236 



INTRODUCTION TO THE STUDY OF FUNGI 



failing to reach a suitable host, a secondary conidium is formed, 

 resembling that from whence it was derived (Fig. 112). 

 Should this second fail in finding a suitable host, a third is 

 formed from the second in the same manner. 



The other form of reproduction is by means of resting 

 spores, which may be sexual or 

 asexual, and proceeds also from the 

 hyphal bodies. The latter, or 

 azygospores, are formed by the 

 conversion of a hyphal body into a 

 resting spore, or by direct budding 

 therefrom (Fig. 113). They are 

 usually spherical, rather large, sur- 

 rounded by triple walls. Sexual 

 resting spores, or zygospores, are 

 produced as the result of conjuga- 

 tion of opposite threads. Threads 

 either within or without the body 

 of the host produce lateral out- 

 growths, at opposite points of two 

 different threads, which meet mid- 

 way and coalesce. The intermediate 

 walls are absorbed, a connective is 

 formed, and the contents are mingled. A bud is produced upon 

 the connecting canal, which appropriates 

 the contents of the two conjugating 

 cells, and the zygospore is formed. 

 After this the empty hyphae disappear. 

 Earely another modification of conjuga- 

 tion takes place. The hyphal bodies 

 join laterally, by means of short pro- 

 cesses, and produce an expansion at the 

 point of union, which enlarges and 

 absorbs the contents of the two con- 

 jugating bodies, and thus a resting spore, 

 or zygospore, results. Some other slight 

 modifications take place, according to 

 the species, but the general character is 

 the same (Fig. 114). The mature resting spores are spherical, 



PlQ. 112. — Secondary spores of 

 Entomophthom. S.P.C.K. 



Fig. 113. — Conjugating 

 hyphal bodies. Thaxter. 



