thor gives a definite idea of how the capillaries and tissues operate in 
producing the circulation ;. that they are powerfully instrumental in this 
important function is now generally admitted; the circulation being 
considered due to a “series of vital attractions and repulsions not es- 
sentially different from those which are witnessed in physics and chem- 
_Astry ;” but we have never yet been informed what these attractions and 
spolaiot: are due to. It is on this point that Dr. Draper has noe 
much light. 
_ The physical principle» upon which this new theory is based, is ex- 
plained in the following manner.—If, in a-vessel containing water, a 
tube of small diameter be placed, the water immediately rises to a cer- 
tain point in the tube, and remains suspended. Let the tube be now 
_ broken off below. that point, and replaced in the cup of water ; the li- 
quid rises as before, but though it reaches the broken extremity, it does 
not overfiow. . A capillary tube may raise water to its highest termina 
tion, but'a continuous current cannot take place through it. If, howev- 
(er, the liquid at the top of the tube be allowed to evaporate, it will be 
- ‘Teplaced by that from the vessel, causing in this way a current through 
‘tube; the same is true if the liquid be ignited, as in the case of an 
ordinary lamp, the wick of which draws the oil to the top, where it re- 
mains Stationary until ignited, when it) flows rm" Me elt the wick 
Until the lamp is emptie 
~ Ttis seen from these facts that pedleaey ovis attraction can un- 
seen circumstances determine the continuous flow of a liquid 
fe 'atube. But there is yet another circumstance under which 
this might happen, as where the attraction between the liquid and sides 
of the tube is greater at the ‘point where they first come in contact, 
than farther up. the tube. 
‘Uppose a capillary tube composed of some substance Aneiig a 
’ _ tong attraction for oxygen, to be immersed in an oxydizing liquid, the 
| ¢ ad will enter the tube under strong attraction, but losing its oxygen 
4 iheatedetion diminishes as it passes into the tube, and if the attraction 
between the. first portion of the tube and the liquid remains the same, 
“ this ast will continue to enter and push forward that part that has lost 
re mores for the sides of the tube. ‘The above fact is expressed by 
: hor in the following terms.—If a given liquid occupies a capil- 
¥: tube, or a porous or parenchymatous structure, and has for that 
is senile is. sited: to She: itt sapealbaniin in the following 
~ The arterial blood blood charged with oxygen, penetrates the various 
“means of the capillaries, and as there is a strong: attraction 
: eats Vol. II, No. 5:—Sept., 1846. 36 
