270 SITUATION AND STRUCTURE 



chosen on which to demonstrate the lymphatic vessels; and 

 they are also as numerous in the internal substance as on the 

 external surface, which we can prove in fish, whose lymphatic 

 vessels are without valves, so that we can inject them from 

 trunk to branch. Now if we fill the lymphatic vessels coming 

 from the spleen of a fish with a red injection, we can colour 

 the gland as highly as if it had been injected by the artery or 

 vein ; hence it is evident that the lymphatics are coextended 

 with the blood-vessels to all parts of this gland. 



SECT. 61. In the human body the lymphatic vessels pass 

 through some lymphatic glands which are situated near the 

 sinuosity of the spleen, from whence they pass on towards the 

 thoracic duct, into which they empty themselves. 



SECT. 62. The nerves inservient to the spleen are branches 

 from the par vagum and intercostal nerves, which form a plexus 

 called the splenic; these enter the sinuosity with the blood- 

 vessels, and attend them through their minutest ramifications. 



SECT. 63. Thus we have shown that the spleen is extremely 

 vascular ; insomuch that when injected it appears a mere con- 

 geries of vessels, and that the quantity of blood circulating 

 through it is very considerable. 



SECT. 64. In section 56 we said, that there are cells in the 

 spleen, but not of the kind commonly supposed to have been 

 demonstrated in spleens prepared as there described ; but 

 although we deny the existence of such large cells, (which are 

 no other than what may be called the skeleton of a spleen, 

 made by destroying its minute structure,) yet we assert that 

 there are innumerable cells dispersed throughout the whole 

 substance of the spleen, but they are so very small as not to 

 be discovered without the aid of a microscope : these may be 

 seen in the following manner. 



SECT. 65. Take a small thin piece of a spleen that has been 

 minutely injected, (i. e. the arteries and veins completely filled 

 with a coloured injection,) steep it a day in clean water, chang- 

 ing the water frequently; upon examination of this with a lens 

 j^ of an inch focus, an almost infinite number of cells may be 

 distinctly seen, the round figure of which, as well as their great 

 regularity, sufficiently distinguishes them from the irregular 

 interstices of the reticular substance. The size and shape of 

 these cells so nearly resemble those we have before described 



