Foot-and- Mouth Disease. 
457 
molecules, escape. Under favourable circumstances the healing 
process advances rapidly, the abraded surface is covered vf'\\h a 
yellowish mass of exudation, which is ultimately condensed to 
form the epithelial covering. This yellow mass has been 
examined by the microscope, and found to consist of epithelial 
cells, which are represented in the next figure. 
No. 2. 
Microscopic appearance of yellow mass on the surface of a healing abrasion, after the rupture of a 
vesicle. Magnified 400 diameters. 
When the disease is fully developed, all the secretions con- 
tain morbid elements, but, rather curiously, the saliva, which is 
the fluid most capable of conveying the disease, shows the least 
evidence of change ; when obtained as free as possible from the 
mucus secreted by the glands of the membrane lining the cavity 
of the mouth, it is quite pellucid, and contains minute bodies, 
which move with rapidity, these are sometimes found in consider- 
able quantities, and in many specimens bacteria and vibriones 
are also detected, similar in form and character to those which are 
depicted in the illustration No. 3, page 459, as they occur in 
the milk of diseased animals. 
