MEMORANDA. 145 
them perfectly exact, sisted on the necessity of following 
with absolute accuracy the directions given by M. Pasteur, 
directions which cannot be deviated from with impunity. 
M. Regnault entirely supported M. H. Sainte-Claire De- 
ville’s remark ; he had seen in his countless experiments on 
the expansion of gas how, even in working with the mercury 
trough, it was difficult entirely to prevent the introduction of 
extraneous air; the laisser aller with which M. Pouchet had 
carried out his first experiments had greatly astonished him. 
M. Pasteur reminded the Academy that he had formerly 
stated that the mercury trough was a receptacle of a multitude 
of germs which it caused to enter into all the bottles and 
tubes manipulated in it. . 
M. Milne-Edwards begged that an important experiment 
which he had previously referred to might not be forgotten. 
A small capsule containing germs derived from the atmosphere 
was floated on the surface of a liquid peculiarly susceptible of 
putrescence, and the liquid, even after many days, remained 
completely limpid and unaltered; afterwards, on overturning 
the capsule, the liquid became impregnated in some way or 
other, and at the end of a few days it was seen to be filled 
with a multitude of organized products. 
M. Pasteur and other members took this opportunity of 
calling attention to the simpler and more decisive experiment 
-—a real experimentum crucis—which consists in putting 
side by side two flask with necks drawn out to a point, and 
containing the same fermentable liquid, the open and slender 
neck of the one flasks remaining straight and vertical, whilst 
the slender and open neck of the other flask remained bent, 
with the opening downwards. ‘The liquid of the first vessel 
was soon invaded by microscopic vegetation, although often, 
at least, the liquid of the second vessel remained entirely 
unaltered. 
M. Pasteur had attended the meeting of the Academy for 
the purpose of exhibiting two flasks which he had filled with 
air on the Mer de Glace, without the contents having been in 
any way affected. After the meeting he met his colleague, 
M. Frémy, in the library, and the latter asked him what 
would happen if the neck of the vessel were broken. M. 
Pasteur did not hesitate to reply, that Mucedinee,would soon 
make their appearance. The neck of one of the flasks was 
accordingly broken, and the flask itself placed in a corner of 
the library. When M. Frémy and M. Pasteur returned 
eight hours later, the liquid, previously so clear, had lost its 
transparency, numerous living organisms were visible, and 
there was already a thin deposit of dead ones—thus brilliantly 
confirming the results of M. Pasteur’s experiments. 
