564 OF SECRETION. 



seven hours later, when no food has been taken in the interval. Hence he 

 inferred, that this organ is the receptacle for the increased quantity of Blood 

 which the system acquires from the food, and which cannot, without danger, 

 be admitted into the blood-vessels generally ; and that it regains its previous 

 dimensions, after the volume of the circulating fluid has been reduced by 

 secretion. This view is confirmed by the fact noticed by several observers, 

 that the Spleen rapidly increases in bulk after the ingestion of a large quantity 

 of fluid, which is absorbed rather by the Veins than by the Lacteals. It has 

 been further stated in support of this theory, that animals from which the 

 Spleen has been removed, are very liable to die of apoplexy, if they take a 

 large quantity of food at a time ; but that, if they eat moderately and frequently, 

 they do not suffer in this manner. The use of the Spleen as a diverticulum 

 for the internal Venous circulation, is further borne out by its liability to be- 

 come enlarged in consequence of intermittent fever ; during the cold stage of 

 which, a great quantity of blood is driven from the surface towards the internal 

 organs ; and it may be easily imagined that, if there were no such reservoir, 

 the congestions in these would be much more dangerous than those which 

 actually do occur. The permanent enlargement of the organ is, of course, on 

 this idea of its use, a result of its frequent distension. That the function of the 

 Spleen is in some way connected with that of Digestion, appears from the fact 

 of the small size of this organ in the foetal state. 



710. The Supra-Renal Capsules, like the Kidneys, consist of two distinct 

 kinds of substance, a cortical and medullary. The cortical substance is of a 

 yellowish colour, and consists of straight parallel fibres arranged side by side. 

 Of these straight fibres, a large part are branches of arteries which enter this 

 body at every point of its exterior, from a capillary net-work covering its sur- 

 face ; and others are corresponding branches of veins, that receive the blood 

 from these arteries, and convey it into a venous plexus, of which the medullary 

 substance is chiefly composed. By the union of the veins of this plexus, is 

 formed the large central vein of the organ ; and this is the only cavity which 

 it contains. No apparatus of secreting tubes or cells can be detected in it ; 

 and its function is entirely unknown. The interspaces of the vessels are 

 filled up by a sort of pulp, which, according to Mr. Gulliver (Op. cit. p. 103), 

 is composed of very minute oil-like spherules, very unequal in their size, 

 varying from 1 -24,000th to 1 -6,000th of an inch in diameter, their average 

 size being about l-10,000th. These spherules are but little affected by 

 chemical reagents, and their nature is very uncertain. In many Ruminant 

 animals, the minute spherules are less plentiful ; their place being supplied by 

 corpuscles that somewhat resemble Lymph-globules in size, but are often of a 

 reddish colour, and occasionally of an oval figure. These are sometimes 

 found in the Human subject also, particularly in early life. The blood of the 

 Supra-Renal vein has been observed to contain numerous minute spherules, 

 which cannot be distinguished from those of the gland ; similar particles, 

 however, may be detected in the blood of other parts ; and the identity of these 

 is still a matter of doubt. The Supra-Renal capsules, as already mentioned 

 ( 667), attain a large size very early in foetal life ; surpassing the true Kid- 

 neys in dimension, up to the tenth or twelfth week. As is the case in the 

 Spleen, the Lymphatics are of large size; these terminate in the lumbar 

 glands. Their Arteries are derived from the aorta, the renal, and the phrenic ; 

 their veins open into the vena cava on the right side, and into the renal vein 

 on the left. The only use that can be assigned to them with any probability, 

 is that of serving as a means of conveying into the Veins the blood transmitted 

 through the Renal Artery ; when from any cause the secreting function of the 

 Kidneys is partly or entirely checked, and their capillary circulation in con- 

 sequence stagnated. This idea seems to derive confirmation from the fact, 



