ERYSIPHE 01DIUM. 



137 



protuberance, and behaves like a thick- walled sclerotium, 

 and probably, like the perithecia, owes its origin to a sexual 

 act. On suitable cultivation an ascus-bearing fungus grows 

 out of this sclerotium, and the ordinary mycelium and fruc- 

 tification can again be got from the ascospores thus ob- 

 tained. 



Otherwise it is only the conidia fructification of penicil- 

 liuni which is observed. The fruit hyphse are segmented 

 and branched like a tree, and a whorl of upright branches 

 projects like a pencil from the uppermost cell, each 

 branch bearing either a chain 

 of spores or another whorl of 

 branches, terminating in spore- > 

 chains. Spores spherical, u 

 cellular. PenicilliumglaucwTi, 

 the most common mould fungus 

 (fig. 22), gives risetoaflocculent 

 mould growth, at first white, but 

 later bluish-green. It grows 

 on the most various nutritive 

 substrata ; it occurs everywhere, 

 and hence its spores very often 

 gain access to cultivations. It 

 does not seem to flourish at high 

 temperatures (38 40 C.). 

 The diameter of the spores is 

 0-0035 mm. ; that of the hyphse 

 varies according to the food be- 

 tween 0'004 and 0*00071 mm. 

 The very stunted forms are un- 

 branched, and bear only a single 

 chain of conidia; when the de- 

 velopment is most luxuriant 

 several fruit hyphoe become 

 united to form a thick stem 



. \ Fig. 22. Pemcillium glaucum. 



(coremium), at the upper end m? myce ii a i hypha with a fruit 

 of which they again separate hypha passing upwards, 

 and form chains of conidia, in the manner described 

 above. 



Penicillium spores may be injected into rabbits and other 



