296 



INANITION AND MALNUTRITION 



medulla darker in appearance. The formation of HassaH's corpuscles from 

 the epithelioid cells continues. At 4 days, "delymphoidisation" is complete 

 and there is but slight distinction between cortex and medulla. Mitoses have 

 entirely disappeared; Hassall's corpuscles become cystic and are destroyed by 

 eosinophiles. Recovery of the rat upon refeeding is impossible at this stage, 

 but occurs after 2 days of starvation. The process of "relymphoidisation" is 

 somewhat slow, mitoses appearing rare after 48 hours of refeeding. At least 

 a week is required to re-establish the normal lymphoid structure. A chick 



Fig. 80. Fig. 81. 



Fig. 80. — Photograph of a cross section of the thymus in a normal albino rat (S. 2) at 3 

 weeks of age. The gland is mostly cortex, the few light areas representing the medulla. The 

 capsule and interlobular septa are thin. A, perithymic adipose tissue. Zenker fixation; 

 alum-hematoxylin stain. X22. 



Fig. 81. — Photograph of a cross section of the thymus in an albino rat (S. 11) held at 

 constant body weight by underfeeding from 3 to 10 weeks of age. The thymus is greatly 

 reduced in size, and the distinction between cortex and medulla obliterated. The capsule and 

 interlobular septa are relatively thickened. Some masses of atrophic, perithymic adipose 

 tissue (A) are included in the section. Zenker fixation; alum-hematoxylin stain. X22. 



(a few days old) after 12 hours' starvation showed beginning "delymphoidisa- 

 tion," similar to that in mammals. Lizards starved 1-5 weeks also showed 

 the typical thymic involution, but a teleost fish ("Chat de Mer") showed no 

 appreciable change in 6 days. 



Some of the changes observed in the weight of the thymus of the albino rat 

 during inanition by Jackson and his co-workers are shown in Table 4. In rats 

 underfed from the age of 3 weeks to 10 weeks, Jackson ('15a) noted a loss of 

 about 90 per cent in the thymus. In rats underfed from birth for various 



