; 
: 
43 
birds and most fishes they are oval and flattened, the shape of the 
surfaces varying in different tribes; they have also a nucleus in 
_ them usually of an oval shape; in the reptiles they are oval, very 
large, and comparatively thin with rather hollowed surfaces, with a 
nucleus which projects a little sideways. 
About one in every five hundred of the solid bodies to be found 
in our veins is of altogether a different sort from those of which 
we have been speaking, being globular and colourless ; and while 
the coloured corpuscles are hurrying along in the stream of serum, 
keeping themselves, apparently, as much as possible in the centre, 
our new friend, the colourless corpuscle, loiters along on the 
margin, very often actually touching the sides of the channel, and 
looking, at first like a transparent ball, covered with knobs, 
rolling over and over as it moves. By looking more carefully, 
however, we find that his shape is constantly changing, first 
one part of the surface and then another, being pushed out and 
withdrawn in a curiously undetermined manner. The entire sub- 
stance, indeed, of which he is formed is in a state of perpetual 
unsettlement, flowing and rolling in every conceivable direction. 
Some microscopists describe him as first pushing forward a minute 
feeler or finger into some fine cranny or pore of the body, much 
smaller than himself, and then bringing after the feeler all the rest 
of his mass in the same attenuated way until the opening is com- 
pletely passed, after which the corpuscle regains his original size 
and shape. Sometimes specks of great activity are seen here and 
there inside the corpuscle, and then it begins to grow larger and 
splits into fragments, forming a brood of young corpuscles, each 
exactly like its parent in all its powers and appearances. 
The pale corpuscle is believed to be formed out of the fully 
prepared albuminous material. (Professor Huxley says it probably 
comes from the liver.) It iy in fact a living creature fashioned, in 
some way or other, out of the dead liquid in which it appears, but 
from which it is distinguished, very broadly, by the power of motion 
it contains within itself, the particles of which it is composed 
always dancing, rolling, and falling over each other. Another mark 
of life that it possesses is the power of growth; it increases its 
own substance out of the contributions it receives from the 
materials around it: and yet a third evidence of life is to be seen, 
and it is this: the substance of the life-endowed corpuscle has the 
power of constructing a material which is not alrve, but has been 
_ produced by living operation, and which cannot be produced in any 
other way: this material is known as “‘ formed substance.” It 
seems probable that the fibrin of the blood is itself ‘* formed 
substance” which has been made by the energy of the living 
corpuscles. 
