362 ANNUAL OF SCIENTIFIC DISCOVERY. 



effect upon the animals. Some cider which had proved very inju- 

 rious to the health of those who had used it, was found, on examina- 

 tion by M. Pierre, to contain considerable quantities of butyric acid, 

 but no other substance to which the bad effects could be ascribed. 



There is no reason to doubt that butyric acid might, under abnor- 

 mal circumstances, be produced in the body in considerable quantity. 

 Many substances which, under normal digestive functions, may be 

 favorably assimilated, might, in peculiar states of the body, scarcely 

 amounting in themselves to absolute disease, be converted into butyric 

 acid, which, according to Leopold Grnelin, is produced under the fol- 

 lowing circumstances : 



Starch and sugar, in contact with proteine substances, are gradu- 

 ally converted into butyric acid, with or without previous conversion 

 into lactic acid. Grape sugar in solution, which does not of itself 

 ferment, may be made to do so by immersion of bits of paper previ- 

 ously exhausted by chlorhydric acid and water, with production of 

 butyric acid. The residue from the manufacture of potato starch, 

 which contains considerable quantities of starch, if mixed with small 

 quantities of animal matter, undergoes fermentation in two or three 

 days, with production of butyric acid. Large quantities of the same 

 acid are formed when starch remains in contact with animal matters 

 for a few days, and under other circumstances which might occur in 

 the human system. 



In confirmation of this view, it may be mentioned that butyric acid 

 has actually been detected in the gastric juice, and in the matter 

 from a cancer in the stomach. Butyric acid may even be in very 

 small quantity an occasional or even normal constituent of certain 

 parts of the body. But, under unfavorable conditions of the diges- 

 tive functions, it may easily be produced in sufficient quantity to ex- 

 ercise a noxious influence on the organism. 



Butyric acid is, in all these cases, an oxidation product, as is 

 proved by the fact that the same substances, starch, sugar, gluten, 

 etc., yield it by treatment with nitric acid, sulphuric acid, and perox- 

 ide ef manganese, or chromic acid. If, therefore, it could be demon- 

 strated that any particular form of disease was occasioned by the 

 presence of butyric acid, such disease might, no doubt, be successfully 

 combated by deoxidizing agents, such as sulphur baths. 



CONFOKMATION OF THE TEETH IN THE INFERIOR VARIETIES 



OF MAN. 



The conformation of the teeth in the inferior varieties of man pre- 

 sents some curious approximations to the dental structure of the ape. 

 In the latter, the pre-molars, or bicuspids, are implanted by three 

 fangs. In the Caucasian race of man they generally have, seemingly, 

 only one fang, which, however, consists of two more or less completely 

 united ; but in negroes these teeth have two distinct fangs. " It is 

 only in the black varieties," says Professor Owen, in his admirable 

 paper on the teeth, " and more particularly that race inhabiting Aus- 

 tralia, that I have found the wisdom tooth with three fangs as a gen- 

 eral rule ; and the two outer ones are more or less confluent." In 

 most of the black varieties of man, especially the Australians, "the 



