FORCE WITH WHICH GASES AND LIQUIDS PASS THROUGH CELLULAR TISSUE. 43 



force, and we judge from the phenomena of their nodal lines, when they are thrown 

 into vibration, that their elasticity varies in different parts ; yet the mere fact of their 

 permanence assures us that they are in a state of stable equilibrium. On the other 

 hand, organized structures are in a condition of instable equilibrium, and require a con- 

 tinued series of adjustments for the perpetuation of their existence. In the crystal, the 

 electrical or polar forces have compensated one another, and its particles being brought 

 iuto a state of rest, continue so without change; while in the living being their situation 

 is only momentary; they are subject to incessant vicissitude and change; their place 

 has to be supplied by new material ; and to accomplish this end, electrical currents 

 traverse the body in all directions, and machinery more or less complex is employed 

 to bring new matter and carry the effete away. 



137. Does this cellular or areolar structure, which appears to be the essential habitat 

 of vitality, owe its properties to the residence of a peculiar force, or are they derived 

 from its organization I If the latter, we ought to find it possessed of remarkable char- 

 acteristics, of forces arising from the aggregation of particles. 



138. It has been known for some years that gases and liquids pass through porous 

 structures with a considerable force. If over the mouth of a cylindrical jar a thin sheet 

 of India-rubber is tied, and the jar exposed to an atmosphere of ammonia or pro- 

 toxide of nitrogen, in the course of a short time, by the ingress of a portion of the ex- 

 ternal atmosphere, a pressure is created tending to rupture the membrane outward. 



139. That the force exerted in this case is very great, appears from the following 

 experiment : In a cylindrical jar, abed (_fig. 17), four inches long, and one and a quarter 

 in diameter, a siphon gauge, <?, was placed, and over the mouth of the jar a piece of In- 

 dia-rubber fortified by a layer of stout cloth was tied. Two pieces of tape, crossing each 

 other at the top and passing down the sides of the jar, were knotted as tightly as possible 

 at its bottom, and the arrangement was then exposed to an atmosphere of ammonia. 

 In the course of six hours, the India-rubber, notwithstanding it was forcibly held down 

 by the cloth and tapes, began to stretch upward, and the gauge had risen thirteen divisions 

 of an arbitrary scale attached to it. In twenty-four hours it had risen to nineteen and 

 a half, and, finally, to twenty, after which k remained stationary. On estimating the 

 divisions of the scale, after the experiment was over, it was found that the maximum 

 pressure in this case was about two thirds of an atmosphere, or ten pounds on the 

 square inch. 



140. This effect is not confined to gases, but takes place with equal energy when 

 liquids only are used. In a jar containing alcohol, a gauge was placed, and a piece of 

 human peritoneum was stretched over the mouth, fortified by silk. The whole was 

 then sunk into a vessel of water. In twelve hours it was found that the level of the 

 fluid in the gauge had risen the whole length of the scale, and that when the maximum 

 pressure took effect, the gauge was exhibiting a condensation of one atmosphere exactly. 



141. Here, then, we have proof that the passage through tissues is accomplished 

 with a degree of energy indicating that the forces which produce it are of a very high 

 intensity. To measure these forces, or to obtain some approximation of their value, 

 the following researches were made. 



