
50 THE EVOLUTION OF LIFE 
envelopes of some seeds which are only killed at a 
temperature near 212° are not harder than the shell 
of an egg, which is nevertheless killed at the much 
lower temperature of 140°. The actual difference 
is explicable principally, according to Spallanzani, 
rather by the fact that the fluids contained within 
the egg are so much more abundant than those 
oe The seed. 
Spallanzani’s argument thus naturally suggests 
the notion that many of the seeds with which he 
experimented required a high temperature to kill 
them, merely on account of their dryness. If the 
seeds had previously been well soaked in cold 
water, or better still in warm water, so as to have 
been thoroughly moistened, might they not have 
been killed at a much lower temperature—that is, 
only a little, if at all, over 140° F.—the temperature 
which proved destructive to the more moist animal 
germs ? 
It is well known, in fact, that seeds of plants 
provided with a thick and hard coat may—especially 
after prolonged periods of desiccation—germinate 
even after they have been boiled for a very long 
time in water. This was ascertained by Pouchet to 
be the case with an American species of Medicago. 
Some of the seeds were completely disorganised by 
the boiling water, while a few remained intact, and it 
was these latter which were afterwards found to 
germinate. They had been protected from the 
influence of the boiling water by their very dry and 
hardened coats. Facts of the same kind have been 
recorded by Professor Jeffries Wyman, who pointed 
