ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 283 



Ancylistese and Chytridiaceae.* — Dr. W. Zopf describes in detail the 

 structure and life-history of the following fungi parasitic on various species 

 of Zygnema, Mougeotia, Spirogyra, Cladophora, diatoms, Saprolegnia, and 

 other fresh-water organisms, viz. : — Lagenidium Bahenhorstii, L. entopliyllum, 

 Myzocytium proliferum, M. proliferum var. vermiculum (on nematoid worms), 

 Olpidiopsis Schenkiana, Pleotrachelus fulgens, Ectrogella Bacillariacearum, 

 Amcebochytrium rJiizidioides, HypTiocytium infestans (on a Peziza), BJiizidio- 

 myces apopJiysatus, BMzidium intestinum (on Nitella), B. hulligerum, B. Cien- 

 Jcowskianum, B. Fusus, B. carpophilum, B. spJisei-ocarpiim, B. appendiculatum 

 (on a Palmellacea), B. apiculatum, and B. acuforme. 



Dr. Zopf adopts Pfitzer's classification of the genera Ancylistes, Lage- 

 nidium, and Myzocytium into a distinct family under the name Ancylistese, 

 distinguished from the rest of the Saprolegniacese by the circumstance 

 that the existence of the vegetative organ as such closes with the develop- 

 ment of the fructification, the mycelial tube being entirely used up in the 

 formation of the sporangia or of the sexual organs ; while in the higher 

 Oosporese the mycelium may even continue to develope after the formation 

 of the fructification. The mycelium is in this group always very feebly 

 developed, and in Myzocytium is almost entirely suppressed ; while in the 

 higher Saprolegniacese and Peronosporese it attains to the dignity of a 

 copiously branched mycelial system. 



A third characteristic of the group is in the mode of formation and escape 

 of the swarmspores, at present known only in Ancylistes, and agreeing more 

 with Pythium than with Saprolegnia. The zoospores are perfectly formed 

 only outside the sporangium, in the vesicle formed by the tumidity of its 

 inner cell-wall. A further distinction from both Saprolegniacese and Pero- 

 nosporesB consists in the process of impregnation. "While in both these 

 groups the oosphere is completely formed before impregnation, in the 

 three genera under discussion this takes place only during and subsequently 

 to that process ; and, instead of only a portion of the contents of the 

 antheridium being required for the purpose of impregnation, the whole 

 passes over into the oogonium. Again, while in the Peronosporese only a 

 portion, in these genera the whole of the protoplasm of the oogonium is 

 used up in the formation of the oosphere. 



These peculiarities of structure are held by Dr. Zopf sufficient to 

 justify the formation of a separate group of Ancylistese out of three 

 genera, although the process of impregnation has not yet been observed 

 in Lagenidium, and only imperfectly in Myzocytium. But the process, as 

 known in Ancylistes, forbids the idea of a very close affinity between this 

 group and the Pythie^e ; it much more nearly resembles a process of true 

 conjugation than in that family. 



While the Ancyliste^e exhibit an affinity upwards with the higher 

 Oosporese, they are also connected downwards with the Chytridiaceae, and 

 especially with certain Olpidiese. This is well seen in the resemblance 

 between the reduced neutral and sexual individuals of Myzocytium proUferum 

 on the one hand, and between the neutral and sexual individuals of Olpidiopsis 

 ScJienJciana on the other hand. This resemblance is so great, that uni- 

 cellular sporangial plants of the former species cannot be distinguished 

 from sporangia of the latter, when both are still unripe or already dis- 

 charged. There is a similar close resemblance between the mycelial tube 

 of Ectrogella and that of Ancylistes. 



On these grounds the author suggests that the Olpidiese are possibly 



* Verhandl. K. Leop. Carol. Deutsch. Akad. Naturforsclier, xlvii. (1885) pp. 111-236 

 (10 pis.). 



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