186 
PROFESSOR TYNDALL ON THE DEPORTMENT AND VITAL 
been the product of external germs. Through profound and thorough hardening and 
desiccation, through defect of contact with the liquid or some other cause, some germs 
in the infusion itself had, I doubt not, been enabled to withstand the extraordinary ordeal 
here described. 
Was it “the blighting influence of heat” that deprived these 8-hour bulbs of the 
power of spontaneous generation 1 Whatever be the meaning attached to such 
language the reply is obvious, that the “ blighting ” was the same for all the bulbs ; and 
yet we find one of them, which, when taken from the boiling water, was perfectly 
brilliant, rendered in two days muddy with organisms. Further, it was only necessary 
to wash with perfectly sterilized distilled water the adherent germs from a small bunch 
of hay, and to inoculate the clear infusion in an 8-hour bulb with the washing-water, to 
cause it within four and twenty hours to become turbid throughout. To speak more 
definitely, 14 hours in the warm room were found sufficient to cloud the infected 8-hour 
bulb with Bacteria. Thus the infusion, when living germs are restored to it, shows its 
perfect competence to develop them, and it was solely the destruction of the germs which 
it possessed before it was boiled that rendered it sterile afterwards. 
It is worth bearing in mind that the particular kinds of hay whose germs manifested 
these extraordinary powers of resistance were so sapless and indurated that the specific 
gravity of their infusions, even after five hours’ digesting, could not without difficulty be 
sensibly raised above that of distilled water. This was more especially the case with old 
Heathfield and old Colchester hay, the infusions of which, though highly coloured, were 
marked, almost without exception, “ specific gravity 1000.” Old London hay-infusion 
was usually 1003, while infusions of new Heathfield hay were raised without difficulty 
to 1007*. 
As already stated, I never felt safe in these experiments until they were checked by 
careful repetition. A partial corroboration has been already adverted to. But on the 
2nd of March I had the same infusions prepared, kept in a cool place throughout the 
night, and introduced into four groups of bulbs next morning. The infusions were all 
brilliant. During the process of boiling one group of bulbs blew up, hence one link is 
absent from the series. I thought the 4-hour group could be best spared, and therefore 
selected it for omission. We had thus the infusions subjected for one, two, three, five, and 
six hours respectively to the boiling temperature. The three first hours agree exactly 
with their predecessors. No single bulb within these limits was sterilized, all of them 
became turbid throughout and loaded with scum. One bulb of the 5-hour group and 
one of the 6-hour group also became turbid and flocculent within, but without any scum 
upon the surface. As in the case of the 8-hour bulb already mentioned, this appearance 
* A comparative experiment on dried and undried peas, described in the ‘ Proceedings ’ of the Royal Society 
(1877, vol. xxv. p. 503), may be referred to here as illustrating the manner in which desiccation restricts diffusion, 
and thus tends to preserve the integrity of the desiccated germ. I suppose the original mineral salts of the hay 
were still retained in the old samples ; but hot water appeared to have little power of extracting them. The 
resistance of the hay in this respect appeared to be shared by its germs. 
