ON THE VITALISTIC VIEW OF NATURE. 391 



of very valuable but unconnected researches in all the 

 different countries where chemistry was cultivated. 

 Priestley, in England, had noticed the purifying effect 

 of plants on air ; De Saussure, in a series of remarkable 

 experiments, carried on in the last years of the eighteenth 

 century at Geneva, established the fact that in sunlight 

 plants increase the quantity of carbon and other con- 

 stituents in their tissues. Ingenhousz in Holland and 

 Senebier in France had shown that in the presence of 

 sunlight bubbles of oxygen gas are given off by plants 

 when plunged under water, and had traced this oxygen 

 to its source, the carbonic acid in the atmosphere. Sir 

 Humphry Davy had applied chemistry to agriculture ; 

 and, much later, German physiologists like Tiedemann 

 and Johannes Miiller had recognised the necessity of 

 explaining the processes in the living body chemically. 

 All these labours, however, were detached, and their 

 value was little known. It was therefore a very timely 

 proposal which issued from the British Association in 

 1839, that a report on the present state of organic 

 chemistry should be drawn up. For this task no less 

 a person than Justus Liebig was selected. 1 The event 



1 The sources of information on | Liebig, his Life and Work." Bis- 



Liebig's great work in revolutionis- chofFs address contains a very full 



ing the science of life through his j discussion of Liebig's vitalistic sym- 



application of organic chemistry to ! pathies. His great influence was 



agriculture and physiology are nu- established as much by his special 



rnerous. In particular there are scientific discoveries as by his 



two addresses by Vogel and von j method of teaching, by his early 



Bischoff, delivered in the Munich [ attempts to popularise science and 



Academy in 1874, Hofmann's "Kara- make it an educational power 



day " lecture, delivered in the Royal i through his well-known ' Familiar 



Institution in 1875, and a very Letters." He was in this respect a 



able summary, drawn mainly from 

 these sources by Mr W. A. Shen- 

 stone, in Cassell's ' Century Science ' 

 Series (1895), entitled "Justus von 



pioneer, as after him Helmholtz arfd 

 Du Bois-Reymond were pioneers in 

 spreading scientific ideas by means 

 of popular lectures and addresses. 



