W. a. STEVENSON. 101 -(7l) 



shown by the excreted products of decomposition, 

 and increased muscular action, as evidenced in the in- 

 creased circulation of the blood. Physical conditions. 

 therefore, determine mental results. The higher nerve 

 tissue of the brain operates under physical and chemical 

 conditions in its nutrition, the same as does the tissue of 

 any other organ, and hence its transformed energy, as 

 expressed in nervous or mental action, has its physiologi- 

 cal representation, and measurable force. 



To extend this subject farther in the line of analysis, 

 though it would be interesting, is unnecessary for the 

 object proposed, which is to show that chemical, physi- 

 cal and biological sciences have overthrown and destroyed 

 the vitalistic doctrines of the past, and. demonstrated by 

 analysis a relationship between the forces which 

 rule the inorganic world and the "vital force, " which is 

 manifested in living forms. At this point the question 

 is properly asked, if chemical synthesis comfirms the re- 

 sults and conclusions of chemical analysis. 



If the morphology and physiology of organisms are 

 the products simply of physical molecules under chemi- 

 cal and physical forces which are revealed by analysis, 

 then the assumption seems justified that synthesis, by 

 combining these same molecules and restoring these same 

 forces, should be able to reproduce the forms and func- 

 tions of life. 



Synthesis requires exact knowledge of all the elements 

 and forces involved in the object of its investigation, and 

 looks to the inductive or analytic method to furnish these 

 data. There must be no unknown quantities in the prob- 

 lem to be solved, for synthesis seeks not to build from 

 the unknown but onl\ to reform the known. Hence it 

 properly awaits to receive verified facts from chemical 

 analysis, which has yet been able to compass but a frac- 

 tional part of the organic compounds. 



Chemical elements are the basis of chemical science • 

 they are neither produced nor destroyed, but are the en- 

 during and constant factors in the many series of 

 changes in the properties of matter, which represent the 

 desideratum of this science. And yet the knowledge of 

 molecules is very meagre, the weights of but a few 

 are known, even among the commonest . elements and 

 compounds ; and but little account has been taken of 



