CHYTRIDIE.E. 199 



" The Chytridia form a genus of unicellular, parasitical Algre, or, if it 

 be preferred, of aquatic Fungi, related to Saprolegnia about as much as 

 Ascidium is to Bryojjsis. The entire plant is composed of a single balloon- 

 shaped cell, which penetrates into the Algas upon which it grows, by a 

 more or less developed root-like base. The inflated portion of the cell is 

 filled with colourless mucilage, from which are formed, not through suc- 

 cessive division, but by a simultaneous process, very numerous small 

 globular germ-cells, which exhibit a sharply-defined darker nucleus in the 

 interior, and possess a single very long cilium. From their want of 

 colour and the activity of their motion these gonidia resemble the most 

 minute monads. Their extrusion occurs either through the casting off of 

 a lid or through mere tearing of a nipple-shaped point. Of fifteen different 

 species which I have observed in the vicinity of Freiburg, Chytridium 

 olla is the largest, and at the same time exhibits the lid-like dehiscence 

 most beautifully. It grows on the anterior wrinkled end of the bulging 

 parent-cells of the spores of (Edogonium Landsboroughii, the root pene- 

 trating into the folds and attaching itself to the spore. The free inflated 

 portion of the cell is ovate, with the lid somewhat thrown up at the 

 edges, and apiculated like a short nipple in the middle. The germ-cells 

 are about '003 mm. diarn." Braun, Rejwenescence, pp. 186 note. 



See also Braun, " Ueber Chytridium " (Berlin, 1856) ; Cohn in " Hed- 

 \vigia," 1865, p. 170 ; Nowakowski " Beitrag zur Kenntniss der Cbytri- 

 diaceen ' (Breslau, 1876). 



Chytridium acuminatum. Braun Chytr. p. 28, t. 1, /. 11. 



Cells much smaller than in Chytridium olla, ovate-pyriform ; 

 operculum acuminate. 



SIZE. Cells '016 mm. long. 

 Eabh. Alg. Eur. iii., p. 277. 



Parasitic on species of QZdogonium. 



Plate LXXXI. jig. 1. Chytridium acuminatum parasitic upon (Edo- 

 gonium Rothii X 400 diam. 



GENUS 77. RHIZOPHYDIUM. Schenk. (1858.) 



Cells globose, ovate, or broadly clavate, with 2, 3, or more 

 scattered orifices, more or less elongated into a neck, furnished 

 with, or destitute of, distinct radicles at the base. 



Rhizophydium Barkerianum. (Archer.) Eabh. Alg. Eur. in. 281. 



Cells much depressed, 3 or 4 lobed, the lobes broadly rounded ; 

 upper surface of the cell concave, bearing at the centre a ver- 

 tical hyaline, very slender, terete, minutely capitate process ; 

 cell contents mainly confined to the centre, leaving the ends of 

 the lobes empty ; zoospores making their exit through the 

 opened apices of the lobes. 



Chytridium Barkerianum, Archer in Quart. Journ. Micr. Sci. 

 1867, p. 89. 



Parasitic on Zygnema. Gallery Bog (Ireland). 



We have seen no specimens, and are not aware of any figure extant, or 

 of any dimensions having been recorded. 



2 F 



