360 TEXT-BOOK OF BACTERIOLOGY. 



only the columella hangs frequently for some length of time like 

 an empty, overturned cap over the hypha. 



The end of the hypha (likewise one-celled) of the aspergillia 

 swells in the shape of a club (like the head of asparagus) and is 

 then covered by a great many sterigma, flask-shaped, small struc- 

 tures with spores arranged like chains. The straight, articulated 

 hyphae of the penicillia divide, by tree-shaped, forked division in 

 their upper third, into compact tufts of short and erect pedicles, 

 called basidia, on which the spores lie in long rows. 



Nearly related to these genuine mould fungi are a number of the 

 lowest plants (the best known species is the oidium) which are more 

 simply organized, both in form and structure, and form, as it were, 

 the transition to the yeast fungi. The hyphae are but little devel- 

 oped, destitute of particular fruit-heads which are even sometimes 

 absent, so that the conidia articulate directly with the mycelium. 



The real " sprouting " or yeast fungi do not, as a rule, develop true 

 mycelial filaments. They are rather single, oval cells without chlo- 

 rophyl, with a thin membrane and a granular protoplasm inter- 

 spersed with vacuoles. The spores are developed within the proto- 

 plasm; they are large, irregular, roundish bodies inclosed in a 

 membrane and set free by the dissolution of the mother-cell mem- 

 brane. 



The " sprouting " (yeast) fungi multiply (as indicated by their 

 name) by sprouting. At one or more points, on the surface of a 

 cell, there arise small, bud or button-shaped protuberances gradu- 

 ally increasing in size and circumference, and finally separated from 

 the mother cell by a constriction. But they frequently remain con- 

 nected with the latter, and as the same process is usually repeated 

 in every newly-formed member, long rows of these yeast cells are 

 joined into extensive combinations of yeast fungi. 



The yeast fungi (saccharomyces) reveal their affinity with the 

 higher fungi by peculiar deviations from the common phenomena 

 of growth. A distinct tendency to produce mycelium is some- 

 times noticed, especially on solid media; the members dwindle 

 away to short, somewhat irregular hyphae. 



The ways and means of preparing these micro-organisms for 

 investigation essentially agree with those used for bacteria; but a 

 few differences must be noted. 



The mould fungi generally resist the common staining sub- 

 stances, the species of aspergillus being the most accessible. But 

 Loffler's methyl-blue will always bring to light the mycelium and 

 hyphae, and sometimes even the spores whose membrane does not 

 seem to be as thick as that of the bacteria. 



