SHEEP DISEASES : CAUSES, NATURE AND PREVENTION. 207 
food foi i espiration and tlie production of heat by oxidation is 
supplied. 
The so-called solids of the blood consist of little bodies, known 
as cells 01 corpuscles; and inasmuch as some of these are colorless, 
while others, when in bulk, are of a red color, they are distin¬ 
guished respectively as white (leucocytes) and red cells. The 
former of these are the larger, and they are endowed with the 
power of motion in a limited degree and of actively altering their 
shape. The latter are much smaller and are practically devoid 
of the power of motion ; they are believed to be the highest stage 
in the development of the white cells. 
Both these bodies are absolutely necessary in the blood, and 
to the white cells is now ascribed a function which, until recently, 
was only suspected, viz., the function of destroying injurious 
organisms, such as the germs of disease—devouring them, in fact_ 
and of removing dead matter from the tissues; they are the scav¬ 
engers of the system, and are as voracious as jelly-fish, closing 
over the object of their attack and digesting it, or all of it that is 
capable of being digested, and ejecting the remainder into the 
blood stream. By their agency, too, the solid parts of the blood 
—even the red cells—are removed from the tissues when that 
fluid is poured out into them as the result of an injury or in con¬ 
sequence of disease. If, in other words, an individual is unfortu¬ 
nate enough to get a “black eye,” these little bodies set to work 
and, by breaking up and removing the red cells, upon which the 
color of the bruise is dependent, they restore the damaged tis¬ 
sues to their original condition. Moreover, the white cells rush 
into the breach whenever a wound is inflicted, and not only pre¬ 
serve the exposed tissues from the action of injurious organisms, 
but supply all the means by which the breach is filled up. 
The red cells have equally as important, and even more im¬ 
portant, an office to fulfill. They are the means by which oxygen 
is carried to the tissues for the purpose of oxygenation or decar 
bonization. They are, in other words, the conveyancing media 
of the gas (oxygen) necessary for the purpose of burning up the 
excess of hydrocarbons and carbohydrates, thus getting rid, to a 
large extent, of effete and injurious material, and of keeping np 
