OOMYCETES 59 



these branches are rare, she suggests that the oospores probably develop 

 parthenogenetically. 



In addition to the sporangia, characteristic hypnospores, which 

 fall off at maturity and leave scars on the sporangiophores, have been 

 observed, e.g., in B. Pringsheimii (Fig. 35, 5). In Allomyces arbuscula 

 these hypnospores arise inside the terminal segment (Fig. 35, 3). Their 

 morphological significance is still puzzling. Butler (1911) regards them 

 as parthenogenetically developed oospores which find their analogues in 

 the endogenous species of Monoblepharis. 



Finally the only parasite in this group, Jaraia Salicis (Nemec, 1911), 

 on root tips of Salix purpurea in Czechoslovakia, lacks differentiation 

 into primary and secondary shoots, and segmentation of the sporiferous 

 hyphae. It possesses antheridia and oogonia; in the latter there arise 

 as many as 50 rather thin-walled zoospores. Further investigation 

 would give interesting results. 



Ancylistaceae. — At present only aquatic forms on pollen grains, 

 algae and animals are known. Because of their simple thallus and holo- 

 carpy, some authors place them in the Chytridiales; however, since 

 they form oospores, they undoubtedly belong to the Oomycetes. Here 

 also relationships are obscure, particularly because the exact processes 

 before and after fertilization are insufficiently known. They are con- 

 sidered by A. Fischer (1882), Schroeter and Scherffel (1925) as ascending 

 forms which lead from the Archimycetes and Chytridiales to the Oomy- 

 cetes. Scherffel bases this conception on his observations concerning the 

 diplanetism of Ectrogella, which he connects directly to the shedding 

 of the membrane as described for Phlyctidium (p. 36). It is a question 

 whether Ectrogella forms true oospores or whether it does not rather 

 behave as Zygorhizium, Pseudolpidiopsis, etc. (empty appendiculate 

 cells in E. Licmophorae!). Further, their zoospores are not reniform 

 with a true lateral insertion of flagella, as in the true Ancylistaceae, but 

 pyriform with more or less terminal flagella. Hence it is quite possible 

 that Ectrogella does not belong to the Oomycetes and, in spite of its two 

 flagella, should be classified with the Chytridiales. In this case, the 

 main support for deriving the Ancylistales from the Chytridiales would 

 be removed ; also Ectrogella would take a more significant position in the 

 Chytridiales as it would explain the peculiar collecting of zoospores at 

 the mouth of the emission collar. 



Bary and Tavel, on the other hand, regard the Ancylistaceae as 

 simple or simplified Pythiaceae. This conception appears nearer the 

 truth, as in the better-known genera, with the exception of Ectrogella, 

 the zoospores possess laterally inserted flagella. I prefer not to regard 

 them an ascending line, as one cannot imagine how the less complex soil 

 saprophytes, like the Aphragmium group of Pythium, have arisen from 

 such parasites as Ancylistes and Myzocytium; but I prefer to consider 



