PERMEABLE TO ALL LIQUIDS. 15 



The permeability of animal tissues to liquids of Animal tis- 

 every kind, and the miscibility of the absorbed permeable 

 liquids with others which are brought in contact ^r^kfndt 

 with the tissues, may be demonstrated by the sim- 

 plest experiments. 



If we moisten one side of a thin membrane with 

 ferrocyanide of potassium, and the opposite side 

 with chloride of iron in solution, we perceive in the 

 substance of the membrane a spot of Prussian blue 

 immediately deposited. (Jon. MULLER.) 



All fluids which, when brought together, suffer a which act 



. .1 .on each 



change in their nature or in their properties, ex- other in the 

 hibit, when only separated by an animal membrane, O f the tis- 

 exactly analogous results ; they mix in the pores of s 

 the membrane, and the decomposition commences 

 in its substance. 



If we tie up one end of a cylindrical glass tube 

 with bladder, and fill it to the height of 3 or 4 

 inches with water or strong brine, neither the water 

 nor the brine flows out through the pores of the 

 bladder under this slight pressure. 



But if we leave the tube containing brine ex- Deposition 

 posed to evaporation in the air, the side of the 

 bladder exposed to the air is soon covered with 

 crystals of salt, which gradually increase, so as to form 

 a thick crust. It is obvious that the pores of the 

 bladder become filled with brine ; that, on the side 

 exposed to the air, the water evaporates ; its place 

 is supplied by fresh brine, and the dissolved salt is 

 deposited, at the external minute openings of the 



