HEAT UPON LIVING MATTER.. 139 
deavour to make a sort of compromise, trying to 
retain some of their most deeply-rooted convictions 
and mix them harmoniously with new views. Me- 
tallic mercury, however, will not mix with water, and 
it will be found that there is a similar incompati- 
bility between the explanations of the Pansperma- 
tists and our present state of knowledge in regard to 
the question of the Origin of Life. 
It remains for me now, therefore, to. trace the 
different steps by which we have arrived at our 
present knowledge concerning the destructive effect 
of Heat upon Living Matter. And, to do this effec- 
tually, I must refer my readers to good work done in 
the latter third of the last century by the acute and 
learned Abbé Spallanzani, whilst he was engaged in 
promulgating Panspermatist doctrines in opposition 
to the views of our countryman Needham, who, in 
those days, steadfastly proclaimed the. truth and 
reality of ‘spontaneous. generation’—though the 
philosophical doctrines. by. which he was influenced 
caused him to limit the-acceptation of the phrase to 
what we now understand. by the term Heterogenesis. 
I refer first of all to the work of Spallanzani, partly 
because he alone, of all thase who have adopted 
Panspermatist views and. have. taken part in this 
controversy, has fairly and. fully faced the question 
