VITAMINES. 121 



alone the beat soon stops, with excess of potassium an immediate 

 paralysis occurs, and with excess of calcium an immediate rigor 

 or permanent contraction. Analogous results are obtained with 

 other muscles. Salts in certain proportions may even cause 

 .processes of cell division to start in the ova of some of the lower 

 animals. In other words, a process of embryo development may 

 which is usually induced by impregnation by the male 

 elements. 



Vitamines. Equally remarkable as adjuncts of diet is a class 

 of bodies called vitamines. Without them metabolism becomes 

 upset, and serious symptoms make their appearance with per- 

 haps death as the ultimate result ; and this happens even although 

 the protein, fat, carbohydrate and inorganic salts of the diet be 

 in proper proportion. The first indication of the importance 

 of vitamines was furnished by observations on a disease called 

 Beri-Beri, which occurs among peoples of tropical countries, and 

 is characterized by severe neuralgic pains, muscular weakness 

 and paralysis; symptoms which are due to inflammation of the 

 nerves (neuritis). It was noted that it occurred most frequently 

 in the case of people whose main article of diet was polished 

 rice, but was infrequent in the case of those using the unpol- 

 ished grain. The difference between these two grades of rice 

 is that the one (the unpolished) still contains some of the brown- 

 ish husk ; the other is free of it. This observation suggested the 

 experiment of adding some of the ground-up rice husks to the 

 polished rice diet of those suffering from the disease, with the 

 result that the symptoms soon disappeared. Moreover, when 

 unpolished rice was supplied, in place of polished rice, to natives 

 among whom Beri-Beri was very prevalent, the disease disap- 

 peared entirely. Other foodstuffs contain this vitamine, so that 

 Beri-Beri does not occur with mixed diets. 



In order to learn something more about these remarkable sub- 

 stances it was necessary to seek for some animal in which symp- 

 toms similar to those of Beri-Beri could be induced by feeding 

 with polished rice. Pigeons were found most suitable. When 

 these birds are kept exclusively on such a diet, they develop the 



