20 GENERAL PHYSIOLOGY 



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spontaneous generation of animalcules in putrid infusions ; they 

 snowed that these lowest of all living things develop only from 

 germs which are to be found everywhere in the air and the water, 

 and that even here Harvey's dictum " omne vivum ex ovo " admits 

 of no exception. 



England and France produced the most of these exact researches, 

 while in Germany the most prominent thinkers, such as Oken, were 

 swept on by the philosophy of nature with its powerful tendency 

 toward pure speculation in the fields of natural science. 



E. THE PERIOD OF JOHANNES MULLER 



Johannes Miiller 1 (1801-1858) is one of those monumental figures 

 that the history of every science brings forth but once. They 

 change the whole aspect of the field in which they work, and all 

 later growth is influenced by their labours. 



Like the other investigators of his time Miiller was a vitalist, 

 but his vitalism had an acceptable form. To him vital force was 

 something different from the forces of lifeless nature, but its ad- 

 ministration rigorously followed physico-chemical laws, so that his 

 whole endeavour was to explain vital phenomena mechanically. 

 In doing this he went over the whole field of vital activities uni- 

 formly, neglecting no part, and by his own investigations, which 

 were always original, he laid the foundations upon which we work 

 to-day. He always kept his attention directed towards the whole ; 

 he never undertook special investigations which would not help 

 him to solve some large general problem. His ingenuity and it 

 is this that is so much missed in the more recent physiology was 

 expressed in the manner in which he attacked problems. He did 

 not recognise one physiological method alone, but employed boldly 

 every mode of treatment that the problem of the moment demanded. 

 Physical, chemical, anatomical, zoological, microscopic and embryo- 

 logical knowledge and methods equally were at his disposal, and 

 he employed all of these whenever it was necessary for the 

 accomplishment of his purpose at the time. 



The philosophy of nature experienced its most luxuriant growth 

 during this time under the influence of the ideas of Schelling and 

 Hegel, and with its unbridled speculation, which lacked all basis 

 of fact, seriously threatened scientific investigation. But it exer- 

 cised only the most beneficent effect upon the rigorously critical 

 mind of Miiller. He recognised in the ambitious tendencies of 

 the natural philosophers a germ of truth, and under its influence 

 fashioned his own manner of scientific investigation into a genuinely 

 philosophical type. While keeping constantly in view the large 



1 The most important estimate of Johannes Miiller is to be found in the 

 memorial address upon him given by du Bois-Reymond ('59). 



