LYMPHATIC SYSTEM. 149 



accompany. From this receptaculum likewise (besides the 

 trunk already mentioned which goes to the right side) arise two 

 other trunks pretty equal in size, one of which runs upon the 

 left side and the other upon the right side of the left aorta, till 

 they come within two or three inches of the left subclavian vein, 

 where they join behind the aorta, and form a number of branches, 

 which are afterwards joined by the lymphatics of the left side of 

 the neck, so that here a network or plexus is formed, as upon the 

 right side. From this plexus a branch issues, which opens 

 into the angle between the jugular and the lower part or trunk 

 of the subclavian vein. In these networks, formed by the 

 lymphatics near their terminations in the veins, this system in 

 the turtle likewise differs remarkably from that in birds. 



So much for the general description of the lymphatic system 

 in this animal. I shall next add what I have remarked as to 

 the more minute distribution of its lacteals. In the first 

 place, it may be observed that what knowledge we have of the 

 minute distribution of those vessels in quadrupeds has been 

 acquired from examining them when filled with their natural 

 fluid, the chyle; for the valves with which those vessels abound 

 prevent our injecting their smaller branches, as we do those of 

 the arteries and veins of the intestines. But in this animal I 

 have been so fortunate as to force the valves, and to inject the 

 lacteals from their trunks to their branches, so as to fill them 

 all around with quicksilver, in several parts of the intestine. 

 In these experiments I observed that the quicksilver was often 

 stopped by the valves, where the lacteals run upon the mesen- 

 tery, or where they are just leaving the intestine ; but when 

 those valves were forced, and the quicksilver had once got 

 upon the surface of the gut, it generally ran forward without 

 seeming to meet with any obstacle. The lacteals anastomose 

 upon the intestines, so that the quicksilver, which has got 

 upon them by one vessel, in general, returns by another, at 

 some distance. The larger lacteals, which run upon the intes- 

 tines, accompany the blood-vessels; but the smaller lacteals 

 neither accompany those vessels nor pass in the same direction, 

 but run longitudinally upon the gut, and dip down through the 

 muscular coat into the cellular or nervous, as it has been called, 

 which in this animal is very thin in comparison to what it is in 

 the human subject. So far I have traced those vessels to my satis- 



