INFECTION AND IMMUNITY .16 1 



Smith, 1 noted that an actively immunized female 

 parent may transmit antibodies to the immediate 

 young, who, receiving the immunity passively, soon 

 lose it again. The male parent is unable to trans- 

 mit any immunity. In his classical studies with 

 ricin and abrin, Ehrlich showed that lactation 

 played an important part in the transmission of 

 immunity from female mice to their immediate off- 

 spring. By immunizing a nursing mother mouse 

 (after the birth of the litter) he was able to demon- 

 strate the transmission of immunity to swine plague 

 to the nursing young. Smith, on the other hand, 

 in his experiments with guinea pigs, immunized 

 against diphtheria toxin, found that lactation played 

 no appreciable part in the passive immunity of the 

 young. Salge nursed infants with the milk of 

 goats which had been immunized against diphtheria 

 and against typhoid, and was unable to'demonstrate 

 the passage of antibodies to the infants. 



In contrasting active with passive immunization 

 we may say that the former is usually more effect- 

 ive, more lasting, and productive of a general 

 immunity and not merely of one particular kind. 

 It is, however, sometimes difficult to carry out, 

 may involve some risk to the patient, and takes 

 time. Passive immunization, on the other hand, 

 is usually productive of only a limited kind of 

 immunity, i.e., antitoxic, bactericidal, opsonic, etc., 



1 Smith, Jour. Exper. Med., Vol. xi, 1909. 



