VARIOLA AND TYPHUS. 
372 
is an exception to the general rule, while during the course 
of malignant small-pox, whether in man, the sheep, or the swine, 
the absence of these confluent pustules is a circumstance that very 
rarely happens. 
2. The post-mortem examination of men and of quadrupeds 
that have died of variola has, with very few exceptions indeed, 
presented these pustules on the mucous surfaces of both the 
respiratory and intestinal passages, while in four cases alone of 
typhus has the presence of these pustules been observed. 
3. Ordinarily the small-pox comes under observation all at 
once in a certain locality ; and during almost the whole of its con- 
tinuance, whether its character is malignant or mild, one kind 
of eruption only is observed — the pustular one. In the majority 
of cases the typhoid epidemic is always malignant at its first ap- 
pearance, and it is only towards its decline that it assumes a 
milder type; and, instead of a pustular eruption of constant cha- 
racter, exhibits one of four kinds of eruption, and all of them 
terminating well — the pustular, the aphthous, the erysipelatous, 
and the phlegmonous subcutaneous. 
4. These four species of eruption are parcels and portions of 
the mild typhus, while they are only the sad accompaniments of 
malignant variola. 
5. Mild typhus always runs its whole course without erup- 
tion ; but this peculiar eruption is essential to the existence of 
variola. Camper, therefore, has well said, many years ago, that 
the typhoid epizootic differed essentially from the variola and 
the scarlatina of the human being;: to which MM. Girard and 
Dupuy have added, that the pustular eruptions of typhus were 
only those fortunate metastases, or crises, from more important 
organs to the skin, during the period of convalescence. 
The importance of the subject will, perhaps, be received as an 
apology for one or two observations more. Setting aside the 
evident contagious property by means of which variola is pro- 
duced, we are utterly ignorant of the causes which give rise to 
it. Its appearance is usually sudden no fortuitous circum- 
stances prepare for its approach — no period of time is marked 
for its duration ; and, perhaps, never a year has passed in which 
its ravages have not been more or less extensive as regard the hu- 
man being and the quadruped. It is neither possible to predict 
its appearance nor its departure ; and when it arrives, it oftener 
attacks the young subject than the adult or the old. 
Professor Delafond now enters into a train of reasoning which 
we are not disposed to follow, and from which he draws the fol- 
lowing conclusion, — that there is no analogy between the conta- 
gious typhus of cattle and the variolous diseases of either men or 
