OF THE SPLEEN. 271 



in the lymphatic glands, that a tolerably accurate idea of them 

 may be obtained by referring to Plate VIII, fig. 4. The ulti- 

 mate branches of the arteries and veins are so distributed as 

 to form a most beautiful network of blood-vessels upon each 

 particular cell, and we shall render it probable that the ex- 

 treme branches of the arteries form a secretion into these cells. 

 SECT. 66. Mr. Hewson, in the beginning of his inquiries 

 after the excretory duct of the spleen, was not more successful 

 than his predecessors had been ; but having observed that the 

 lymphatic vessels were the excretory ducts of the lymphatic 

 glands, and also that the lymphatic vessels of the thymus per- 

 formed the office of an excretory duct to that gland, he was 

 led, from this circumstance, to conjecture that the great num- 

 ber of lymphatic vessels found in the spleen might possibly be 

 intended to return the secreted fluid from it, and thereby be- 

 come in effect its excretory duct. In order to discover if his 

 conjectures were well founded, the following experiments were 

 made. 



EXPERIMENT I. 



SECT. 67. A dog was opened alive, and after a ligature had 

 been passed round the splenic vessels, the whole spleen was cut 

 out. 



SECT. 68. On examination of the lymphatic vessels upon the 

 surface of the spleen, they were found very turgid, and the 

 fluid contained in them appeared of a much darker colour than 

 he had observed in any other lymphatic vessels ; on puncturing 

 one of the largest of these vessels, a small quantity of the fluid 

 it contained was received into a teacup, which was red, and 

 coagulated soon after being exposed to the air. 



SECT. 69. Mr. Hewson soon discovered that a dog was an 

 unfavorable subject on which to make this experiment com- 

 pletely; because, in that animal, the splenic blood-vessels, both 

 arteries and veins, are divided into many branches, which enter 

 the spleen at some considerable distance from each other; 

 therefore the following experiment was made. 



EXPERIMENT II. 



SECT. 70. As soon as a bullock was killed, and the abdo- 

 men opened, a ligature was passed round the splenic vessels 



