102 PHYSIOLOGY OF THE BACTERIA. 



Heterogenesis. — Since the experiments of Pou- 

 chet and of his pupils, and the arguments given 

 by MM. Tre'cul and Fremy, the last facts invoked 

 in favor of heterogenesis are due to MM. Onimus, 

 Servel, Bastian, etc. 



M. Onimus contends that the " proto-organisms 

 may be born in media, protected against the air, 

 which contain albuminoid substances." 



M. Martin sustains an analogous idea. Accord- 

 ing to him, the bacteria are derived from protein 

 granules. According to Neusch, bacteria are pro- 

 duced in the interior of animal or vegetable cells 

 without any lesion and without coming from the 

 air. To demonstrate this he plunges divers fruits 

 under water, in saline or acid liquids (phosphates, 

 sulphates, carbonate of potassa, etc.), and he finds 

 there bacteria; but, according to him, these are 

 not living organisms, properly so called, but ab- 

 normal cellular vegetations. 



M. Servel, decapitating some guinea-pigs, caused 

 the heads, the livers, and the kidneys to fall into 

 a solution of chromic acid, 1 to 100. At the end 

 of several days, the superficial parts were hard : 

 ened ; but the centre was softened, and filled with 

 bacteria. 



The presence of bacteria in eggs has several 

 times been verified, and the heterogenists have 

 hastened to draw an argument from this fact in 

 favor of their theory. M. Gayon explains the ap- 

 pearance of these organisms in the eggs of birds 

 by their presence in the normal state in the 

 oviducts. 



