176 C. J. MARTIN. 
(4) Influence of previous injection of the venom into an animal, — 
on the result of a subsequent injection. 
If a small dose of venom (less than 0:0001 gramme per kilo.) be 
introduced into a dog, the blood, as previously mentioned, exhibits a 
for about two or three minutes after the completion of the injee — 
tion, an increased coagulability. That is to say, samples drawn 
i! 
| 
during this period clot sooner than control samples taken previous 4 
to the injection. At the same time the arterial blood pressute 
falls to one half or one third of its former height. After twenty 4 
or thirty minutes the pressure begins slowly to rise, and thirly ‘ 
minutes to one hour from the time of the injection may have ; 
reached or even exceeded its original height. During the whole 
of this period, with the exception of the first two or three minutes 
samples of blood taken from an artery show very marked retarda- 
tion in coagulation. 
If now, one hour or more after the first injection, a second 
injection containing a much larger quantity (ten or twenty times 
the first dose) be made, the introduction of this second dosé 
increases the coagulability of the blood during the subsequent! ht 
minutes, but samples of blood drawn five or ten nine after the a 
second injection clot however only after the lapse of | bout 
and in many cases spontaneous coagulation is altogether in abey- 
ance. I have always introduced, at the second injection, a quantity 
of the venom which would inevitably produce complete arterial 
and venous thrombosis in an animal which had not beet pre 
viously subjected to an injection of a dose sufficient to establish # 
negative variation. 
On other occasions I have given a dog yet a third injec 
containing comparatively speaking, a very large dose, viz.i— 
gramme per kilo. This amount, dissolved in 3 c.c. of 77, ™ 
solution was injected, as rapidly as possible, into the femoral 
jugular vein. This third injection failed to produce any i ae 
coagulability of the blood, and the samples drawn immediately 
after the injection did not clot at all. 
