20 REPOET— 1887. 



of preparing a compound which will possess certain desired physiological 

 properties, or even to foretell the kind of action which such bodies may 

 exert on the animal economy. 



But it is not only the physiological properties of chemical compounds 

 which stand in intimate relation with their constitution, for we find that 

 this is the case with all their physical properties. It is true that at the 

 beginning of our period any such relation was almost unsuspected, whilst 

 at the present time the number of instances in which this connection has 

 been ascertained is almost infinite. Amongst these perhaps the most 

 striking is the relationship which has been pointed out between the 

 optical properties and chemical composition. This was in the first place 

 recognised by Pasteur in his classical researches on racemic and tartaric 

 acids in 1848 ; but the first to indicate a quantitative relationship and a 

 connection between chemical structure and optical properties was Glad- 

 stone in 1863. Great instrumental precision has been brought to bear on 

 this question, and consequently most important practical applications 

 have resulted. I need only refer to the well-known accurate methods 

 now in everyday use for the determination of sugar by the polariscope, 

 equally valuable to the physician and to the manufacturer. 



But now the question may well be put, is any limit set to this 

 synthetic power of the chemist ? Although the danger of dogmatising 

 as to the progress of science has already been shown in too many in- 

 stances, yet one cannot help feeling that the barrier which exists between 

 the organised and unorganised worlds is one which the chemist at pre- 

 sent sees no chance of breaking down. 



It is true that there are those who profess to foresee that the day 

 will arrive when the chemist, by a succession of constructive efforts, may 

 pass beyond albumen, and gather the elements of lifeless matter into 

 a living structure. Whatever may be said regarding this from other 

 standpoints, the chemist can only say that at present no such problem lies 

 within his province. Protoplasm, with which the simplest manifestations 

 of life are associated, is not a compound, but a structure built up of com- 

 pounds. The chemist may successfully synthesise any of its component 

 molecules, but he has no more reason to look forward to the synthetic 

 production of the structure than to imagine that the synthesis of gallic 

 acid leads to the artificial production of gall-nuts. 



Although there is thns no prospect of our eflfecfcing a synthesis of 

 organised material, yet the progress made in our knowledge of the 

 chemistry of life during the last fifty years has been very great, and so 

 much so indeed that the sciences of physiological and of pathological 

 chemistry may be said to have entirely arisen within this period. 



In the introductory portion of this address I have already referred 

 to the relations supposed to exist fifty years ago between vital phenomena 

 and those of the inorganic world. Let me now briefly trace a few of 

 the more important steps which have marked the progress of this branch 

 of science during this period. Certainly no portion of our science is of 



