136 YEAST 



IV 



plasm, cellulose, and fatty matters, in any quantity, 

 although they are wholly deprived of those rays of 

 the sun, the influence of which is essential to the 

 growth of ordinary plants. There has been a 

 great deal of speculation lately, as to how the 

 living organisms buried beneath two or three 

 thousand fathoms of water, and therefore in all 

 probability almost deprived of light, live. If any 

 of them possess the same powers as yeast (and 

 the same capacity for living without light is ex- 

 hibited by some other fungi) there would seem to 

 be no difficulty about the matter. 



Of the pathological bearings of the study of 

 yeast, and other such organisms, I have spoken 

 elsewhere. It is certain that, in some animals, 

 devastating epidemics are caused by fungi of low 

 order similar to those of which Torula is a sort 

 of offshoot. It is certain that such diseases are 

 propagated by contagion and infection, in just 

 the same way as ordinary contagious and infectious 

 diseases are propagated. Of course, it does not 

 follow from this, that all contagious and infectious 

 diseases are caused by organisms of as definite 

 and independent a character as the Torula ; but, 

 I think, it does follow that it is prudent and wise 

 to satisfy one's self in each particular case, that the 

 "germ theory" cannot and will not explain the 

 facts, before having recourse to l^potheses which 

 have no equal support from analog} 7 . 



