318 FUNCTIONS OF NUTRITION. 



through tine cornea, and acts directly on the muscular fibres of the 

 iris. 



But in all vascular organs, endosmosis and exosmosis are further 

 accelerated by the movement of the blood. 



If a solution of nux vomica be injected into the subcutaneous con- 

 nective tissue of the hind leg of two rabbits, in one of which the local 

 circulation is unimpeded, while in the other it has been arrested 

 by ligature of the blood-vessels of the limb, in the first animal the 

 poison will be absorbed with sufficient rapidity to produce its specific 

 effects in a few minutes ; but in the second, absorption will be 

 retarded, and the poison will find its way into the general circulation 

 so slowly, that its action will be manifested only at a late period, or 

 even not at all. 



Albumen, under ordinary conditions, is but very slightly endosmotic 

 or diffusible; while peptone possesses these properties in a marked 

 degree. Peptone, accordingly, after its production by the digestive pro- 

 cess, is readily absorbed from the intestine and enters the blood-vessels ; 

 but the albumen of the blood, in the normal state of the circulation, is 

 not exuded from the secreting surfaces. If the pressure, however, within 

 the capillary vessels be increased by venous obstruction, not only the 

 saline and watery parts of the blood pass out in larger quantities, 

 but the albumen also transudes and infiltrates the neighboring parts. 

 In this way albumen may make its appearance in the urine, from dis- 

 turbance of the renal circulation; and local oedema or general ana- 

 sarca may follow upon venous congestion in particular regions or at 

 the centre of the circulation. 



The Lymph and Chyle. 



The lymph is the fluid which, having been absorbed from the various 

 tissues and organs of the body, is transported by the lymphatic vessels 

 and discharged into the great veins near the heart. As the chyle is 

 simply the fluid of the mesenteric lymphatics, which has become white 

 and opaque, from the absorption of digested fat, it is properly studied 

 at the same time with the lymph in general. Lymph may be obtained 

 from the living animal by introducing a canula into the thoracic duct 

 at the root of the neck, or into the lymphatic trunks in other regions. 

 It was collected by Rees from the lacteals of the mesentery and from 

 the lymphatics of the leg in the ass, by Colin from the lacteals and 

 thoracic duct of the ox, and from the lymphatics of the neck in the 

 horse. We have obtained it from the thoracic duct in both the dog 

 and the goat. 



Physical Characters and Composition of Lymph. The lymph, as 

 obtained from the thoracic duct in the intervals of digestion, is an 

 opalescent or nearly transparent, alkaline fluid, usually of a light amber 

 color, and having a specific gravity of 1022. Its analysis shows a close 

 resemblance in composition with the plasma of the blood. It contains 

 water, fibrinogen, albumen, fatty matters, and the usual saline sub- 



