of Bacteria and their Allies by Heterogenesis. 397 
prolonged search has made their presence abundantly clear, 
and has shown that the “ spontaneous ”’ changes occurring in 
so many distinct foci in the very midst of their tissue has 
been correlated with the origin and development of micro- 
organisms. 
I have also made a very few observations on Tangerine 
Oranges, to two of which I will refer. In February, 1901, 
two of these oranges were placed in a screw-top bottle and 
soaked in a 10 per cent. solution of formalin for fifteen 
minutes, the fluid being also shaken about several times so as 
to wet the whole inner surface of the bottle. After the fluid 
was poured off and the cover tightly screwed on, the bottle 
was placed in a cupboard for fifteen days, the average tem- 
perature of which was about 50° F. 
When the first of these oranges was cut through in a 
longitudinal direction, a slight mouldy odour was at once 
perceived, and in the central white tissue and around the 
pips there was a greenish-black mass of mould. This was 
strictly confined to the central parts of the orange, and 
nowhere came within three fourths of an inch of the surface. 
The skin generally was perfectly sound, though it had become 
hard and was of a slightly brownish colour from the action 
of the formalin. Microscopical examination of the more 
peripheral parts of the orange also showed no mycelial 
filaments or organisms of any kind. 
The other orange in the same bottle showed no organisms 
either to the naked eye or on microscopical examination. 
Soon afterwards two other Tangerine oranges were treated 
in the same way, and subjected to similar conditions, except 
that they were left in the bottle for a much longer period— 
that is, for five and a half weeks instead of only fifteen days. 
About five days before the bottle was opened, one of the 
oranges was seen to show a patch of dark colour on one side, 
and when it was subsequently cut open longitudinally all 
the central white tissue was found to present an altered 
appearance, being of a rather dirty white colour; and on 
microscopical examination it was found to be densely infil- 
trated with a delicate Fungus mycelium. The seeds were 
discoloured, and the mycelium was also found to extend into 
the yellow substance of the orange. In one place there was a 
patch of a blackish colour, and this was found to have grown 
into the rind of the orange at the point where tle discolora- 
tion on the surface was seen, It had not, however, actually 
reached the external surface ; it had evidently grown from 
