ENTOMOPHTHORALES 



295 



oped asexually (Fig. 108). The spore formed in the latter case is 

 morphologically equivalent to the zygospore, and is termed the 

 azygospore. The true zygospore is formed when two hyphal 

 bodies or two mycelial cells conjugate. The young zygospore 

 arises as an outgrowth from one of the conjugating cells, or may 



Fig. 108. — Empusa spp. (a-c) Zygospore formation between cells of hyphae 

 in three different species, (d) Three stages in zygospore formation, (e) Echinu- 

 late zygospore typical of one species, (y, h) Terminal and intercalary azygo- 

 spores. (m) Successive steps in conjugation of hyphal bodies to form zygospores. 

 (After Thaxtcr 1888.) 



bud out from their point of union as in Piptocephalis. At 

 maturity it is usually large and spherical, and may be character- 

 istically roughened. The fusing cells are plurinucleate. Though 

 fusion of the nuclei in pairs at the time of zygospore germination 

 was suspected by Riddle (1906: 184), it has not yet been demon- 

 strated. In azygospore formation a bud is put out from a hyphal 

 body or mycelial cell, and enlarges to form a spore similar to the 



