INTRODUCTION 



and the germs of minute organisms have been found to exist every- 

 where. Schwann and Pasteur have been pioneers in this work, 

 and have shown that it is possible to hinder the development of the 

 lower organisms, in places where it is customary to find them, by 

 destroying all existing germs and at the same time preventing the 

 entrance of new ones. It is due to the results obtained by these men 

 in their investigations on spontaneous generation that we are now 

 able to preserve food in a scientific manner. The germs previously 

 existing in the substance to be conserved are destroyed by heat, while, 

 by a proper mode of sealing, the entrance of new germs is rendered 

 impossible, and the decomposition, which their presence wovdd occasion, 

 is accordingly prevented. 



All known living organisms have been derived from other living 

 organisms. But the idea of the origin of living from dead substances 

 on the other hand derives important su^iport from the progress of 

 chemical research. In the early decades of the last century it was 

 customary to draw a distinct line of separation between organic and 

 inorganic chemistry, and to assume that the substances dealt with by 

 organic chemistry could only be produced by the vital action of 

 organisms. The laws governing inorganic chemistry appeared to have 

 no reference to organic chemistry, the formation of organic substance 

 being due to a special force, the "vital force." In 1828 WOhler 

 obtained urea from ammonium cyanate, and thus for the first time 

 produced an organic compound from an inorganic substance. In 

 1845 KoLBE completely synthesised trichloracetic acid, and in 1850 

 Berthelot synthesised alcohol and formic acid. The former substance 

 had been synthetically prepared by Hennel in 1828, but Berthelot 

 was the first to recognise its identity w^ith the substance formed in 

 alcoholic fermentation. By these results the former distinction between 

 organic and inorganic chemistry was destroyed. Organic chemistry 

 has become the chemistry of carbon compounds. Recently Emil 

 Fischer has synthesised sugars, and attacked the problem of the 

 synthesis of albuminous substances. 



In some such way it is possible that living matter originated from 

 non-living at some period in the evolution of the earth when the 

 conditions for its formation existed. In order that the organic Avorld 

 should have developed from the first living matter, one of the original 

 properties of the latter must have been a capability of continued 

 existence among its surroundings. It must have been capable of 

 variation and of retaining the new characters appearing in this way, 

 of growth, i.e. the increase of itself at the cost of foreign substances, 

 and of reproduction, ie. multiplication by separation into a number of 

 parts. Some observers have recently described the origin of micro- 

 scopic structures, which behave similarly to living beings, in bouillon 

 and other organic culture media when exposed to the action of 

 radium ("). 



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