124: 



THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



dred and five instances, not one of which shows 

 the least countenance to the doctrine of sponta- 

 neous generation." 



Similar results have been obtained in France 

 by M. Pasteur, and once more there seemed to 

 be some promise of a settlement of the difficulty, 

 when Dr. Bastian communicated to the French 

 Academy the results of further experiments, in j 

 which he had heated his potash to a temperature 

 above that prescribed by his opponents and for 

 a longer time, and, under these circumstances, he 

 always obtained a copious development of bac- 

 teria. 



Thus, then, the matter now stands with re- 

 gard to this particular experiment, and the ques- 

 tion seems to have become one of experimental 

 ability between the upholders of the two opposing 

 views. There are, however, certain facts recent- 

 ly brought forward by Prof. Tyndall, which throw 

 a very important light upon the possible cause 

 of such extraordinary discrepancies. 



It is a well-known fact that dried peas resist 

 the action of boiling water for a much longer 

 time than green peas — that, in fact, the latter 

 are reduced to a pulp in a space of time hardly 

 sufficient to soften the former. Prof. Tyndall ' 

 found that an infusion of old hay was much more 

 difficult to sterilize than one of fresh hay, and 

 that, while a few minutes' boiling sufficed to kill 

 all germs in the latter, those contained in hay 

 a year or two old resisted the action of heat for 

 a very long time. He naturally concluded from 

 this that the almost infinitely minute germs of 

 microphytes may, in just the same manner as 

 peas, become dried and hardened, and so able to 



oppose a long and obstinate resistance to the ac- 

 tion of heat. 



Assuming, then, as it seems one is bound to 

 do, that germs may and do undergo this exces- 

 sive induration, one is able to form some concep- 

 tion of the difficulty of sterilizing a fluid in which, 

 as is certainly the case in very many instances, 

 such veteran germs occur, and to appreciate the 

 ingenuity with which Prof. Tyndall has overcome 

 the difficulty. He finds ' that frequent applica- 

 tions of a low degree of heat, applied at inter-' 

 vals, have a far greater sterilizing effect than a 

 single application of a very high temperature. 



A given fluid may contain germs of ail ages. 

 If this fluid is boiled for a considerable period, all 

 those of recent formation will be killed at once, 

 while those of considerable age will only be just 

 sufficiently softened to enable them to germinate 

 subsequently. If, on the other hand, the fluid is 

 first heated for a short time — and a fraction of a 

 second is often sufficient — the recent germs will 

 be killed, and those a degree older so softened, 

 that, after a period of latency, they are ready to 

 germinate. Heat now applied for a short time 

 will kill these, and fit a third set for growth ; 

 and the same course may be adopted for succes- 

 sive crops, until even the hardest and driest germ 

 is killed. It was found that a fluid which was 

 not rendered barren by boiling for an hour was 

 completely sterilized by this process, although 

 never heated up to the boiling-point, and al- 

 though the whole time of heating did not amount 

 to five minutes ; and even the infusions which 

 had given Prof. Tyndall most trouble were, with- 

 out exception, rendered permanently barren. 



A MODEEN "SYMPOSIUM." 



THE INFLUENCE UPON MORALITY OF A DECLINE IN RELIGIOUS 



BELIEF. 



DR. WARP. — I agree with the Dean of St. 

 Paul's, that the wording of our question is 

 unfortunately ambiguous ; and I think that this 

 fact has made the discussion in several respects 

 less pointed and less otherwise interesting than 

 it might have been. 



For my present purpose, I understand the 



1 " Preliminary Note on the Development of Organ- 

 isms in Organic Infusions." — Proceedings of the Royal 

 Society, vol. xxv., No. 177. 



term " religious belief " as including essentially 

 belief in a personal God and in personal immor- 

 tality. Less than this is not worthy the name of 

 religious belief; and, on the other hand, I will 

 not refer to any other religious truths than these. 

 I am to inquire, therefore, what would be the in- 

 fluence on morality of a decline in these two be- 

 liefs. 



1 " On Heat as a Germicide when discontinuous!/ ap- 

 plied." Read before the Koyal Society in February. 



