102 PHYSIOLOGY OF THE BACTERIA. 
Heterogenesis. — Since the experiments of Pou- 
chet and of his pupils, and the arguments given 
by MM. Trécul and Frémy, the last facts invoked 
in favor of heterogenesis are due to MM. Onimus, 
Servel, Bastian, ete. 
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. 
