ORGANS OF THE BODY. 439 



the sympathetic, consist principally, and not uiifrequently almost exclu- 

 sively of pale elements already known under the name of Remaps fibres. 

 They enter at the hilus, and pursue the same course as the ramifications 

 of the arteries. The number of nerves supplying the organ is very con- 

 siderable as a rule, but their mode of termination, judging from Koel- 

 liker and BillroiKs observations in the sheep and ox, is still uncertain. 

 Division of their trunks was observed by Koelliker, and Ecker probably 

 saw terminal resolution. According to W. Muller, finally, there occur at 

 certain points of the splenic nerves groups of cells like ganglion cor- 

 puscles : once only did he succeed in tracing a fibre into a capillary 

 sheath in the spleen of a pig. We are tempted to ascribe to the struc- 

 tures in question a similar significance as the end capsules of Kruuse on 

 the gland nerves (p. 327). 



235. 



The spleen, whose sp. gr. is 1*058 (Krause and Fiaclier), contains 18- 

 30 per cent, of organic matter, and an average of O'5-l per cent, of 

 mineral constituents (Oidimann). 



That organic fluid of acid reaction, which saturates the tissue of the 

 spleen, contains, according to Scherer, Frerichs, Staedeler, Cloetta, and 

 Gorup, a large number of interesting substances. 



Among these may be named inosite, volatile fatty acids, e.g., formic, 

 acetic, and butyric, also succinic, lactic, and uric acids. Among the 

 bases we find, in the normal human spleen, considerable quantities of 

 leucin, and a moderate, that is comparatively large amount of tyrosin 

 (Frerichs and. Staedeler). Xanthin and hypoxanthin are also encountered in 

 the organ. Beside these, Sclierer succeeded in obtaining non-carbonaceous 

 pigments, a very interesting albuminous substance rich in iron, and much 

 iron combined, it appears, with acetic and lactic acids. The peculiar con- 

 stitution of the veins must provide for tho passage of these matters into 

 'Jie circulation, but up to the present no analysis of the blood of the 

 splenic vein has come upon them there (comp. p. 121). 



Special attention has been bestowed by Oidtmann upon the mineraJ con- 

 stituents, and among them he has found chlorine, phosphoric, sulphuric, 

 and silicic acids, potash and soda (the latter preponderating), lime, 

 magnesia, iron, manganese, and copper. 



Turning, then, to the physiological significance of the spleen, so fre- 

 quently a subject of debate, it is supposed to play an important part in 

 the economy of the blood. It is believed to be concerned, namely, in the 

 destruction of the blood-cells on the one hand ; on the other, in the repro- 

 duction of the same. The first of these views may be defended, but not 

 incontrovertibly proved in the present state of science ; for although, in 

 many spleens, the blood-cells are certainly very extensively destroyed, 

 still a doubt exists whether this is anything more than an accidental 

 occurrence. , The second theory appears, however, more capable of proof. 

 According to it the spleen may be regarded as analogous in function to 

 the lymphatic nodes, producing the colourless cells of the pulp, which, on 

 finding their wayinto the blood, are known there as white blood corpuscles, 

 and which possibly, in part at least, undergo ere they leave the cavernous* 

 portions of the tissue of the spleen a transformation into coloured cells. 

 The amount of blood in the organ, further, is influenced in various ways by 

 its fibrous and muscular elements. The elasticity of the former opposes 

 to every expansion an amount of resistance varying with the volume of 

 29 



