248 BACTERIOLOGY. 



was not conveyed by direct inheritance. It was 

 instead an instance of extra-uterine, individual 

 immunization brought about by means of the 

 protective substances contained in the milk of 

 an immune mother or nurse. According to 

 Tizzoni, however, immunity to tetanus acquired 

 by the father can be transmitted to the off- 

 spring. 1 



The existence of a definite predisposition to 

 or immunity to disease is dependent upon the 

 inherited organization of the body, and, upon 

 its adaptation to the conditions of life, among 

 which may be numbered not only soil, water, 

 air, and the general factors of weather and cli- 

 mate, but also social conditions. These chang- 

 ing circumstances or external conditions act 

 upon the internal disposition which remains 

 always the same. If these conditions change, 

 then readjustment must occur, that is, changes 

 in the internal constitution must take place. 

 Every change in environment, every consider- 

 able change in nutrition may, therefore, make 

 itself felt by its effect upon our predisposition. 

 By utilizing the information gained from ex- 

 periments along this line we have at our dis- 

 posal a means of influencing the disposition in 

 our favor, as, for instance, by the removal of 



1 Later experiments have failed to confirm the statement that an 

 immune father can transmit immunity. E. O. J. 



