ON 



THE PHENOMENA 



ACCOMPANYING 



THE MIXTURE OF TWO LIQUIDS 



SEPARATED BY 



A MEMBRANE. 



THE constituents of the food, which have assumed a soluble form in the alimentary 

 canal, are thereby endowed with the property of yielding to the influence of every 

 cause which, in acting on them, tends to change their place or the position which 

 they occupy.* They are conveyed into the blood vessels, and from thence are 

 distributed to all parts of the body. 



The movement and distribution of these fluids, and of all the substances dissolved 

 in them, exclusive of the mechanical cause of the contraction of the heart, by 

 which the circulation of the blood is effected, depend, 1, on the permeability of the 

 walls of all vessels to these fluids ; 2, on the pressure of the atmosphere ; and 3, 

 on the chemical attraction which the various fluids of the body exert on each other.t 

 The motion of all fluids in the body is effected by means of water : and all parts 

 of the animal system contain, in the normal state, a certain amount of water. 



Animal membranes, tendons, muscular fibres, cartilaginous ligaments, the yellow 

 ligaments of the vertebral column, the cornea, transparent and opaque, &c., all 

 contain, in the fresh state, more than half their weight of water, which they lose, 

 more or less completely, in dry air.J 



On the presence of this water depend several of their physical properties. 

 The fresh, opaque, milk-white cartilagesof the ear become, when dried, translucent, 

 and acquire a reddish yellow color. Tendons, when fresh, are in a high degree 

 flexible and elastic and possess a silky lustre, which they lose when dried. By the 

 same loss of water they become, further, hard, horny, and translucent, and when 

 bent, split into whitish bundles of fibres. The sclerotic coat is milk-white when 

 fresh, and becomes transparent by desiccation. 



When these substances, after having lost, by drying, a part of the properties 

 which they possess in the fresh state, are again placed in contact with pure water, 

 they take up, in 24 hours, the whole original amount of water, and recover per- 

 fectly those properties which they had lost. The opaque cornea, or sclerotic coat, 

 which had become transparent by desiccation, again becomes milk-white, while the 

 transparent cornea, which had been rendered opaque by drying, now becomes 

 again transparent. The tendons, which, when dried, had become horny, hard, 

 and translucent, now again become flexible and elastic, and recover their silky 



* The food becomes soluble, and the fluids of the body are sent to all parts. 

 tGeneral causes of their moti>n. J Relation of animal tissues to water. 



3 (9) 



