
FINAL DECISIVE EXPERIMENTS 285 
; the “growth and multiplication ” of already existing 
living things—as shown by their rapid increase in 
the simple ammonium tartrate solution in distilled 
water: in which at least seven different kinds of 
micro-organisms were found growing side by side.’ 
Other Conjfirmatory Evidence 
A related de novo production of similar organisms 
by Heterogenesis I have elsewhere proved to occur. 
That is, just as in the superheated tubes, where liv- 
ing Bacterize were previously non-existent, such units 
can be made to appear; so they can be made to 
appear within the substance of pre-existing living 
things that were previously germless : and there also 
they develop from particles so minute as to be pre- 
viously invisible. Reference may be made to two 
such cases—one occurring within the tissues of a 
vegetable, and the other within those of an animal. 
It was strongly held by Pasteur that the cells of 
healthy plants are germless, and this view is still 
generally regarded as true. Bacteriologists cannot 
obtain evidence of the existence of micro-organisms 
in cells taken from the centre of a healthy potato or 
turnip, and yet Bacteria can be caused to appear in 
these situations, although adequate precautions are 
taken against infection. The method I have adopted 
is as follows :— 
A small new potato is first well washed in water, 
then it is put into a screw-top bottle contain- 
ing a Io per cent. solution of formalin, and allowed 
" See Knowledge ana Scientific News, Aug. 1905, p. 200. 
