THERMAL DEATH-POINT OF LIVING MATTER. 699 



Jean Seneljier, " Opuscules de Physique, Animale et Vegetale^'' the 

 translation itself having been published at Geneva in 1767. 



Reflecting upon the import of the experiments of his own that he 

 had just recorded, in which living organisms were found in closed ves- 

 sels containing infusions of certain vegetable seeds after these closed 

 vessels had been immersed in boiling water for half, or, in some cases, 

 nearly three-quarters of an hour, Spallanzani frankly avows (p. 48) 

 that if the first of the new organisms had not come into being by some 

 such independent method as that suggested by Xeedham, they must 

 have appeared either because certain " germs " from which they had 

 been derived had been able to resist the destructive influence of boil- 

 ing water for nearly three-quarters of an hour, or because, after the 

 cooling of the closed vessels, some of the organisms observed had 

 passed from the air through certain imaginary pores of the glass. At 

 the first glance these seemed, as he says, " deux suppositions egalement 

 impossibles, ou du moins tres difficiles a concevoir." For very excel- 

 lent reasons, not difficult for the reader to imagine, the abbe then 

 points out that the latter hypothesis, at all events, is entirely untenable. 

 The question thus became one of the simplest description. If no good 

 reason could be found in support of the seemingly improbable supposi- 

 tion that the experimental results referred to were to be accounted for 

 by a survival of germs, then, as he confessed, he must admit the fact 

 of an independent and germless origin of living things. If, on the 

 other hand, it should appear probable that germs or reproductive par- 

 ticles of living things could survive the influence of such a prolonged 

 immersion in boiling fluids, he would not feel at all bound on the 

 strength of his previous experiments to believe in the independent 

 origin of living matter. This simple issue was fully realized by Spal- 

 lanzani, and, acting in accordance w^th the most obvious of scientific 

 principles, he carefully sought for fresh evidence by means of well- 

 directed experiments, in order to guide him toward a conclusion as to 

 whether germs of living things could or could not have resisted the 

 action of boiling water for more than half an hour. 



He approached the question in the following manner : " Can one," 

 he says, " find any proof sufficient to banish, or, at all events, to dimin- 

 ish one's natural repugnance to admit that the germs of animalcules 

 of the lowest order have the power of resisting the action of boiling 

 water ? In reasoning from the germs or eggs of animals with which 

 we are acquainted, would it be difficult for us to imagine animalcules 

 having this peculiarity ? It is true that we are not acquainted with 

 any eggs endowed with such properties. I have already considered 

 this subject in the ninth chapter of my Dissertation. I there show 

 how several kinds of eggs of insects — not to speak of eggs of birds — 

 perish under a heat less than that of boiling water. I have shown also 

 that the seeds of plants are destroyed when they are exposed to the 

 heat of boiling water, and that even those whose outer coat is of the 



