TRANSACTIONS OF SECTION I. 773 



almost be counted on the fingers of one hand, and when chemists looked -^ith 

 scarcely veiled contempt on -what was at that time called physiological chemistry: 

 they stated that physiologists dealt with messes or impm-e materials, and therefore 

 anything in the nature of correct knowledge was not possible. There was a good 

 deal of truth in these statements, and if physiologists to-day cannot quite say that 

 they have changed all that, they can at any rate assert with truth that they are 

 changing it. This is due to a growing rapprocliement between chemists and 

 physiologists. Many of our younger physiologists now go through a thorough 

 preliminary chemical training ; and on the other hand there is a growing number 

 of chemists — of whom Emil Fischer may be taken as a type — who are beginning to 

 recognise the importance of a systematic study of substances of physiological 

 interest. A very striking instance of tliis is seen in the progress of our knowledge 

 of the carbohydrates, which has culminated in the actual synthesis of several 

 members of the sugar group. Another instance is seen in the accxirate informa- 

 tion we now possess of the constitution of uric acid. When Miescher began hia 

 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 formation of uric acid and other substances of the purine 

 family. Already the chemical relationships of uric acid and nuclein have taught 

 practical 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 labouring 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 

 protoplasm. 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 understanding 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 labelling it as vital or something we 

 can never hope to imderstand 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 

 regular 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 ulti- 

 mately be found to be subservient to such laws. 



Let me take as an example the subject of osmosis. The laws which regulate 

 this phenomenon through dead membranes are fairly well known and can be 

 experimentally verified ; but in the living body there is some other manifestation 

 of force which operates in such a way as to neutralise the known force of 

 osmosis. Is it necessary to suppose that this force is a new one ? May it not 

 rather be that our much vaunted knowledge of osmosis is not yet complete ? It 

 is quite easy to understand why a dead and a living membrane should behave 

 difierently in relation to substances that are passing through them. The 



