42 
To the naked eye the layer of blood upon slide number one 
appears of a pale reddish colour, quite clear and homogeneous ; 
but on viewing it with a pocket lens, it will look like a mixture of 
excessively fine yellowish-red particles, such as sand or dust, in a 
watery and almost colourless fluid. When the blood is just drawn, 
the particles will be seen scattered very evenly through the fluid, 
but by degrees they flock together into minute patches, and the 
layer becomes more or less spotty. 
. On looking at slide number two, the drop of blood will be found 
unaltered in form, but changed in that it no longer flows, but 
has become a soft moist mass that may be removed from the 
slide with a penknife. This setting, or coagulation, be it ob- 
served, is very different indeed from drying; and, on turning to 
slide number three, you will discover that the salt has prevented 
the coagulation, the blood remaining as fluid as it was when it left 
the body. / 
Let me at once bring before your notice the solid or living 
part of the blood. The fine particles, of which I have spoken 
as being seen under a pocket lens, resolve themselves, under 
the microscope, for the most part into red discs, rather thinner 
in the centre than at the edge, and with a slightly granulated 
surface; in fact, they are in shape more like the domestic 
crumpet, which is sometimes to be found a welcome addition 
to the tea table, than anything else that I know of. They are 
soft and elastic, so that they readily squeeze through apertures 
less than their own breadth, and immediately regain their proper 
shape on getting through. As to the size of these corpuscles, they 
have none to speak of—that is to say, their dimensions are so 
very minute that neither observation nor description can give a 
clear idea of them. About 3,200 of them can be ranged in 
single file in the length of one inch very well; then 3,200 files side 
by side, each file containing its 3,200 corpuscles will give 
10,240,000 corpuscles to form the pavement of cone square inch ; 
but they are lying flat upon the floor, and they will probably be not 
more than one fifth as high as they are broad, so that we may 
imagine 16,000 layers in the height of one inch, all of which gives 
the result of 163,840 millions of corpuscles in one cubic inch. In 
the full grown and healthy human body there are about 15-Ibs. 
of blood,¥of which about 21-lbs. 2-oz. are solid matter or cor- 
puscles, whose total array comes out at about two and a-half 
millions of millions. In other animals than man the corpuscles are 
slightly different, both as regards shape and size ; in the mammals 
generally they are of the crumpet shape, with the surfaces of the 
discs slightly hollowed out ; in the camel tribe, however, they are 
longer than their breadth and without the hollowed surfaces; in 
