41 6 THE DUCTLESS GLANDS. 



evidence concerning that of the supra-renal capsules.* 

 Respecting the thymus gland, the observations of Mr. 

 Simon, confirmed by those of Friedleben, and others, have 

 shown that in the hybernating animals, in which it exists 

 throughout life, as each successive period of hybernation 

 approaches, the thymus greatly enlarges and becomes laden 

 with fat, which accumulates in it and in fat-glands connected 

 with it, in even larger proportions than it does in the 

 ordinary seats of adipose tissue. Hence it appears to serve 

 for the storing up of materials which, being re-absorbed in 

 inactivity of the hybernating period, may maintain the 

 respiration and the temperature of the body in the reduced 

 state to which they fall during that time. 



With respect to the office of the spleen, we have 

 somewhat more definite information. In the first place, 

 the large size which it gradually acquires towards the ter- 

 mination of the digestive process, and the great increase 

 observed about this period in the amount of the finely- 

 granular albuminous plasma within its parenchyma, and 

 the subsequent gradual decrease of this material, seem to 

 indicate that this organ is concerned in elaborating the 

 albuminous or formative materials of food, and for a time 

 storing them up, to be gradually introduced into the blood, 

 according to the demands of the general system. The 

 small amount of fatty matter in such plasma, leads to the 

 inference that the gland has little to do in regard to the 

 preparation of material for the respiratory process. 



* Mr. J. Hutchinson, and, more recently, Dr. "Wilks, following out 

 Dr. Addison's discovery, have, by the collection of a large and valuable 

 series of cases in which the supra-renal capsules were diseased, demon- 

 strated most satisfactorily the very close relation subsisting between 

 disease of these organs and brown discoloration of the skin ; but the 

 explanation of this relation is still involved in obscurity, and conse- 

 quently does not aid much in determining the functions of the supra- 

 renal capsules. 



