ON THK VJTALISTIC VIEW OF NATURE. 419 



in the examination of dead embryos in various stages 

 of development, and the idea of the division of labour 

 is one flowing from the premises of the Darwinian 

 theory the facts of variability and overcrowding. The 

 second conception, that of " metabolism," touches im- 

 mediately upon the processes of life, and demands 

 special treatment in the present chapter which deals 

 with biological Thought. 



The conception of a continuous exchange or circulation 

 of matter and of energy in every living organism, and 

 the study of this elementary typical form of the living 

 process in the morphological unit of all living or- 

 ganisms, in the cell, seems to have originated with 

 Theodor Schwann, 1 and is laid down in his ' Micro- si. 



Schwann. 



scopical Researches,' published in 1839. On it is based 

 the whole simplification and unification of biological 

 thought which distinguishes the second from the first 

 half of our century. The study of the cell its 



1 On the change which came that the first instance in which 

 over general physiology about 1840, an "evidently vital phenomenon 

 and the part he himself played, W as submitted to mathematical. 

 Theodor Schwaun has expressed numerical " rule, was his measure-' 

 himself in a letter addressed to ment of the crying power of 

 Du Bois-Reymond, which is g_iven j a musc i e i n relation to its con- 

 in the notes to the latter's Kloge i traction in 1836. The purely 

 of Muller, reprinted in the second physical view of vital phenomena 

 volume of his 'Reden,' pp. 143-334. exhibited in this example was not 

 It forms one of the most im- j adopted by Muller, nor yet the 

 portant historical documents. The j quickly following general principle 

 Eloge itself should be read together j of the cellular theory. Schwann 

 with Claude Bernard's ' Rapport,' j refers to the third section of his 

 &c., mentioned above (p. 384 n. ), ' Microscopical Researches, ' in 

 which gives the history of the great which he discards "vitalism," but 



change from a more exclusively 



admits in man ("on account of 



French point of view. In the ' his freedom ") an immaterial prin- 



letter mentioned above, from which ciple, and claims that this assump- 



also the quotations given in the tion divides him distinctly from the 



text are taken, Schwann claims materialists. 



