1905-6.] Standardising Suprarenal Preparations. 159 
dilatation of the pupil resulted, but it was followed on long 
exposure by a marked contraction. Probably any slight injury to 
the eye during enucleation may interfere with the result. 
3. On Arterial Blood Pressure. — Ehrmann, who published his 
results when my investigations were nearly completed, also tested 
the minimal effect on the blood pressure in cats. He quotes one 
experiment in which 0*08 mg. (0‘02 mg. in 1 c.cm. of which 4 c.cm. 
were injected) gave a slight increase of blood pressure. The effect 
was just appreciable when five-eighths of that quantity was used. 
In these experiments the ansesthetic was ether, and the injections 
were made into the jugular vein. 
Elliott,* in investigating the disappearance of adrenalin from 
the body, estimated its strength by means of the blood pressure in 
cats under urethane and with cut vagi. The maximal pressure 
curves given with increasing doses of adrenalin injected in equal 
times were found. The intervening values were estimated from 
these curves. The rise varied wfith the vein into which the 
injection was made, being greatest in the external jugular. The 
blood pressure results were corroborated by the typical eye 
reactions — widening of the eyelids, dilatation of the pupil, and 
retraction of the nictitating membrane. 
Before the publication of Ehrmann’s and Lawen’s papers, I had 
investigated the availability of the perfusion method and of the 
method of determining the effect on arterial pressure. 
In the perfusion experiments, a cannula was tied into the aorta 
of a pithed frog, and the fluid to be tested was allowed to flow by 
gravitation from a reservoir. After passing through the vessels of 
the frog, the fluid escaped through the cut sinus venosus. As the 
difference in viscosity of the perfused fluids was practically 
negligible, the effect of each could be determined by the rate of 
flow from the cut sinus. To avoid the laborious proceeding of 
counting the drops, a graphic record was taken. The perfused 
fluid, as it escaped, was allowed to drop on a light aluminium plate, 
| inch square, which was fixed obliquely to the free end of a lever. 
The movement of the lever caused by the fall of a drop of fluid 
was transmitted by means of tambours to a second lever, to the 
* Journal of Physiology, vol. xxxii. p. 447. 
