960 INFLUENCE OF DUCTLESS GLANDS ON METABOLISM. 



in some animals, e.g. rabbits, after extensive blood-letting, nucleated 

 erythroblasts, .such as those which are found in bone-marrow, occur 

 both in the spleen pulp and in the blood of the splenic vein ; and that 

 if a spleenless animal is bled, the recovery of the usual percentage of 

 red corpuscles is less rapid than in a normal animal. 1 



Whatever may be the nature of its functions in relation to the blood, 

 it is certain that the organ is in no way essential to the normal 

 nutrition of the body. It is, on the other hand, not at all improbable 

 that the main function of the spleen is to serve a mechanical pur- 

 pose, answering as a reservoir at certain periods of digestion fo;r the 

 blood which has to pass through the portal system ; and the fact that, 

 as was first shown by Eoy, the spleen normally exhibits regular rhythmic 

 contractions and dilatations, seems to point to its exercising an influ- 

 ence in assisting the flow of blood through the portal vein, and thus 

 through the liver. 2 



1 Laudenbach, Arch, de physiol. norm, etpath., Paris, 1897, pp. 200, 385, and 893. 



2 The functional connection of the spleen with the vascular system is dealt with in the 

 article on " Circulation " in the next volume. Extracts and decoctions of spleen appear to 

 have no specific effect, either when injected snbcutaneously or intravenously. Nor is any- 

 thing known as to any specific functions possessed by the thynms. body or by the carotid 

 and coccygeal glands. Extracts and decoctions of the thynms appear to have no specific 

 effect when injected intravenously (Oliver and Sehafer. Journ. PhysioL, Cambridge and 

 London. 1895, vol. xviii.) or subcutaneously (Vincent, ibid., 1897, vol. xxii.). It has 

 been stated that removal of the thy mu s in frogs is followed by a fatal result (Abelous and 

 Billard, Arch, de physiol. norm, et path., Paris, 1896, p. 898), but the statement requires 

 corroboration. 



