366 THE LYMPHATIC SYSTEM. 



transported by the bloodvessels ; since no trace of it is to be found in 

 the tissues of the opposite eye, examined at the same time. 



The same observer has shown that the active principle of belladonna 

 penetrates the tissues of the eyeball in a similar manner. He applied a 

 solution of atropine sulphate* to both eyes of two rabbits. Half an hour 

 afterward, the pupils were dilated. Three-quarters of an hour later, the 

 aqueous humor was collected by puncturing the cornea with a trocar ; 

 and this fluid, dropped upon the eye of a cat, produced dilatation and 

 immobility of the pupil in half an hour. These facts show that the 

 aqueous- humor of the affected eye actually contains atropine, which it 

 absorbs from without through the cornea, and which thus acts directly 

 upon the muscular fibres of the iris. 



But in all vascular organs, the processes of endosmosis and exosmosis 

 are still further accelerated by two important conditions, namely, first, 

 the movement of the blood circulating in the vessels, and secondly, the 

 minute dissemination and distribution of these vessels through the 

 tissues. 



If a solution of the extract of nux vomica be injected into the subcu- 

 taneous connective tissue of the hind leg of two rabbits, in one of which 

 the bloodvessels of the limb have been left free, while in the other they 

 have been previously tied, so as to stop the circulation of blood in the 

 part, in the first rabbit the poison will be absorbed and will produce 

 convulsions and death in the course of a few minutes ; but in the second 

 animal, owing to the stoppage of the local circulation, absorption will 

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

 so slowly, that its specific effects will show themselves only at a late 

 period, or even may not be produced at all. 



The processes of exosmosis and endosmosis, therefore, in the living 

 body, are regulated by the same or similar conditions as in artificial 

 experiments ; but they take place with greater rapidity, owing to the 

 movement of the circulating blood, and the extent of contact existing 

 between the bloodvessels and adjacent tissues. Although the arterial 

 blood is everywhere the same in composition, yet its different ingredients 

 are imbibed in varying quantities by the different tissues. And the 

 proportion of each ingredient is determined, in each separate tissue, by 

 its special absorbing or endosmotic power. 



Albumen, under ordinary conditions, is not endosmotic ; that is, it 

 will not pass by transudation through an animal membrane. For this 

 reason, the albumen of the blood, in the natural state of the circulation, 

 is not exuded from the secreting surfaces, but is retained within the 

 vascular system. But the degree of pressure to which a fluid is sub- 

 jected has an influence in determining its endosmotic action. If the 

 pressure upon the blood in the capillary vessels be increased, by ob- 

 struction to the venous current and backward congestion of the capil- 

 laries, then not only the saline and watery parts of the blood pass out 

 in larger quantities, but the albumen itself may transude and infiltrate 

 the neighboring parts. In this way albumen may make its appearance 



