SHEA AND LAWSON, ON POPULAR PHYSIOLOGY. 293 
“ The quantity of blood in the body.—The precise determination of this 
point is difficult. It has been found that if numerous vessels in the body 
of an animal are opened, and the blood permitted to pour from them, a 
TD 
Piles or rouleaus of red corpus- 
cles, exhibiting a peculiar ten- 
dency that these corpuscles pos- Blood-corpuscles: a and 4, the two different 
sess of running together and ad- appearances of red corpuscles. 
hering by their broad surfaces. 
large quantity can be collected. In this manner it has been estimated 
that the weight of the blood is to that of the body: 
As 1 to 12 im an ox. 
» Ll to 18 ina horse. 
,, 1 to 16 ina dog. 
These data can only be an approximation to the truth; for however 
freely the vessels are opened and the blood permitted to flow, still a large 
quantity must remain in the body. Nor can such an experiment be 
made on the human subject, except, indeed, in cases of execution. It is 
stated that as much as 24 lbs. of blood were taken from a decapitated 
female. Applying the results of experiments on other animals to the 
human body, it appears that the amount of blood contained may be 
estimated at 18 lbs. to 20 lbs.” 
We now give an extract from Dr. Lawson’s account of the 
cilia : 
“The larger bronchial tubes are lined on the inside by a beautiful deli- 
cate down, soft as velvet, of which I have just placed a portion under 
the microscope ; and what a pretty sight is presented—a field of corn in 
miniature! This down is formed by an almost infinite number of ex- 
tremely minute, hair-like filaments, resting on club-shaped projections, 
e 2 
° rite acme Ae AON. 
SS 3 ° fe 
Sosy ac 26 08 Get one heed 
DO Sawa esis ° e 
Fig. 40.—A portion of the ling membrane of the 
Windpipe, showing the Cilia. a, the club-shaped cells; 
b, particles of matter; c, the Cilia—The arrows indicate 
the direction of the currents. 
and perpetually moving in one direction, giving exactly that appearance 
to the eye which is produced by a meadow swayed in gentle undulating 
curves by the action of the wind (vide fig. 40). I now drop a small 
