512 PHYSIOLOGY CHAP. 



made to breathe pigmented fluids by means of a spray, the 

 pigments penetrate by tiny pores through the epithelial cells of 

 the inucosa (Klein). 



This theory is reinforced by the extraordinary rate at which 

 fluids and also blood are absorbed when injected into the trachea 

 of living animals. Nothnagel found blood -corpuscles in the 

 interstitial lymph spaces of the lungs barely 3-5 minutes after 

 injection. 



II. The lymph contained in the lymphatic system, as briefly 

 described above, comes from three different sources : 



() The blood, which, by the network of blood capillaries to 

 the various tissues, constantly pours into the lymph spaces the 

 materials required for the nutrition of the tissue cells. 



(5) The living elements of the tissues, which continually give 

 off to the same system, both the products of their synthetic or 

 anabolic processes, destined for use by other tissues and organs, 

 and the products of their analytic or katabolic processes, destined 

 to be eliminated from the body. 



(c) The food-stuffs introduced, and more or less modified or 

 digested in the alimentary canal, known as a whole by the name 

 of chyle, which is periodically absorbed by the lymphatic roots of 

 the intestinal villi. On the strength of this threefold origin we 

 may theoretically distinguish between blood lymph, tissue lymph, 

 and lymph of the digestive apparatus or chyle. Leaving aside for 

 the moment the chyle, the formation and absorption of which will 

 be discussed elsewhere, we will consider the constituents of lymph 

 properly so-called (of the blood and tissues), which is constantly 

 being formed and poured out into the lymphatic lacunar spaces. 

 Since the demand for nutritive materials in the different tissues 

 and organs is quantitatively and qualitatively very different, and 

 since, on the other hand, each tissue and organ is the seat of 

 specific anabolic and katabolic processes, it follows necessarily that 

 the lymph in the lacunar system of the different organs must 

 differ in consistency and composition. 



Up to the present, however, we possess very few analytical 

 data in regard to the differences presented by the lymph coming 

 from the different organs, nearly all these differences being much 

 attenuated, or even obliterated, in the lymph collected from the 

 larger vessels, into which alone it is possible to introduce a 

 cannula. In examining the general characters and chemical 

 composition of lymph, it is almost always collected, as it flows, 

 from a cannula introduced into the thoracic duct of a fasting dog, 

 which yields the whole of the chemical constituents from the 

 several lymphs (coming by the lymphatic channels to the different 

 tissues of the organs) that have not been consumed by the tissues, 

 nor absorbed by the blood-vessels. In collecting lymph from 

 animals of small bulk (rabbits, cats, etc.) the thoracic fistula 



