19

to draw attention to one or two questions which have appeared during the course
of the investigation.

      In the first place, it is important to note the great differences in the agglu-
tination value of the sera in the different cases. A complete reaction in some
cases was obtained in no higher dilution than 1 in 40, while in other cases a
complete reaction was observed in a dilution of 1 in 1200 or even higher. The
significance of these variations has been already pointed out by Birt and Lamb¹³
and by Bassett-Smith. ¹⁴

      In the second place, it is of interest to note that M. Melitensis was iso-
lated from the spleen at various stages of the disease. In most instances the
temperature was still high and the illness in a more or less acute stage. But
in case VI the temperature was falling and came to normal eight days after-
wards; in case V the spleen was punctured on the first day of apyrexia; while in
case VII the temperature, which had only been raised for seven days, had been
subnormal for eight days before M. Melitensis was isolated from the spleen.

      In the third place, case VII is of great interest. It will be remembered that
this man was in hospital suffering from " remittent fever" from 5th September
to 2nd November 1904. It is probable, in view of the facts which we shall refer
to in a moment, that this illness was Mediterranean fever. For six months
after this illness he was free from fever and able to do his duty as a sepoy in the
regiment. After this interval he was again admitted into hospital suffering
from fever, which only lasted for seven days. There were at this time no other
symptoms. Now, the fact that M. Melitensis was isolated from the spleen eight
days after the temperature came to normal is positive proof that this fever of
short duration was an attack of Mediterranean fever. The question, then, is at
once raised, as to whether this last illness was a relapse after six months' interval
or a fresh infection. If it were a relapse, we have to assume that the causal
bacterium had remained alive in the spleen or other internal organ for six months
without giving rise to any symptom. If, on the other hand, it were a fresh
infection, we have to conclude that one attack of Mediterranean fever does not
confer immunity for any length of time. This latter conclusion is quite contrary
to all clinical experience. We are, therefore, inclined to support the other view,
namely, that we were here dealing with a relapse.

      In the fourth place, there is an interesting point in the epidemiology of this
disease which is raised by an analysis of our cases.

      Of the 17 cases which we have recorded above, 11 occurred in one regiment,
namely, the 27th Punjabis. We have seen that one of these cases was probably
a relapse, the original attack having occurred some months previously. The
remaining ten cases were admitted into hospital between the 4thMarch and
18th May 1905, but seven of these ten cases were admitted during the month