310 



THE LOWER FUNGI— PHYCOMYCETES 



terminal cluster. The spore sac and the conidium are clearly- 

 one fundamental structure undergoing two types of germination. 

 Even in proliferation a conidium may form within the old sac 

 after the escape of the spores. 



The genus was founded on a single species, A. ruhescens 

 Brefeld (1891) isolated from a slime flux of beech in Germany. 

 A single other species, A. saprolegnoides Holtermann (1898) was 

 described from Java where it was found forming a brownish 

 encrusting mat on various trees. In the first species the spores 



Fig. 110.- — Ascoidea ruhtticens Brofeld. (n, l>, d) Spore-sacs proliferating:. 

 Spores freed in an oily matrix, (c) Hat-shaped spores. (From unpublished 

 drawings by Leva B. Walker). 



are hat-shaped and lie in the sac with the flattened sides together. 

 They are extruded in a long coiling thread-like mass. The 

 second species as described differs chiefly in having globose to 

 oval spores, not in pairs, which when extruded do not form a 

 thread. In A. ruhescens the empty walls of several spore sacs 

 commonly are found nesting one within the other. In A. sap- 

 rolegnoides, elongation of the thread is said to result usually 

 in the formation of each successive sac beyond the limits of its 

 predecessor. In spite of these described differences it is possible 

 that the two species are the same. The hat-shape of the spore 

 is not always observed with ease in ^. ruhescens, and may actually 

 occur in Holtermann 's species. 



