CHAPTER V. COMPARATIVE REVIEW. CHYTRIDIEAE. 169 



is in this case indispensable ; it is not easy to manage but still it is not impossible. 

 Observation should be directed also to the origin of the initial cells of the sori as well as 

 to that of the resting-cells, for there is no apparent reason why the latter should arise 

 without and the former with conjugation. It should also be extended to more than one 

 species, for the oogonia and antheridia of the Saprolegnieae show that what is the rule 

 in one species is not so necessarily in another. If we were prepared to draw arguments 

 for the formation of sori by conjugation from isolated facts, we might find them in the one 

 which was first observed by Schroter, that there is a broad empty brownish-looking 

 membrane adhering to one side of every full-grown sorus in Synchytrium Stellariae and 

 S. Succisae inside the swollen cell of the host. Schroter, however, gives a different 

 and probably the true explanation of this circumstance ; he supposes that a vesicle 

 which takes up the protoplasm issues out of the original membrane of the initial cell 

 shortly before the formation of the sorus, as in the germination of the resting-cells of 

 Pycnochytrium, but this has not however been directly observed. 



The course of development in the genera Woronina and Rozella, Cornu, is very like 

 that of the Synchytrieae ; in outward appearance, as parasites of the Saprolegnieae, 

 they are certainly sufficiently unlike the Synchytrieae which inhabit Phanerogams. 

 A. Fischer's complete investigations have distinctly proved the absence of conjugation 

 and sexuality in these genera ; for a detailed account of them the reader is referred 

 to Cornu and A. Fischer. Their very peculiar mode of life will be noticed in 

 Division III. 



SECTION LI. If we compare the facts of development in these four groups with 

 those in other Fungi, we see that the chief points of connection with the latter are to be 

 found in the first group. Polyphagus may at once be put side by side with the Mucorini 

 as a very small form adapted to a submerged life by the formation of swarm-spores ; 

 the connection is still more perfectly effected by Zygochytrium, which ranks with 

 the Mucorini as truly as with Polyphagus, if Sorokin's statements are confirmed (see 

 page 156). The homologies are sufficiently brought out by the terminology employed. 

 There are also obvious points of connection with the Ancylisteae (page 139). Of the 

 other groups the Cladochytrieae come nearest to the Rhizidieae, even if sexual pro- 

 cesses are really wanting in them and are not merely undiscovered. It is possible 

 that some of the Rhizidieae themselves may be in the same condition. With a similar 

 supposition necessary at present, we may regard the two other groups as nearly 

 related to the Rhizidieae, if we consider them to be forms in which the formation 

 of rhizoids or mycelia has fallen into disuse, or been entirely lost, in consequence 

 of special and intimate parasitic adaptation ; the Olpidieae will then come nearest to 

 the Rhizidieae, and there is no difficulty in connecting the Synchytrieae with 

 the Olpidieae. In this view of the subject the whole division of the Chytridieae 

 would be regarded as a lateral branch either of the Mucorini or of the Ancylisteae, 

 which has been gradually simplified in correspondence with its submerged parasitic 

 life and has reached its most specialised condition, in which it differs most from 

 the preceding divisions in Woronina and Rozella, genera of the Synchytrieae. 



On the other hand the resemblance of the simple Chytridieae without rhizoids 

 to unicellular Algae, especially the Protococcaceae, Characium, Chlorochytrium, &C. 1 , 

 has always been recognised. The question of course arises whether this resemblance 

 is the expression of close phylogenetic affinity, or only of analogous adaptations ; for 

 apart from the presence of chlorophyll, the conjugation of swarm-cells which prevails 



1 See Klebs in Bot. Ztg. 1881, p. 249. 



