ENTOMOPHTIIOREAK OF THE UNITED STATES. 



147 



The simplest process by which azygospores arc formed is presented by the case in 

 which the contents of a hyphal body become directly converted into a resting spore 

 usually contracting somewhat and surrounding itself with two walls, the normal third 

 wall being represented by that of the hyphal body, within which the spore may be en- 

 tirely free, or to which it may be closely applied. A modification of this process occurs 

 sometimes in the case of chlamydospores, which may be transformed directly into azyg- 

 ospores by the deposition of a third inner wall. 



Azygospores may also be formed in a variety of ways from hyphae of germinat ion aris- 

 ing from chlamydospores or hyphal bodies, or not uncommonly by direct lateral budding 

 from them. In the first case the azygospore may be terminal (fig. 40), at the apex of a 

 hypha of greater or less length, or may bud lat erally. This process, which may be read- 

 ily seen by cultivating chlamydospores in water, resembles at first the analogous forma- 

 tion of conidia; the end of the hypha, however, does not produce a bud, but becomes 

 swollen into a mother cell, which is not separated from the hypha by a cross partition, 

 and within which the double-walled spore is formed. Still another method consists in 

 the production of azygospores interstitially (fig. 81), which is common in certain species 

 and leads to the occurrence of spores having very irregular shapes. 



These in general are the more common types of azygosporic formation, of which there 

 are numerous slight modifications. Where true zygospores are formed, a considerable 

 amount of variation is exhibited in the process as it occurs in different species ; and al- 

 though the sexnal nature of the spore is beyond question in some instances, it is not so 

 well marked in others, and may, as ]^ow r akowski has suggested, represent a transitional 

 form from the truly sexual to the wholly asexual processes. Such instances are found 

 in E. sp7iaerosperma, a species in which, according to Brefeld, the production of resting 

 spores follows the septation and anastomosis of a mass of hyphae filling the host, the 

 spores being produced laterally from these hyphae without regard to the points of an- 

 astomosis. In my own experience I have observed something of this sort in the legs 

 of insects attacked by E. sphaerosperma and its near ally E. occidenialis ; but in the 

 bodies of the hosts examined, which, it should be remarked, were of a very different na- 

 ture from those (Pleris larvae) studied by Brefeld, I found only short, contorted hyphae 

 producing spores apparently in a wholly asexual manner (fig. 217), but associated with 

 them, numerous instances where the budding spore was directly associated with a cross- 

 partition or a slight lip-like fold indicating the previous existence of such a partition 

 (figs. 211^216). Whether spores thus formed should be called zygospores seems at least 

 doubtful, and the partitions described may indicate merely the ordinary division of the 

 hyphae. In a very few cases, however, I have, in these two species, seen a process as w r ell 

 marked as that represented in fig. 197, occurring in the legs of certain hosts where, as a 

 rule, the hyphae attain a considerable length. This certainly looks like true conjuga- 

 tion, and may lead us to cases where the presence of a sexual union is hardly to be ques- 

 tioned. The first instance of the latter class discovered among the Entomophthoreae 

 is that described by JSTowakowski 1 in his three new species, E. conica, E. ovispora and 

 E. curvispora. In this type we have hyphae, within or without the body of the host, 

 producing lateral outgrowths at opposite points of two different hyphae, which meet 



1 l. c, A. 



