» 



REVISION OF ENDOGONEAE. 311 



form. The species Is, however, a well defined Endogone. The spore- 

 groups -are smaller and more clearly defined than those of E. tubercu- 

 losa. Spegazzini remarks that the spore-groups are never confluent; 

 but a section from the dried material shows that they are not always 

 distinguished with great clearness, and are at least often in close 

 contact. 



The spores, unlike those of E. tuberculosa, are reddish brown, con- 

 siderably smaller and more nearly spherical, though usually irregular 

 from mutual pressure. Their greatest diameter seldom exceeds SO /x, 

 while that of E. tuberculosa is often as much as 125 m- The gleba is a 

 dirty brownish yellow with a reddish tinge, horny when dry, the 

 strand which separates the spore-groups, which are not always clearly 

 marked, having a darker brownish color. The gleba, unlike that of 

 E. tuberculosa, is continuous in the sense that, as far as I have seen, it 

 contains no incorporated foreign matter. 



The origin of the spore-groups is quite remarkable, and I have had 

 some difficulty in making it out, owing to the scantiness of the material 

 which it was essential to injure as little as possible. Their origin 

 seems unassociated with any sexual process, and careful examination 

 of a section shows that the spores, which are practically sessile, origi- 

 nate by budding in all directions from an enlarged hyphal termination. 

 In the fully mature condition which characterizes the type, this 

 termination is very thick-walled and irregular in outline. At points 

 where a spore-group has been cut nearly through the middle, one may 

 see sections of these thick-walled terminations with one or more 

 definitely related spores in situ, as indicated in Figure 34:. Each 

 termination appears to produce as many spores as can be crowded 

 around it, and when the group is viewed from without, it is quite 

 impossible to see any indication of their mode of origin. Although a 

 multiple origin of zygospores from a single conjugation is not neces- 

 sarily excluded as a possibility in this instance, and might find a cer- 

 tain analogy among the Entomophthorales where two distinct zygo- 

 spores may be produced in this manner, it may be assumed that the 

 process in this instance is purely asexual and that it is merely a more 

 specialized manifestation of that which occurs in E. fasciculata, in 

 which, owing to the loose texture of the general mass, the spores, 

 although arising in crowded groups, are produced in a more nearly 

 normal fashion. This conclusion is further supported by the structure 

 of the individual spores which lack a continuous endospore. A 

 majority of the spores are attacked by a sterile parasite similar to 

 that mentioned in the preceding species and shown in the spore at the 

 right in Figure 34. 



