166 Transactions of the Boyal Microscopical Society. 
heterogenists are more fortunate than the inventors of perpetual 
motion, in the lengthy attention they have received from scientific 
bodies. In the domain of mathematical sciences it is, he says, 
possible to demonstrate that certain propositions cannot be true, 
but natural sciences are less able to predict results. The mathe- 
matician may disdain to cast his eye upon an essay which has for 
its object squaring the circle, or perpetual motion ; but the ques- 
tion of spontaneous generation excites public opinion, because it is 
impossible in the actual state of science to prove a priori that no 
manifestation of life can take place by a jump without the previous 
existence of a similar life. 
When any observer announces that he has discovered the con- 
ditions capable of causing the spontaneous origin of life, he is sure 
of the prompt adhesion of the systematic supporters of his doc- 
trine, and of raising a doubt in the minds of others who have only 
acquired a superficial knowledge of the subject. This is the more 
the case when an author, like Dr. Bastian, occupies an important 
position, has literary and dialectic talent, and brings forward con- 
scientious researches. 
During twenty years he has worked at this question, M. Pas- 
teur says he has not been able to discover any life not preceded by 
a similar life. The consequences of such a discovery would be 
incalculable. Natural sciences in general, medicine and philo- 
sophy in particular, would receive an impulse of which no one 
could foresee the consequences, and if anyone succeeds in reaching 
such a result, he would welcome the happy investigator on his 
operations being proved. At present his attitude is one of defiance, 
as he has so often shown how readily able men make mistakes in 
this difficult art of experimentation, and what danger is connected 
with the interpretation of facts. 
Let us see, he exclaims, whether Dr. Bastian has known how 
to escape these two rocks. He then cites the title of Dr. Bastian's 
paper and his chief remarks, and adds that he hastens to declare 
that the experiments described would usually give the results that 
are stated, and that he need not have operated at a temperature of 
50'^ C, as at 25° or 30°, and even lower, boiled urine rendered 
alkaline by potash in a pure atmosphere becomes filled with 
bacteria and other organisms. If Tyndall, as Dr. Bastian says, 
thought this was not so, it must have been through forgetfulness. 
Dr. Bastian cannot be unaware that the experiments he has just 
communicated to the Academy, or at least experiments of the same 
kind, were made by me, and published in a memoir of 1862, entitled 
' On Organic Corpuscles which exist in the Atmosphere : an 
Examination of the Doctrine of Spontaneous Generation.' I 
demonstrated in this paper (pp. 58 and 66) that acid liquids which 
always become sterile by a few minutes' exposure to 100° C, are 
