270 THE Microscopr. 
cells are capable of taking some of the same pabulum and con- 
pad. verting it it into nerve nuclei and thence into 
(ee : ) nerve formed materia]. Thus, man, a federation 
ess of these cells, is capable of converting his food in- 
es to materials like his own body, hair, nails, skin, 
ge): etc., while the dog by eating of the same food will 
_ convert it into its own peculiar tissues. The 
Ce) youngest, most recently deposited matter of a tis- 
sue is found in its nuclei, the oldest in its formed 
(@) material. There is a law in the body by which 
the amount of pabulum supplied to the nuclei by 
the blood, just equals the wear and waste of the 
© cells. But if from any cause the part be irritated, 
&) be spurred to increased action, then an extra 
amount of blood flows to the part, an extra amount 
Hustratingai- Of Dabulum is furnished to the germinal matter, 
minishing nU- causing it to increase rapidly. Now from two to 
Pee ere Se five nuclei are seen in one cell. If the process 
goes on the changes become so rapid that the germinal matter 
does not change into formed material, and there now appear a 
multitude of round, globular bodies, in cells, and on the surface 
of cells, familiarly known as pus. Doubtless some of these pus 
cells are the migrated white corpuscles of the blood, but the 
mags of them represent living germinal mat- 
ter undergoing rapid changes and possessed 
of a low vitality. This germinal matter may 
come from an irritated cell. It must be 
borne in mind that the supply and change 
of pabulum to the germinal matter, and from Fig. 6. 
it to the formed material of the body are ous in epithelial 
constant and uninterrupted. From what x 250 
has been said it must be evident that compared to human life, 
the life of any one cell is extremely short. 
When we consider the immense numbers of cells removed 
daily from the surface of the body by the friction of clothing— 
laying aside the work of the sponge and towel—some idea can 
be gained how active must be the changes going on just beneath 
the surface. Add to this the number rubbed off by every act of 
moving the tongue, in speaking, drinking, and eating, and we 
ipo. 
