698 THE POPULAR SCIENCE MONTHLY. 



a sort of compromise, trying lo retain some of their most deeply-rooted 

 convictions and mix them harmoniously with new views. Metallic 

 mercury, however, will not mix with water, and there is a similar in- 

 compatibility between the explanations of the panspermatists 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 diflferent steps by 

 which we have arrived at our present knowledge concerning the de- 

 structive effects of heat upon living matter. And to do this effectually 

 I must refer my readers to good work done in the latter third of the 

 last century by the acute and learned Abbe Spallanzani, while he was 

 engaged in promulgating panspermatist doctrines against the views 

 of our own countryman Needham, who, in those days, steadfastly pro- 

 claimed 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 those who have adopted panspermatist views and have 

 taken part in this controversy, has fairly and fully faced the question 

 of the degree of heat which proves fatal to various living things, by 

 making it the subject of direct investigation. Others who have since 

 defended similar views (including Pasteur in France, and Huxley and 

 Sanderson in this country) have not made the thermal death-point of 

 living matter a special subject of investigation, and have more or less 

 distinctly confounded the issues of this question with that of the cog- 

 nate though really distinct problem, as to whether certain infusions 

 could themselves prove mother-liquids, and give indej^endent birth to 

 living matter. Dire confusion has thus been produced. A problem 

 of a very simple nature has been made to appear very complex, while 

 those who are able clearly to understand the real nature of the ques- 

 tion at issue are left to marvel why the followers of Spallanzani have 

 never ventured frankly to deal with the question of the limits of vital 

 resistance to heat. Certainly they have displayed, to say the least, a 

 strange sluggishness in reference to this exceedingly important prob- 

 lem. But apart from the fact that no panspermatist, or declared op- 

 ponent of spontaneous generation, since the time of Spallanzani, has 

 fully and directly experimented upon this subject, I am all the more 

 induced to call the reader's attention to the abbe's treatment of it be- 

 cause, with some few exceptions, his investigations were conducted in 

 a manner which cannot be improved upon at the present day, and be- 

 cause his reasonings upon the subject are characterized by great sa- 

 gacity and fairness — allowance being made for the actual state of 

 knowledge in his time. The work of the learned abbe to which I shall 

 especially refer is entitled, in the admirable French translation by 



