DIPHTHERIA IN FOWLS 489 
In fowls that die, the exudates are for the greater part in the 
advanced stage, although fatal cases occur in which the lesions are 
restricted to an abnormal quantity of a serous or muco-purulent, more 
or less viscid, exudate in the conjunctiva or nasal cavities. The best 
illustration of the diphtheritic process is found in fowls killed for 
examination in the second stage of the disease. The distribution of 
the lesions shows that the conjunctiva is most frequently affected. 
The exudate in the nasal cavities is in some cases undoubtedly the 
result of the coagulation of the liquid which has passed during the 
course of the first stage from the conjunctiva through the lachrymal 
duct into the nares. In certain cases, how- 
ever, the lesions appear in the nares primarily. 
In some cases the exudate appears in the larynx 
and extends down into the trachea. In these 
cases the fowls are liable to die from suffo- 
cation. Jt occasionally happens that the 
lesions are restricted to the larynx and as the 
fowls die suddenly the cause of death is not 
suspected. Sections of the exudate with sub- 
jacent tissues from the cornea and the mouth 
show that there is a cell infiltration into the 
mucosa which destroys the epithelial layer 
and frequently the submucous tissues to a 
considerable depth. 
The fact should not be overlooked that the 
disease in the eye is usually confined to the 
conjunctiva and the cornea, the posterior por- ee 
. igo Fig. 114. A DRAWING 
tion remaining apparently normal. SHOWING AREAS OF DIPH: 
Mack in his work on thirty-three cases THERITIC EXUDATE IN 
found 40 per cent. had lesions in the con- Derren ener a 
junctiva; in 44 per cent. the nasal mucosa was affected; in 41 
per cent. the mouth was involved and in 33 per cent. the suborbital 
sinuses were distended with exudates. 
From the observations thus far made the provisional theory is 
entertained that the three forms of the exudate—serous or muco- 
purulent, diphtheritic and sloughed mass—represent three stages in 
the course of the same disease. It is easily understood that fowls 
examined in the first stage would be said to be affected with a catarrh 
of the mucosz of the eyes or nares. It is highly probable that in 
many cases the disease never reaches the second stage and if these 
