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Six days. A loss of substance is evident at the center of the roughened area. 
The conjunctival discharge and the photophobia persist. 
Seven days. The superficial loss of corneal substance has increased, otherwise 
the condition remains the same. 
Fight days. Animal chloroformed. There is considerable cedema of the lids 
with a watery discharge. The eroded area has increased in extent. Tissues 
preserved for histological study. 
Histological examination.—The epithelium covering the central portion of the 
corneal surface is very thin and consists of only two layers of cells. There is 
deficiency of epithelium over an area not over 0.5 millimeters across. Cytoryctes 
are present in considerable numbers in a single area of the epithelium. 
SUMMARY. 
The inoculation of the monkey’s cornea with vaccine virus, provided a 
secondary pyogenic infection does not supervene, results in the produc- 
tion of a lesion which has rather indefinite macroscopic characters. 
Twenty-four hours after the inoculation a slight roughening, associated 
with more or less elevation of the corneal epithelium, may be apparent. 
After 48 hours a loss of epithelium about the point of inoculation is 
frequently present. The further development of the lesion is associated 
with an increase in this erosion and with the development of some degree 
of photophobia and a conjunctival discharge. 
‘The histological characters of the lesion are as follows: 
In the corneas taken 17 and 24 hours after vaccination the defect pro- 
duced by the inoculation trauma is filled in by the growth of the epithe- 
lium. This constitutes the ordinary form of repair following simple 
incision of the cornea. Cytoplasmic forms of Cytoryctes are present in 
the epithelium. Subsequent to this, up to 8 days and probably for an 
indefinite period, there is a loss of epithelium over an area surrounding 
the site of the inoculation. The epithelium is thin and tapers at the 
edge of the abraded area, and here the cells appear to be undergoing de- 
generation. Cytoryctes are present in all lesions. Leucocytes apparently 
play no part in the process but are present in those lesions in which there 
is injury to corneal connective tissue. 
The destruction of epithelium evidently outstrips the <csuawhaat of the 
epithelium in the corneal vaccine lesions of the monkey. 
DISCUSSION. 
When we compare the lesion produced on the cornea of the monkey by 
inoculation with vaccine virus with that which follows a similar inocula- 
tion on the rabbit, we see that, although the fundamental characters of 
the lesion are the same, there are important differences. 
One of the striking features of the vaccine process on the monkey’s 
cornea is the loss of epithelium about the line of inoculation. ‘This loss 
is apparent in the early as well as in the more advanced stages of the 
process and probably persists until the active stages are passed. It is 
evident that the vaccine virus in these experiments produced a more ex- 
tensive destruction of corneal epithelium than has been observed in the 
