4i 8 THE DUCTLESS GLANDS. 



without immediate danger to life. Nor, indeed, would 

 this be certainly sufficient, since there is reason to suppose 

 that the duties of the spleen, after its removal, might be 

 performed by lymphatic glands, between whose structure 

 and that of the vascular glands there is much resemblance, 

 and which, it is said, have been found peculiarly enlarged 

 when the spleen has been removed (Meyer). 



Although the functions of all the vascular glands may 

 be similar, in so far as they may all alike serve for the 

 elaboration and maintenance of the blood, yet each of th'em 

 probably discharges a peculiar office, in relation either to 

 the whole economy, or to that of some other organ. 

 Eespecting the special office of the thyroid gland, nothing 

 reasonable can be suggested; nor is there any certain 

 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 the 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, recent investi- 



* 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, de- 

 monstrated 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. 



