PHYSIOLOGY OF THE CIRCULATION. 99 



of fluid through the minute pores of several layers 

 of membrane would otherwise have added materially 

 to the tedious character of the observation. It may 

 also be observed, that this enlargement of the pores 

 facilitated exudation quite as much as absorption ; 

 and in the living body the passage of fluids through 

 the coats of the small blood-vessels is greatly pro- 

 moted by their extreme tenuity, by the high tempe- 

 rature, and possibly by other favourable conditions. 



The apparatus being thus arranged, a measured 

 quantity of liquid was poured into the glass vessel, 

 so as to reach nearly to the commencement of the 

 short arm of the syphon, and a column of water, 

 varying from three to five inches in height, was 

 maintained in the membranous reservoir. It will be 

 seen by a glance at the accompanying diagram that 

 the fluid, after entering the first glass tube, and 

 ascending from its curved portion, would then 

 pass through the membranous tube, and reaching the 

 short arm of the syphon, be finally discharged on 

 the exterior of the vessel containing the stagnant 

 fluid. 



During its passage through the membranous tube, 

 the stream was, by means of the lateral openings 

 existing in the latter, enabled to communicate with 

 the external stagnant liquid. 



The calibre of the arched portion of the first glass 

 tube had been considerably diminished by the flat- 

 tening of the tube during the process of bending it ; 

 so that the stream escaping from it into the mem- 

 branous tube was necessarily much less than one- 

 fourth of an inch in diameter. But even this dis- 



H 2 



