OPINIONS ON GENERAL PHYSIOLOGY 159 
herself imitates her procedures in fecundation in 
another state of things, without having need of the 
union or of the products of any preéxistent organiza- 
tion.” 
He proceeds to observe that in the places where 
his aura vitalis, or subtle fluid, is very abundant, as 
in hot climates or in heated periods, and especially in 
humid places, life seems to originate and to multiply 
itself everywhere and with a singular rapidity. 
“Tn this high temperature the higher animals and 
mankind develop and mature more rapidly, and dis- 
eases run their courses more swiftly; while on the 
other hand these conditions are more favorable to 
the simpler forms of life, for the reason that in them 
the orgasm and irritability are entirely dependent on 
external influences, and all plants are in the same 
case, because heat, moisture, and light complete the 
conditions necessary to their existence. 
“Because heat is so advantageous to the simplest 
animals, let us examine whether there is not occasion 
for believing that it can itself form, with the con- 
course of favorable circumstances, the first germs of 
animal life. 
“ Nature necessarily forms generations, spontaneous 
or atrect, at the extremity of each organic kingdom or 
where the simplest organic bodies occur.” 
This proposition, he allows, is so far removed from 
the view generally held, that it will be for a long 
time, and perhaps always, regarded as one of the 
errors of the human mind. 
“T do not,” he adds, “ask any one to accord it the 
least confidence on my word alone. But as surely it 
will happen, sooner or later, that men on the one 
