharis, Saprolegnia, Pythium, and 

 Albugo (Cystopus). These forms are not so similar that 

 close relationships are manifest either through morphology or 

 ontogeny. Under the most favorable interpretation it must be 

 granted that they are at present widely divergent and highly 

 specialized types, even assuming that ancestral forms now 

 extinct might have had more general characters. Such specu- 

 tions are, of course, entirely justifiable, if they do no violence to 

 developmental history. 



However, as has been shown, such an evolution must assume 

 either that uninucleate gametes became multinucleate or that 

 differentiated eggs' (Monoblcpharis) lost their high state of 

 specialization and finally their entire individuality in the coenoga- 

 mete of the Peronosporales. Both processes are opposed to 

 what we know has been the evolutionary history of sexual cells 

 in several divergent and independent groups of algae. We are 

 called upon to accept a ** subjective phylogeny" opposed to well- 

 established cytological processes. 



The situation is somewhat similar to that presented to the 

 Brefeldian school with respect to the origin of the ascus from 

 the sporangium of a mold. Harper has shown that the proto- 

 plasmic activities of sporogenesis in the sporangium and ascus 

 are along entirely different lines with nothing in common. To 

 the writer such differences in cytological processes completely 

 outweigh conclusions from any series of types presented on a 

 basis of general form resemblance. Form resemblance between 

 the ascus and sporangium can have very little morphological 

 value until it be accompanied by evidence satisfactorily explain- 

 ing the differences of protoplasmic organization and behavior. 

 And the elaborate phylogenetic structure built by Brefeld and 

 his followers is sadly in need of a foundation, if not already a 



