Miscellaneous. 387 



renal organ of Aseidians of the family Molgulidoe. But in the latter 

 animals the symbiotic Fungi belong to a group much higher than 

 the Schizomycetes. The older writers have described and imper- 

 fectly figured foreign bodies iu the kidney of the Molgulidse, calling 

 them.confervoid filaments, gregariniform bodies, &c., and supposing 

 them to belong to diverse creatures *. In reality these productions 

 must be referred to Fungi of the tribe Siphomycetes (Sorokine) and 

 of the family Chytridineie. The parasites of the various species of 

 Molgulidse belong to different species, but in the same species of 

 Ascidia we generally find only one species of parasite in very various 

 stages of evolution. I give these Fungi the generic name of Nejjhro- 

 mi/ces. The most nearly allied genus seems to me to be Catenaria, 

 Sorokine, the type species of which, Catenaria angxdlluke, is para- 

 sitic upon Nematoda. However, in JSephromyces the sporangia are 

 always terminal. 



I have particularly studied two species of Xephromyces having as 

 their hosts two Molgulidae which are very common at Wimereux : — 

 1. Nephromyces Molyularum, parasitic upon Molgula socialis. 

 Alder ; and 2. Nephromyces Sorohini, a parasite of Lithonephrya 

 euf/yranda, Lac.-Duth. 



Nephromyces Mohjidarum forms around the isolated concretions 

 which fill the kidney of Moh/ida socialis a unicellular mycelium 

 with very delicate filaments strongly felted together, the free extre- 

 mities of which are terminated by spheroidal dilatations ; notwith- 

 standing their appearance, I have never seen these terminal swellings 

 detach themselves fi'om their support and behave like conidial spores. 



This delicate, transparent mycelium produces a great number of 

 much thicker tubes of irregularly cylindrical form, more or less 

 contorted upon themselves, and filled with a finely granular opaque 

 protoplasm which is strongly stained by picrocarmiue. Side by 

 side with these protoplasmic masses originate, in enormous quan- 

 tity, zoosporangia of very varied forms, often bifurcated at their free 

 extremity, and in these are developed a multitude of very active 

 zoospores of excessively small size. The formation of the zoospores 

 is preceded by a spumous appearance of the protoplasm, such as 

 has been indicated in various Chytridinese, and by the formation of 

 thicker septa separating the sporangium from the rest of the myce- 

 lium. For a long time I had only a very imperfect notion of these 

 zoospores, and I have been able to make anything of their study 

 only by the aid of Zeiss's excellent apochromatic objectives. The 

 zoospores are perfectly spherical, and furnished with a pretty long 

 but very slender flagellum ; they contain a strongly refractive 

 granule towards the origin of the flagellum. It is probable that 

 these active bodies introduce themselves into the branchiae of the 

 young Ilolyidif, and penetrate by diapedesis into the renal organ, 

 since neither by injections nor by sections has any opening been 

 found into that organ. 



* Lucaze-DutLitr.s, Arch, du Zool. exj er. et j,eii. tome iii. pi. xi. (1874). 



