476 SECKETIOK 



for its excessively- tortuous course. In a man between forty and fifty years of age, 

 the vessel measured about five inches, without taking account of its deflections ; and a 

 thread placed on the vessel, so as to follow exactly all its windings, measured a little more 

 than eight inches. The large caliber of this vessel and its tortuous course are interesting 

 points in connection with the great variations in size and situation which the spleen is 

 liable to undergo in health and disease. The artery gives off several branches to the 

 adjacent viscera in its course, and, as it passes to the hilum, it divides into three or four 

 branches, which again divide so as to form from six to ten vessels. These penetrate the 

 substance of the spleen, with the veins, nerves, and lymphatics, enveloped in the fibrous 

 sheath, the capsule of Malpighi. In the substance of the spleen, the arteries branch 

 rather peculiarly, giving off many small ramifications in their course, generally at right 

 angles to the parent trunk. These are accompanied by the veins until they are reduced 

 to from ? V to tV f an mch in diameter. The two classes of vessels then separate, and 

 the arteries have attached to them the corpuscles of Malpighi. It is also a noticeable 

 fact that the distinct trunks passing in at the hilum have but few inosculations with each 

 other in the substance of the spleen, so that the organ is divided up into from six to ten 

 vascular compartments. 



The veins join the fine branches of the arteries in the spleen-pulp and pass out of the 

 spleen in the same sheath. They anastomose quite freely in their larger as well as their 

 smaller branches. Their caliber is estimated by Sappey as about twice that of the arte- 

 ries. This author regards the estimates, which have put the caliber of the veins at four or 

 five times that of the arteries, as much exaggerated. The number of veins emerging 

 from the spleen is equal to the number of arteries of supply. 



The lymphatics of the spleen are not numerous. By most anatomists, two sets of 

 vessels have been recognized, the superficial and the deep; but those who have studied 

 the subject practically have found it very difficult to demonstrate the superficial layer. 

 The deep lymphatics have been demonstrated in the capsule of Malpighi, attached to the 

 veins and emerging with them at the hilum. At the hilum, the deep vessels are joined 

 by a few from the surface of the spleen. The vessels, numbering five or six, then pass 

 into small lymphatic glands and empty into the thoracic duct opposite the eleventh or 

 twelfth dorsal vertebra. It was an old idea that the lymphatics were the excretory ducts 

 of the spleen ; but this is a speculation which does not demand discussion at the pres- 

 ent day. 



The nerves of the spleen are derived from the solar plexus. They follow the vessels 

 in their distribution and are enclosed with them in the capsule of Malpighi. They are 

 distributed ultimately in the spleen-pulp, but nothing definite is known of their mode of 

 termination. "We have already referred to the fact that, when these nerves are galvanized, 

 the non- striated muscles in the substance of the spleen are thrown into contraction. 



Some Points in the Chemical Constitution of the Spleen. Very little has been learned 

 with regard to the probable function of the spleen, from the numerous chemical analyses 

 that have been made of its substance. It will therefore be out of place to discuss its 

 chemical constitution very fully, and we shall only refer to certain principles, the exist- 

 ence of which, in the spleen-substance, may be considered as pretty well determined. 

 In the first place, cholesterine has been found to exist in the spleen constantly and in 

 considerable quantity, and the same may be said of uric acid. In addition, chemists 

 have extracted from the substance of the spleen, hypoxanthine, leucine, tyrosine, a 

 peculiar crystallizable substance called, by Scherer, lienine, crystals of hsematoidine, lac- 

 tic acid, acetic acid, butyric acid, inosite, amyloid matter, and some indefinite fatty prin- 

 cjples. It is difficult, however, to say how far some of these principles are formed by 

 the processes employed for their extraction or are due to morbid action ; certainly, physi- 

 ologists have thus far been unable to connect them with any definite views with regard 

 to the probable function of the spleen. 



