EXPERIMENTS. 



47. 



The results of many experiments have, however, 

 been brought forward in favour of the doctrine of 

 heterogenesis. Organic matter, air, and water, which 

 have been subjected to various operations supposed 

 to effectually destroy any living particles that may be 

 present, have been introduced into glass vessels which 

 have afterwards been hermetically sealed. In spite of 

 every precaution germs have made their appearance, 

 and it has been inferred therefore that these sprang 

 into existence without being in any way indebted to 

 parental organisms. 



In 1864-65 I examined with Dr. Child the contents 

 of several hermetically sealed glass flasks, into which 

 various vegetable infusions had been introduced. In 

 order to prevent the entrance of germs from the air, 

 and to destroy any germs which might exist in a living 

 state in the matters introduced into the flasks, the 

 following precautions were adopted by Dr. Child. 

 (" Essays on Physiological Subjects," second edition, 

 page 1 1 6.) 



" In these experiments I have adopted some slight 

 modifications of the apparatus used in the former ones. 

 That now employed consists of a porcelain tube, the 

 central part of which is fitted with roughly pounded 

 porcelain ; one end is connected with a gas-holder, 

 and to the other the bulb is joined, which contains the 

 substance to be experimented upon. The bulb has 

 two narrow necks or tubes, each of which is drawn out 

 before the experiment begins, so as to be easily sealed 



