700 THE POPULAR SCIENCE MONTHLY. 



hardest description are not thereby spared." But he goes on to say, 

 as he had only been able hitherto to make his observations on a limited 

 number of eggs and seeds, there was the chance that more extended 

 observations might reveal some capable of resisting this generally de- 

 structive influence. He says he had never lost this hope, with regard 

 to seeds more especially, since he had seen a statement byDuhamel to 

 the effect that some grains of wheat had germinated after having been 

 heated in a stove to a temperature above the boiling-point of water/ 

 And as there is a considerable resemblance between seeds and eggs, 

 Spallanzani was led to hope that something of the same alleged extraor- 

 dinary capacity for resisting heat might be possessed by the eggs or 

 germs of such organisms as make their appearance in previously boiled 

 fluids. He was therefore stimulated to undertake fresh observations 

 upon eggs and seeds generally, with the view, on the one hand, of 

 ascertaining the precise temperature which proved fatal to each kind, 

 and, on the other, of finding out whether these eggs or seeds were 

 capable of resisting a greater degree of heat than the several animals 

 or plants to which they belonged. 



This latter part of the inquiry was rightly deemed by Spallanzani 

 to be of great importance and capable of affording him much guidance 

 toward the proper interpretation of his other experiments. He had 

 already determined that the lower infusoria themselves are killed at a 

 temperature of 34° Reaumur, or 108|^° Fahr. ; and now having found 

 that such organisms would appear within closed vessels previously sub- 

 jected to a temperature of 212° Fahr., owing, as he was inclined to think, 

 to a survival of their germs, Spallanzani was anxious to ascertain 

 whether he could gain sufficient support for this hypothesis — that is, 

 whether the difference in the capacity of resisting heat, imagined to 

 exist in this case between parents and germs, could be justified by the 

 establishment of similar differences in heat-resisting capacity between 

 other parent organisms and their germs. 



In carrying out these inquiries, Spallanzani adopted the follow- 

 ing method (p. 53) : He placed the eggs, seeds, or organisms, in a ves- 

 sel containing cold water, into the upper strata of which was im- 

 mersed the bulb of a thermometer. The water was then heated slowly, 

 and when the thermometer indicated that the temperature had been 

 attained, whose effect it was desired to test, the eggs, seeds, or organ- 

 isms, were at once withdrawn and placed, under suitable conditions, in 

 a separate vessel. The effects of different grades of heat vc^ow the 



^ Heated in all probability in the dry state. But it is well known that seeds and de- 

 siccated animals can resist the influence of heat much better in the dried state than when 

 they are thoroughly moistened and then heated, and it is as to the effects of heat upon 

 living matter under the latter conditions with which we are at present concerned. For 

 this reason, therefore, I shall not dwell upon those experiments of Spallanzani, in which he 

 heated seeds in the midst of dry sand — these experiments lie outside the boundaries of 

 our present inquiry. 



