208 C. J. MARTIN. 
TV.—Errect or VENoM oN THE CrrcULATORY MECHANISM. 
The poisons of all snakes with which experiments have hitherto 
been made, depress the circulatory mechanism. Different venoms 
however exercise this action in different degrees, so that whereas 
interference with the circulatory apparatus plays a very important 
réle in the general phenomena of poisoning by some species of 
snake, with others such interference is, compared with its action 
in other directions relatively unimportant. 
In experiments with the frog’s excised heart, when the orgat 
is fed with a solution containing defibrinated blood, by means ofa 
Ludwig and Coat’s apparatus, the introduction of all kinds of 
venom into the feeding mixture, soon brings the contraction toa — 
standstill. If this has once happened, the further substitution of 
fresh defibrinated blood for the venom-containing solution does 
not effect a recovery. 
By direct observation of the heart in the opened thorax of 
mammals, in which artificial respiration was maintained, 
Feoktistow! observed great diminution in the cardiac contrac: 
tions, after the introduction of the venoms of Crotalus and 
Vipera berus. When these poisons were intravenously introduced, 
the contractions of the heart were at first diminished, and after: 
wards increased in number, becoming at the same time weaker 
and weaker until death occurred. S 
The best indication we possess of the efficiency of the circule 
tion is the arterial blood pressure curve. A variation in any 
the factors concerned in the general circulation will sooner 
later be manifested in this curve. It possesses the additions 
advantage that it lends itself in an admirable manner to the 
method of graphic record. A tracing of the pressure of ané 
may be allowed to run for hours, and at the end of the eee : 
are in possession of a record of every change of pressure which : 
occurred. Of course the chart has to be interpreted, and into that 
interpretation errors may creep, but by simultaneous © 
1 Loe. cit. 
