40 
Dr. BealEj on the Red Blood-corpuscle, 
of epithelium, cartilage, fibrous tissue, muscle, or nerve, 
consists almost entirely of germinal matter, and during this 
period of existence it grows and divides into smaller portions, 
and this process of multiplication is determined simply 
by the quantity of pabulum present (PI. YII, figs. 11, 15). 
These colourless masses of germinal matter are the so-called 
white blood-corpuscles. Many are, however, much smaller 
than usually described. Much of the pabulum present having 
thus been converted into masses of living matter, the process 
of division and subdivision ceases. Each mass continues to 
grow, but more slowly than before, and its outer part be- 
comes resolved into formed material. This matter con- 
tinues to be formed, and accumulates around the corpuscle 
(figs. 12, 13, 16, 19, 21, 22). 
The relative proportion of germinal matter to formed ma- 
terial, just as in other cells or elementary parts, is difierent 
in corpuscles of diflPerent ages, and the refractive power of the 
formed material of different discs varies greatly (see figs. 11 
to 25). The refraction of the corpuscle may so nearly coin- 
cide with that of the serum, that the outline of the corpuscle 
is only visible if great precautions are taken in illumination. 
In the nutrition of the blood-corpuscle, I conceive, pabulum 
passes through the outer coloured portion into the germinal 
matter, where it acquires the same vital powers which the 
germinal matter already existing, possesses. The latter is 
gradually resolved into the coloured material. This coloured 
viscid matter in the physical condition of colloidal substance, 
being slowly combined with more water, is dissolved out 
from the changing mass and gradually converted into excre- 
mentitious substances, such as carbonic acid, urea, &c., and 
substances which take part in the nutrition of the tissues. If, 
however, the red colloidal matter lose water, it passes at 
once into the crystalline condition. This conversion of 
living matter into colloid, and the latter into a crystalline 
substance, is a most interesting fact.*^ 
When blood becomes stationary, as in a capillary vessel, or 
extravasated in a tissue, the red corpuscles soon undergo 
change. Sometimes blood-crystals soon form. In other cases 
the haemato-crystallin becomes concentrated, and coloured 
granules of no definite form are all that remain of the red 
corpuscles. But under these circumstances the white corpus- 
cles and the nuclei of the nucleated red blood-corpuscles in- 
crease in size. Nutrient pabulum is necessarily absorbed 
more rapidly by the germinal or living matter when stationary, 
* Professor Graham divides substances into colloids and crystalloids. 
See ' Pliil. Trans./ 1861, page 183. 
