i8yi.] The Theory of Atmospheric Germs. 159 



It was long ago ascertained that other fungoid spores 

 than those peculiar to yeast could, in a manner precisely 

 similar to the latter, induce fermentation. 



Penicillium cultivated upon lemon gave rise to alcoholic 

 fermentation, with the production of yeast globules, and, 

 conversely, yeast globules were found to produce Penicillium 

 as well as Mycoderma. It is obvious that this observation of 

 the mutability of species in fungoid organisms is of the 

 highest importance. The apparent structural characters of 

 the spores and the subsequent developments and fructifica- 

 tion of Mycoderma cerevisice differ widely from those of Peni- 

 cillium. If they are thus mutually convertible, it would 

 annihilate the argument advanced against the existence 

 of atmospheric germs on the score that, to explain the 

 different varieties of forms produced, one must concede the 

 existence of an immense number of germs in the air of 

 different kinds. This would tend to show, on the contrary, 

 that the same germ under different conditions could assume 

 the appearances and the functions of a different organism. 



The most elaborate investigation of recent date bearing 

 upon this subject has been made by Professor Hallier, of 

 Jena. 



According to Hallier, the same germinal molecules 

 develop according to the nature of the fermentescible sub- 

 stances in which they are deposited into the fungoid forms 

 peculiar to each fermentation. The forms inducing putre- 

 faction, fermentation, and mildew are all varieties of one 

 another. As they develop within fluids they are cellular, 

 formations. When they grow upon the surface only 

 do they present fructification (Schimmel). Hallier endorses 

 Pasteur's view that the germs of all are carried by the 

 air. The most abundant source of germs appears to be Peni- 

 cillium crustaceum (see fig. 2), whose spores are universally 



Fig. 2. Fig. 3. 



^ 



fit, 





°°°Q Vq'JOJ °o^o 



Aft 



r.V 







ructificatior 



1 of Penicillium 



Spores 



of Penicillium crustaceum bursting 



crustaceum 



. (Hallier.) 



in water 



and setting free their contained 







particles, 



which unite in rows or chains. 







(Hallier.) 





spread because it is more hardy, more fertile, develops 

 at lower temperatures, and grows and fructifies more 

 rapidly than others of its kind. It will accomplish its 

 growth and will bear fruit in forty-eight hours. A so- 



