328 



Prof. H. C. Bastian on the Heat 



not enable us to decide whether the exciting cause of this delayed turbi- 

 dity is in part the living element whose vitality and rate of reproduction 

 has been lowered by the heat, or whether the effects are wholly attribu- 

 table to the mere organic matter of the inoculating compound. 



So far, therefore, we have concomitant variations which are equally 

 compatible with either hypothesis. But it will be found that each of the 

 three succeeding arguments speaks more and more plainly against the 

 possible influence of the living element, and in favour of the action of 

 the orgauic matter of the inoculating compound, as an efficient exciting 

 cause of the delayed putrefactions occurring in the cases in question. 



3. As stated in my last communication *, when single drops of slightly 

 turbid infusions of hay or turnip previously heated to 140° P. are mounted 

 and securely cemented as microscopical specimens, no increase of turbi- 

 dity takes place, although drops of similar infusions heated only to 

 122° P. do notably increase in turbidity (owing to the multiplication of 

 Bacteria) when mounted in a similar manner. Under such restrictive 

 conditions as these, in fact, a drop of an inoculated and previously heated 

 organic infusion behaves in precisely the same manner as a drop of a 

 similarly treated amnionic-tartrate solution. In each case, when heated 

 to 140° F., turbidity does not occur, apparently because there are no 

 living units to multiply, and because in these mere thin films of fluid 

 dead ferments are as incapable of operating upon the organic fluids as 

 they are upon the amnionic-tartrate solutions. 



4. Because, in the case of the inoculation of fluids which are not easily 

 amenable to the influence of dead ferments, such as a solution containing 

 amnionic tartrate and sodic phosphate, this delayed turbidity does not 

 occur at all. Such inoculated fluids become rapidly turbid when heated 

 to 131° F., though they remain clear after a brief exposure to a tempera- 

 tare of 140° F. When the living units in the inoculating compound are 

 killed, there is nothing left to induce turbidity in such solutions. The 

 mere fact that these fluids do not undergo change when exposed to the 

 air proves conclusively that they are vely slightly amenable to the in- 

 fluence of the ordinary dead organic particles and fragments with which 

 the atmosphere abounds. The absence of delayed turbidity in these 

 fluids serves, therefore, to throw much light upon the cause of its occur- 

 rence in the organic infusions. 



5. And, lastly, I can adduce crucial evidence supplied by the " Method 

 of Difference," speaking with its accustomed clearness. Two portions of 

 the same hay- or turnip-infusion can be inoculated in such a manner as 

 to supply us with the information we require. In the one case we may 

 employ a drop of a turbid amnionic-tartrate solution previously heated 

 to 140° P., in which, therefore, the living units would certainly be killed ; 

 whilst in the other we may add an unheated drop of the same turbid 

 saline solution to the organic fluid, and then heat this mixture also to 



* Loc. cit. p. 228. 



