390 



BACTERIOLOGY. 



The mucor group is characterized by the presence of 

 spherical sacs or sporangia on the ends of the vertical fruit 

 hyphae. The contents of these sacs are at first homogen- 

 eous but, eventually, differentiation into round or oval 

 spores results. When fully ripe the sac bursts and the 

 spores are set free. The end of the fruit hypha is enlarged 

 or club shaped and projects into the sporangium, forming 

 what is known as the columella (Eig. 56 a). When the spor- 

 angium bursts the membrane disappears or dissolves with 

 the exception of a small ring around the base of the colum- 

 ella. 



Fig. 56. Fruit-organs of moulds, after Lehmann. A. — Sporangium of mucor, hlled 

 witii spores, showing columella; B — Aspergillus with sterigmae and spores; C — Penicillium 

 with basidia and spores. 



The mucors also give rise to zygospores which result 

 by the union of the ends of two mycelial threads. The 

 mycelial thread up to the fruiting stage is unseptate, and 

 represents, therefore, a continuous tube. When grown 

 in liquids the thread character gives place to yeast-like 

 cells. 3 or 4 species of this group are capable of inducing 

 experimental pathogenic effects. In very rare instances 

 mucor mycoses have been met with in man. 



The aspergillus group has no sporangia but, instead, the 

 ends of the fruit-hyphee are enlarged or club-shaped, the 

 enlarged end, or columella, is covered with radially ar- 

 ranged, minute bottle-shaped bodies — the. intermediate 

 spore bearers or sterigmce — from which chains or rows of 

 spores extend outward. Additional fruit organs, perithecia 



