THE LYMPHATIC SYSTEM. 317 



action on polarized light, were placed at the bottom of a glass vessel, 

 the remainder of which was filled with pure water. The quantity of 

 the substance in solution at any level above or below the plane of con- 

 tact of the two liquids could then be determined by means of a sac- 

 charimeter ; and the examination could be repeated at will without dis- 

 turbing the apparatus. It was found that, under these conditions, dif- 

 fusion took place with readiness only in the immediate vicinity of the 

 contact of the two liquids. Solutions of gum or albumen after 

 several days, had mingled with the water only for a height of one 

 or two centimetres above and below the plane of contact ; and with a 

 concentrated solution of cane sugar, at the end of four weeks the layer 

 of diffusion was only 15 centimetres in thickness. But any mechanical 

 shock or disturbance hastens the process of diffusion and admixture ; 

 and with solutions of gum, sugar, or albumen, a few seconds' agita- 

 tion may produce a uniform mixture which would require an indefinite 

 time by diffusion in a state of rest. 



Absorption and Transudation in the Living 1 Body. 



All the conditions favorable to endosmosis and exosmosis, shown 

 by the above experiments, are present in the living body. The organic 

 tissues and membranes have their normal constitution maintained by 

 the process of nutrition, and exert their special absorptive power on 

 each ingredient of the animal fluids. The extent of absorbing surface 

 is multiplied by the subdivision of the blood-vessels, the glandular 

 tubes, and the anatomical elements of the organs. The fluids are in 

 immediate contact with the absorbing surfaces, at a nearly uniform, 

 moderately elevated temperature ; and the movement of the blood and 

 lymph supplies the requisite ingredients by constant renewal, and inces- 

 santly removes the surplus of transuded material. 



In the living body, accordingly, transudation takes place with great 

 rapidity. It has been shown by Gosselin, that if a watery solution of 

 potassium iodide be dropped on the cornea of a rabbit, the iodine 

 passes into the cornea, aqueous humor, iris, lens, sclerotic and vitreous 

 body, in the course of eleven minutes ; and that it will penetrate the 

 aqueous humor in three minutes, and the substance of the cornea in a 

 minute and a half. In these experiments it is evident that the iodine 

 passes into the deeper portions of the eye by endosmosis, and not by 

 transportation through the blood-vessels ; since it is not 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, and in 

 half an hour 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 on the eye of a cat, produced dilatation and 

 immobility of the pupil in half an hour. The aqueous humor of the 

 affected eye consequently contains atropine, which has been absorbed 



