AND THE CAUSES OF FERMENTATION. 121 
he had recourse to an “ensemencement des poussiéres 
qui existent en suspension dans lair,” becomes quite 
easy and legitimate without having recourse to the 
hypothesis of Panspermism.* Now, also, are we 
enabled to understand all the apparent inconsistencies 
of those experiments in which previously boiled fluids 
have been exposed to the ordinary air of different 
localities, and have then been resealed. If many 
specimens of these fluids remained unchanged, whilst 
others, after a few days, swarmed with Bacteria and 
Vibriones, we may now very safely attribute these 
previously puzzling results to the comparative absence 
or presence of organic fragments in the particular 
volumes of air which chanced to get into the flasks, 
and to the different nature of the fluids employed by 
different experimenters. 
Many of the fluids which habitually remain clear 
after a previous ebullition in flasks whose necks have 
been plugged with cotton-wool, many times bent, or 
hermetically sealed after the entry of calcined air, or 
when enclosed in vessels which are completely full 
(in Gruithuisen’s fashion), belong to this subclass, In 
* See the experiments before alluded to, which are recorded in 
chaps. iv. and v. of his Memcir. 
+ See M. Pasteur’s Memoir, chap. vii, and also Compt. Rend., 
Nov. 5, 1860. See also a record of other experiments made with the 
air of alpine regions by MM. Pouchet, Joly, and Musset, in Comgzt, 
Rend., Sept. 21, 1863. 
