94 



the infant by the mother's breath and breast, by the ap- 

 plication of a handkerchief to the child's nostrils, etc. 



Yet time permits a reference, and that but brief, to 

 one of the most important the possibility of infection 

 from tuberculous meat and milk. For the so-called pearl 

 disease of cattle, while presenting certain histological 

 differences an excess of calcareous salts, ascribable to 

 their vegetable food from tuberculosis in man and other 

 animals, would seem to have an identical etiology ; since 

 inoculation with minute pieces into the anterior chamber 

 of the rabbit's eye gives precisely the same result local 

 and general tuberculosis as is induced by the same 

 quantity of human tuberculous tissue and by nothing else. 

 The effects of introducing the two into the circulation are 

 also identical. Indeed there now remain but few who 

 are not satisfied of the etiological identity of the two pro- 

 cesses, especially since Koch's bacillus is found to in- 

 habit both tissues. Yet etiological identity does not 

 prove the possibility of infecting the human subject 

 with tuberculous meat and milk. For it is a principle 

 that must be borne in mind a principle which Pas- 

 teur, in his ideas of preventive vaccination seems to 

 have forgotten, by the way that a material which 

 can infect a given animal when placed in the eye, may 

 fail when introduced into the alimentary canal or even 

 under the skin. Koch found, five years ago, that al- 

 though a mouse is so susceptible to anthrax as to be a 

 reliable reagent in testing the strength of anthrax material 

 when introduced subcutaneously, yet all attempts to in- 

 duce the disease in mice, as well as in rabbits, by feeding 

 them with anthrax tissues or spores, were quite unsuc- 

 cessful. Since anthrax bacilli grow best in a somewhat al- 

 kaline liquid, and not at all in one markedly acid, the 

 explanation may lie in the general acidity of the gastric 

 and intestinal secretions in certain animals. But what- 

 ever the explanation the fact remains. 



Many experiments have been made to determine the 

 possibility of infecting animals by feeding them with tis- 

 sues and milk from tuberculous cattle. Gerlach, Orth, 



