NATURAL AND ACQUIRED IMMUNITY 105 



removal of either the adrenals or the hypophysis does not affect 

 antibody formation. He did find that anaphylactic shock could be 

 produced in hypophysectomized cats but not in the normal con- 

 trols. 



Age AND Resistance. — It is generally recognized that in the 

 clinical entity known as "status lymphaticus" where the thymus 

 gland does not undergo its normal involutionary changes, the child 

 is quite susceptible to intercurrent infections. Clinical experience 

 has also established the fact that at both extremes of life the in- 

 dividual possesses relatively little capacity to combat the majority 

 of infectious diseases. The relationship of age to immunological 

 reactions is discussed at some length by Baumgartner (1934), but 

 her paper refers only to the humoral elements (antibodies). In 

 this connection the work of Sutliff and Finland (1932) is very 

 suggestive. They investigated the bloods of individuals falling 

 into various age groups relative to the content of agglutinating, 

 mouse protecting and bactericidal antibodies for various strains 

 of pneumococci. In regard to mouse protecting and pneumococ- 

 cidal antibodies Finland and Sutliff (1932) observed that they are 

 relatively rare in the blood of children, relatively frequent in 

 adults, and less frequent in elderly individuals. They regard 

 the frequency curve for pneumococcidal power as probably similar 

 for all types, showing a peak in adult life. 



That the process of aging is associated with increasing resistance 

 to certain viruses is indicated by the work of Olitsky, Sabin and 

 Cox (1936), King (1940) and Casals (1940). Of added interest 

 are the reports of Culbertson and Kessler (1939), Morgan (1939), 

 and Casals and Webster with rabies infection in mice. In later 

 work Casals (1940) finds that in the case of rabies, the influence of 

 age in immunizability is evident only under definite sets of con- 

 ditions. 



Warthin (1929) discusses the anatomical changes that take place 

 from conception to old age and death, but does not attempt to 

 correlate structural and functional change with the relative in- 

 tegrity of the defensive mechanisms of the body. In view of the 

 apparent increase in interest in the relationship of the aging 

 process to immunity these publications are timely and suggestive. 



Vitamins and Food Factors in Resistance. — The importance of 

 vitamin A in the defense of the body against infectious agents is 



