Royal Society. 53 



animal mechanism. The grand organs of absorption the author 

 believes to be the veins ; and a principal object of his paper is to 

 point out the mode in which they acquire this remarkable faculty. 

 The principal condition which this faculty of imbibition implies, is 

 a difference in density between the contents of the vessels which are 

 to absorb, and the contents of those which furnish the matter to be 

 absorbed. If the several constituent materials of the body, both fluid 

 and solid, were to remain in the same unaltered state, both chemi- 

 cally and physically, there could be no interchange among them : 

 in order that mutual penetration may take place between two ele- 

 ments, the one must differ from the other : that which is designed 

 to absorb must be, with relation to that which is to be absorbed, 

 more dense ; that is, must contain a smaller quantity of water in 

 proportion to its solid ingredients. For the continuance of the de- 

 licate processes concerned in the access and removal of the nutrient 

 fluids, it is necessary that a difference should be established be- 

 tween the arterial and the venous blood in respect of density. This 

 purpose the author conceives is accomplished by the abstraction from 

 the former of a portion of its water by the sudoriparous glands of the 

 skin on the one hand, and by the lymphatic vessels on the other. 



That the separation of the lymph from the blood is calculated to 

 increase its density, is proved by its chemical analysis ; lymph con- 

 taining from 96 to 97 per cent, of water, and blood from 77 to 82 

 per cent. The author regards this separation of lymph from the 

 blood as the result of a purely vital process of the same nature 

 as that by which the saliva and the watery portion of the urine are 

 secreted from the circulating mass. He considers that his views are 

 supported by the anatomical distribution of the lymphatic system : 

 for, on the principle that organs are found in the vicinity of the 

 places whei - e their office is wanted, the office[of the lymphatics must 

 be general, inasmuch as the system is general. These vessels may, 

 in fact, be regarded as the essential element of an universally dis- 

 tributed gland. The mode in which the lymphatics are finally con- 

 nected with the blood-vessels appears also to indicate that the object 

 in view is to keep their watery fluid separate from the blood as long 

 as possible ; for, as is well known, they do not transfer their contents 

 into the neighbouring veins, but pour their whole fluid into the 

 superior vena cava at the moment it is about to enter into the 

 heart. 



The remarkable manner in which the lymphatic system is de- 

 veloped in some of the lower tribes of animals, whose bodies are en- 

 cased in an impervious horny covering, such as turtles, lizards and 

 serpents, is adduced in further corroboration of the author's views. 

 He regards the serous membranes as contrivances for the accom- 

 modation of a great number of lymphatics ; and the intimate con- 

 nexion which the function of these vessels has with the life and 

 nutrition of internal organs he thinks is shown by the remarkable 

 amount of disturbance consequent on inflammation, or other morbid 

 condition of serous membranes. Finally, the author adverts to the 

 influence which the difference of endosmotic capability engendered 



