William O. Reinhardt 



495 



animals to a cold atmosphere. Female rats averaging 210 gm. in body weight 

 were subjected to exposure in the cold room for a period of 63 hours to a tem- 

 perature of 36-38° F. and a further exposure to a temperature of 25° F. for 

 a period of three hours. The animals were placed in individual wire-bottom 

 metabolism cages and allowed free access to 1 per cent sodium chloride solu- 

 tion as a source of drinking water. The groups employed consisted of normal 

 fasted animals maintained at room temperature, a group exposed to cold and 

 fasted, and a third group which was allowed food ad libitum in the cold. The 



TABLE 4 

 Weights of Thymus, Spleen, and Lymph Nodes in Rats Exposed to the Cold 



* Organ weights in milligrams. Figures in parentheses represent ranges within each group. 



thymus, spleen, cervical, and mesenteric nodes were weighed. The data ob- 

 tained are presented in table 4. 



It would seem reasonable and in agreement with Selye' to conclude that ex- 

 posure to cold constitutes a stimulus which will cause a significant absolute- 

 weight reduction in the organs studied and that this weight reduction may be 

 partially prevented by the administration of food. 



Relationships between Endocrines and the Thymus, Spleen, 



AND Lymph Nodes 



Experiments involving the effect of certain hormonal treatments or deficien- 

 cies on the thymus have in turn led to a consideration of the role of certain 

 endocrine glands in affecting the gross amount of lymph-node tissue in the 

 body. 



In this laboratory, studies have been made of the effect of adrenalectomy, 

 castration, and hypophysectomy. The adrenalectomized animal maintained 

 on 1 per cent NaCl solution has shown significant increases in certain of the 

 lymph-node groups (Reinhardt and Holmes*). Castration causes a significant 

 enlargement of thymus, spleen, and lymph nodes (Reinhardt and Wainman"). 

 These findings are in accord with those of Chiodi' and of Houssay and co- 

 workers.^" Preliminary studies show that hypophysectomy causes a decrease in 

 the weight of thymus, spleen, and cervical lymph nodes, but not of the mesen- 

 teric lymph nodes. Administration of desiccated thyroid gland orally to nor- 



