388 SCIENCE PROGRESS 



a hospital which contained on an average 300 patients suffering from this disease 

 was no longer required. 



Up to the present the most brilliant successes have resulted from the treatment 

 of diseases due to animal parasites ; but evidence is not wanting that similar 

 successes will soon be forthcoming in the case of diseases of bacterial origin. In 

 this connection organic compounds of copper and other metals are being in- 

 vestigated, and there is ground for hope that valuable remedies for tuberculous 

 infections may before long be found. 



Dietetics. — Recently the significance of hitherto unsuspected constituents of 



food has come to be recognised, and it is now realised that dietary factors which 



until lately have not received consideration are of cardinal importance in the 



maintenance of normal metabolism. It is now clear that in addition to what are 



known as the proximate principles — proteins, carbohydrates, fats, and salts — there 



are in a mixed diet minute amounts of certain substances which seem to be 



essential for the normal nutrition of the body. If, for any reason, these substances 



are absent or deficient, various disorders of metabolism, resulting in the production 



of characteristic symptoms, make their appearance. Beri-beri appears to be a 



disorder of this nature. It has been found associated with a diet of rice from 



which the pericarp has been removed by milling (polished rice). In the rice 



grain the essential substances above mentioned, for which the name " trophones " 



has been suggested, are located mainly in the pericarp. Beri-beri can be 



prevented by using rice from which the pericarp has not been removed, or by 



including in the diet foods which are rich in trophones. Polyneuritis, simulating 



many of the symptoms of beri-beri, has been produced in animals as a result 



of feeding them on a diet poor in trophones. Young animals fed on diets 



consisting of purified proteins, fats, and carbohydrates, even with the addition of 



salts and phosphatides, soon cease growing ; but the addition of minute amounts 



of fresh foods or tissue extracts is sufficient to ensure normal growth. 



The nature of these essential substances (trophones) is not yet precisely 

 known. There appear to be several substances concerned, of which the vitamine 

 of Kunk is probably one. They do not seem to exist free, but are probably 

 portions of more complicated molecules. Many of them are cyclic compounds, 

 purin and pyrimidin bases, which the animal seems incapable of synthesising, and 

 which, as sources of energy, are negligible. The trophones are unstable bodies, 

 and are injuriously affected by prolonged storage, by cooling, and by a variety of 

 other agencies. 



The nature of the salts in the food also appears to be of importance. There 

 is evidence to show that the ash of mixed foods is much more valuable than 

 an artificial mixture of salts corresponding in every chemical detail with the ash. 

 Possibly a minute trace of fluorine and manganese may be essential to proper 

 nutrition. 



Cardiac Pathology and Therapeutics. — In almost every branch of medical 

 science the application of exact methods of observation has been followed by the 

 discovery of important results. This is strikingly exemplified by the advances 

 which have been made in recent years in the physiology, pathology, and 

 therapeutics of the cardio- vascular system. In this field English workers have 

 been prominent. When the Congress was last held in London in 1881, much 

 mystery surrounded the mechanism of the heart's rhythm. Shortly before that 

 time Gaskell had begun his classical researches on the heart of the tortoise, 

 and had promulgated his theory of muscular conduction from chamber to 

 chamber without the intervention of nervous mechanism. This was followed by 



