484 IMMUNOLOGY 



eighteen hours with regular rhythm. They remained desensitized 

 throughout this period. 



4. Reversed anaphylaxis was not demonstrated in seven turtles, 

 but a doubtful positive was obtained in one. The incubation 

 period for the latter was two hours. 



5. The shortest incubation period for passive sensitization was 

 four hours, while the average was twenty-four to forty-eight 

 hours. 



6. High titered immune serum from rabbits failed to sensitize 

 passively in a series of sixteen turtles. 



The subject of active sensitization in turtles was investigated 

 by Downs (1928). Her results may be summarized as follows: 



1. Turtles may be actively sensitized to mammalian serum. 



2. The heart in situ responds in a specific characteristic way 

 to the injection of antigen used for sensitization. 



3. Desensitization can be demonstrated. 



4. Precipitins (titer 1:10 to 1:100) are present in the serum of 

 a certain number of the actively sensitized animals, and this serum 

 seems to confer passive anaphylaxis to normal turtles. 



5. The specific response resembles vagus stimulation of the 

 turtle heart. 



Anaphylaxis in Chickens. — In 1926 Gahringer demonstrated 

 clinical anaphylaxis in chickens. It is characterized by profound 

 weakness, and lacrimation. The following year Hanzlik et al. 

 (1927) described the smooth muscle reaction of the crop in 

 pigeons. Sherwood (1928) reported upon his attempt to sen- 

 sitize the embryonic chick passively. He found that high titered 

 immune rooster serum will passively sensitize a very small per- 

 centage of 48- to 72-hour chick embryos. The characteristic 

 response is a marked slowing of the heart with a final cessation 

 in diastole. When the bath is changed, the heart will resume the 

 normal rhythm. The latter is not affected by another dose of 

 antigen. In other words, desensitization can be demonstrated. 

 He produced also reverse anaphylaxis in a few embryos. 



Anaphylaxis in Monkeys.— Monkeys are apparently very re- 

 fractory to anaphylaxis. Coca (1927) and Zinsser, Enders, and 

 Fothergill (1939) cite the work of Auer and others who were un- 

 able to demonstrate anaphylaxis in monkeys. Zinsser states that 



