git se ereiderel sim PROCEEDINGS OF SOCIETIES. 327 
First, with regard to the microscopic evidence, it consists in the 
assertion that some observers have seen organic living cells and fungus 
spores built up by the aggregation of minute granules. Now, there is 
very strong evidence on the other hand that this does not happen; the 
organisms described as fungus spores are in some cases not fungus 
spores at all, and in other cases they have been observed with a hilum 
or point at which they were attached to a parent. Surely, gentlemen, 
we cannot believe this point of attachment was the character of a spore 
formed de novo. 
On the other hand, I should be sorry to deny, with my present 
knowledge, that it is possible organisms of a simpler kind, such as 
unicellular organisms, may be built up in this way. If such a mode 
of evolution does take place, I still believe it is from pre-existing 
germs; such gemmules, for instance, as Mr. Darwin believes in, in 
his beautiful provisional hypothesis of pangenesis.* I believe, if it 
can be proved that organisms can be produced by aggregation, it will 
be found that this only takes place when pre-existing cells have given 
up their contents in the fluid experimented on. 
With regard to the experimental evidence, it has been arrived at 
from two classes of experiments. 
The first aims at the production of known organic forms from 
solution of animal or vegetable matter, the second aims at the pro- 
duction of new and unknown forms under new conditions in saline 
solutions. 
I shall consider these two sets of experiments separately. 
In the first, or simplest set of experiments, the most contradictory 
evidence has been arrived at by different observers. The whole, to my 
mind, may, however, be summed up in the following. 
If we receive the usually accepted belief that the boiling tempera- 
ture destroys germs, we must accept spontaneous generation as a fact. 
Tf, on the other hand, we believe that germs are not killed in this 
manner, these experiments only show that if the greatest possible care 
is used, germs may not be admitted and a negative result may be 
arrived at, and yet that germs may find their way into the flasks of the 
most careful experimenter, and may afterwards germinate. 
Now, gentlemen, I have instituted a series of the most careful 
experiments, which have shown conclusively to my mind that germs 
are not destroyed by the boiling temperature. 
I took a neutral solution of acetate of ammonia and put into it a 
number of spores of the little mould known as Penicillium glaucum, and 
boiled them well. I then enclosed some of the boiled fluid and germs 
in capillary glass tubes, like those used for preserving vaccine lymph. 
I then carefully examined the tubes by scrutinizing them with the 
microscope for an hour each, and not a spore had germinated, not a 
mycelial filament existed in the tubes. I then put the tubes into a 
warm place by the stove, and in twenty-four hours numerous mycelial 
filaments of considerable length had protruded from many of the 
* Mr. Lowne spoke at some length in favour of this hypothesis, and read that 
portion of Dr. Hooker’s address to the British Association at Norwich, in 1868, 
upon the subject. 
