1 86 THE SAPROLEGXIACEAE 



Rhizophidium carpophilum (Zopf) Fischer. Rabenhorst's Krypt. Fl. 1. 

 4: 95. 1892. (2nd. ed.). 

 Rhizidiiim carpophilum Zopf. Nova. Acta. Acad. Leop. 47: 200, 

 pi. 20, figs. 8-16. 1884. 



Plate 62, figs. 11-13 



Sporangia subspherical, seated on the surface of the oogonia of the 

 host, varying greatly in size and number, about io-30iJ. in diameter, 

 emptying through a more or less apical, thin-walled, short beak which 

 seems to break and then collapse and disappear; spores very minute 

 and nearly hyaline except for one or two dots, swimming rapidly. They 

 emerge singly and from their own efforts, and dash around madly inside 

 the sporangium when the beak opens, seeming to find the way out purely 

 by accident. It usually takes several minutes for all to get out; cilia 

 number not determined (said to be one). Sporangia attached to the 

 swollen tip of a mycelial thread which branches farther down and enters 

 the eggs of the host and eventually destroys them. Certain of the 

 smaller sporangia do not discharge at once, but go into a resting state, 

 the contents becoming compacted into a dense refractive body. 



Observed several times in Chapel Hill, where it is parasitic on the 

 oogonia of Achlya apiculata, A. flagellata and A. conspiciia. The eggs of 

 the host become defined, in all cases we have seen, before being dis- 

 organized, and usually they are not all attacked, one or several arriving 

 at healthy maturity amid the detritus of those destroyed. 



The present plant agrees well with R. carpophilum as described 

 and figured by Zopf, except that the hypha entering the oogonium is 

 thicker than he shows. Rhizidiomyces apophysatus differs in the swell- 

 ing just inside the oogonium wall, in the long and more persistent empty- 

 ing beak and in the emergence of the spores in a bladder. 



Rhizidiomyces apophysatus Zopf. Nova Acta Acad. Leop. 47: 188. pi. 

 20, figs. 1-7. 1884. 



Plate 63 



Sporangia spherical to subspherical, varying greatly in size, from 

 10 to 45IA thick; seated on the surface of the oogonia of the host and 

 communicating with the interior of the oogonia by means of a tube- 

 like body which may expand into an internal bladder (which may measure 

 as much as iS.S-x thick) from which numerous rhizoid-like structures 

 arise and penetrate the eggs or mingle with the oogonial contents. Spore 

 initials appearing early and then disappearing by complete coalition to 

 reappear only after discharge into an apical bladder. Spores discharged 

 somewhat as in Pythium, the spore mass passing out through a thin- 

 walled tube, one to three times as long as the diameter of the sporangium, 

 which expands at the tip into a very delicate bladder into which the 

 spore mass flows. Here the spore initials gradually appear again and 

 complete their development. Before discharge they show a distinct 



