308 The Bevelopnent of Organisms \^3oivnli!^fcT&'^ 
filaments increase in size and length. Their substance is gradually 
formed into cells, from which are thrown off certain bodies, some of 
which, with others of analogous character but probably of a dif- 
ferent origin, finally and unmistakably take the infusorial form of 
life. The whole progress is an evolution of vitality. Exactly the 
same course is pursued in the changes which take place in a cream 
infusion, except that the organic so-called "oil-globule" is the 
starting-point in the phases of evolution. But if we reject the 
hypothesis of " spontaneous generation," or heterogeny, what other 
explanation of the phenomena can be given ? It cannot be said 
that the germs of the fungoid growth, or of the infusoria, are intro- 
duced with the air or the water used in the experiments.* The 
phenomena in question completely negative this idea. Nor can we 
suppose that the germs of all the products are contained in the 
infusion itself. There is, certainly, a starting-point to which all 
may be traced — the contents of the cork cell in the one case, and the 
cream-globule in the other — but this accounts for the appearance of 
the first step only in the series of changes. Driven thus to a 
corner, the only conclusion we can draw is that the first germ 
is alone necessary. Given the cell-contents or the cream-globule, 
all the rest of the phenomena, whether they relate to animal or 
vegetable life, must inevitably follow, when the proper conditions of 
development are supplied. 
In support of this view, I will now detail other experiments I 
have made, first, however, referring again to the fungus of the cork 
infusion. This we have seen was developed, apparently, not from 
the material of the cell walls, but from the cell-contents. Not that 
the cell necessarily loses its vitahty immediately it becomes what 
Professor Beale terms " formed material." In the experiments above 
detailed, the cells give forth certain vital products in the course of 
the development of the fungus quite independent of the germs from 
which the infusorial life is evolved. It may be that these products 
themselves again combine immediately to form a vegetable structure, 
as I have seen several of them united endwise, and some at least 
of the milk-fibres had every appearance of being composed of cells 
thus joined and amalgamated. The cell -contents, however, are 
clearly the starting-point of the phenomena under review, judging 
from other phenomena to be now mentioned. 
In France, M. Bechamp t has made experiments which establish 
" the natural development of bacteria in the protoplasmic parts of 
various plants," and he affirms that this arises from the fact that 
the microzi/mse, or molecular granulations of the plant-tissue, are 
the germs of the bacteria. This opinion I have confirmed by the 
following experiments : — If a thin section of the tissue of a plant, 
♦ We must dissent from this proposition of the author's. — Ed. M. M. J. 
t See ' Popular Science Review ' for April, 1869. 
