37i THE HISTORY OF BIOLOGY 



he worked. One of his most important contributions, however, is his inves- 

 tigation of the substances that are produced by life on the earth. In his Lec- 

 tures on Animal Chemistry, published during the years 1806-8, he expounds 

 his conception of life-phenomena in general and, besides, records a number 

 of fresh facts in the sphere of organic analysis, which he later still further 

 augmented. These purely chemical investigations into the composition of 

 blood, gall, milk, bone, fat, and many other elements, really belong to the 

 science of chemistry rather than to biology; although they exercised a fun- 

 damental influence on the knowledge of life and the functions of the living 

 body during the succeeding period, a detailed account of their results would 

 hardly be in place here, but the views on the phenomena of life which Ber- 

 zelius formed as a result of these investigations have naturally played an 

 important part, both in his own time and in the age that followed; an ac- 

 count of them is therefore of interest, quite apart from the interest always 

 excited by ideas expressed by one of the great pioneering personalities of 

 the world. 



As sources from which he derived his view of the phenomena of life 

 Berzelius mentions first of all the works of Bichat and Fourcroy; in partic- 

 ular, the former's explanation of the tissues of the body and their functions 

 formed the basis of his entire conception of life-phenomena. Reil, too, con- 

 tributed largely thereto, while Fourcroy's role was primarily that of a pre- 

 cursor in the purely chemical sphere. What chiefly distinguishes Berzelius's 

 general conception of nature from the conceptions of his predecessors is his 

 severe criticism of and opposition to any kind of "hypothesis-mongering." 

 While contemporary natural philosophy created brilliant thought-systems, 

 Berzelius introduces his "animal chemistry" with the words: "I have every- 

 where sought to avoid hypothesis, and where I have at any time ventured 

 to make insignificant guesses, they are all of such a nature that they will 

 soon be decided by experience. I prefer to say: 'This is entirely unknown to 

 us,' than to try by means of a number of probabilities to gloze over a gap 

 in our knowledge." 



Berzelius rejects vitalism 

 In conformity with this principle he rejects the vitalistic theories of his 

 age: "Life does not lie in any extraneous essence deposited in an organic 

 or living body; its origin must be sought in the common fundamental forces 

 of primal elements, and this is a necessary consequence of the condition 

 wherein the elements of the living body are combined." And further on he 

 says: "All, therefore, that we explain with the words ' oim vitality^ is 

 entirely unexplained and it is an illusion if they are given any other meaning 

 than that of a still unknown mechanico-chemical process." Even the func- 

 tions of the soul are explained in the same way: "Unreasonable as it may 

 seem . . . nevertheless, our judgment, our memory, our reflections, as well 



