ML CO RALES 25 



the plant, and they retain their germinating power for a long 

 time. Sexual reproduction takes place by the advance of two 

 short hyphal branches toward each other which unite and fuse 

 after each has formed a special reproductive cell. As a result of 

 this union, a zygospore with a thick protective covering is borne 

 on the united hyphae which are then known as suspensors. (PL 

 2,f. 2,3, 4.) 



Another common mould growing mostly on horse dung (PL 2, 

 f. 8, p) illustrates a different type of growth. The creeping my- 

 celium sends up slender crystalline columns each of which forms a 

 single urn-shaped body at the summit ending in a globular or 

 lens-shaped black sporangium. By the accumulation and ulti- 

 mate compression of the gases of decomposition in this urn, the 

 sporangium is shot upwards with considerable force and with a 

 slight report. By holding the hand palm downward over a mass 

 of these mature moulds, the discharge can be distinctly felt and the 

 sporangia are sometimes propelled to the distance of several feet. 

 This fungus is known as Pilobolus crystallimis. 



Other genera can be found growing on moulds which have 

 been for some time under cultivation, Chaetocladiuui Jonesii is 

 one of the common species and Piptocephalis Friesii (PL 2, f. 

 5, 6, 7) is another frequently found. 



In some genera the sporangium becomes reduced in size and 

 its contents instead of dividing to form numerous spores, remains 

 entire and so have the appearance of simple conidium ; these 

 conidia-like sporangia are sometimes borne singly, sometimes in 

 clusters. In some genera the suspensors produce branches after 

 conjugation which form a sort of protective covering to the zygo- 

 spore. In most cases the sexual reproduction occurs on creeping 

 hyphae , in Sporodinia, a form comparatively common in summer 

 on the larger fleshy fungi (notably the Boleti}, the conjugation 

 occurs on aerial hyphae. 



The moulds can be easily developed on various kinds of media, 

 like dung of various sorts (fresh horse dung is the simplest and 

 most thoroughly productive), and form an exceedingly interesting 

 group for study. Much has yet to be learned of the development 

 of many of the species, and while many forms are known to occur 

 in America, only a few of our forms have been studied with any 

 degree of care. 



