3 o POPULAR SCIENCE MONTHLY. 



culminated in the actual synthesis of several members of the sugar 

 group. Another instance is seen in the accurate information we now 

 possess of the constitution of uric acid. When Miescher began his 

 work on the chemical composition of the nuclei of cells, and separated 

 from them the material he called nuclein, he little foresaw the wide 

 practical application of his work. We now know that it is in the 

 metabolism of cell-nuclei that we have to look for the oxidative forma- 

 tion of uric acid and other substances of the purine family. Already 

 the chemical relationships of uric acid and nuclein have taught prac- 

 tical physicians some of the secrets that underlie the occurrence of 

 gout and allied disorders. 



With the time at my disposal, it would be impossible to discuss all 

 the chemico-vital problems which the physiologists of the present 

 day are attempting to solve, but there is one subject at which many 

 of them are laboring which seems to me to be of supreme importance 

 I mean the chemical constitution of proteid or albuminous substances. 

 Proteids are produced only in the living laboratory of plants and 

 animals; proteid metabolism is the main chemical attribute of a living 

 thing; proteid matter is the all-important material present in proto- 

 plasm. But in spite of the overwhelming importance of the subject 

 chemists and physiologists alike have far too long fought shy of 

 attempting to unravel the constitution of the proteid molecule. This 

 molecule is the most complex that is known: it always contains five, 

 and often six, or even seven elements. The task of thoroughly under- 

 standing its composition is necessarily vast, and advance slow. But 

 little by little the puzzle is being solved, and this final conquest of 

 organic chemistry, when it does arrive, will furnish physiologists with 

 new light on many of the dark places of physiological science. 



The revival of the vitalistic conception in physiological work appears 

 to me a retrograde step. To explain anything we are not fully able to 

 understand in the light of physics and chemistry by labeling it as 

 vital or something we can never hope to understand is a confession 

 of ignorance, and, what is still more harmful, a bar to progress. It 

 may be that there is a special force in living things that distinguishes 

 them from the inorganic world. If this is so, the laws that regulate 

 this force must be discovered and measured, and I have no doubt that 

 those laws when discovered will be found to be as immutable and regu- 

 lar as the force of gravitation. I am, however, hopeful that the 

 scientific workers of the future will discover that this so-called vital 

 force is due to certain physical or chemical properties of living matter 

 which have not yet been brought into line with the known chemical and 

 physical laws that operate in the inorganic world, but which as our 

 knowledge of chemistry and physics increases will ultimately be found 

 to be subservient to such laws. 



