678 PROFESSOR H. N. MARTIN ON THE INFLUENCE OF VARIATIONS 
carotid instead of with the aorta; pulse-rate and mean pressure could then be 
recorded by manometers placed in the right subclavian and carotid arteries, and in 
correlation with the narrowed outflow orifice, the feeding tube, n, of the heart could 
be narrowed. Under such circumstances much less blood would be pumped around in 
a given time, and it would be possible to obtain the quantity requisite for carrying on 
an experiment from Dogs instead of from Calves. Pulmonary oedema and loss of 
cardiac elasticity would then occur much later. Of course in other cases, as when, 
for example, the greatest amount of blood which could be forced out from the left 
ventricle in a systole was to be sought, or the work done by the left ventricle under 
varying conditions, it would be necessary to use the wide tubes and stopcocks which 
I have above described, and these would almost necessarily lead to the use of other 
than Dogs’ blood for the nourishment of the isolated heart. 
Fourth, as a final remark before proceeding to give experiment protocols, I call 
attention to the fact that in the following tables it will be seen that now and then a 
slight rise of temperature occurs in the course of a cooling experiment, or a slight fall 
in the course of a heating. Such breaks were nearly always due to the necessity of 
changing the feeding Maeiotte’s flasks from time to time. While C is emptying and 
D filling, it is not possible to ensure that when D is in turn connected with the 
heart, the blood in it shall always be exactly of such temperature as to fit into the 
series of cooling or heating observations which had been carried on with C. An 
endeavour was always made to make the observations with the alternate flasks 
regularly consecutive as regards changes of temperature, and it will be seen that, in 
most cases, this was attained. When it was not, the resulting temporary rises or 
fails of temperature serve only to verify the general result; a slight and transitory 
heating in the course of a general cooling experiment quickens the pulse, and vice 
versa. 
I now give, in tabular form, the results of six experiments. 
Experiment I. 
April 24, 1882.—The Dog used weighed 5790 grins, and was chloroformed during 
the operation of isolating the heart. Venous pressure throughout equal to that 
exerted by a column of defibrinated Calf’s blood 15 centims. in height. Arterial 
pressure, measured in the right carotid, varied between 97 and 104 millims. oi 
mercury. All the systemic vessels but those of the coronary system of the heart were 
occluded at 12 h 50 m p.m. 
