HEAT UPON LIVING MATTER. 155 
wise than by ‘spontaneous generation,’ Spallanzani 
was compelled to assume (2) that the unknown germs 
whose existence had been postulated, notwithstanding 
their animal origin, were of the nature of seeds rather 
than eggs, because they were capable of undergoing 
desiccation with impunity—such ability to survive 
desiccation conferring upon them the greater power 
of resisting heat which characterizes seeds. Nay, 
further (4), although no seeds could be shown to be 
able to resist the influence of boiling water, Spallan- 
zani assumed that these unknown seed-like germs 
might be able to do so.* Thus alone was he able to 
continue in the Panspermatist faith—on the strength , 
of these hazardous assumptions only, could he refuse 
assent to the probability of a germless origin of living 
matter, more or less after the fashion suggested by 
Needham and others. 
We may, therefore, now consider how far «the pro- 
gress of science has tended to confirm or reverse the 
hypothesis by which Spallanzani sought to shelter 
* He had only met with a few seeds which had resisted a momentary 
exposure in dry sand to a temperature of 212° F. But seeing that not 
one of the numerous seeds with which he had experimented had been 
able to survive a similar momentary exposure to boiling water, he had 
no real warrant for supposing that the germs in question would be able 
todoso. Spallanzani, in short, here committed the error of arguing that 
what had occurred in dry sand might occur in water—even though 
his own experience had not supplied him with a single instance of 
survival of egg or seed after it had been even momentarily scathed by 
boiling water. 
