164 C. G. Williams and W. H. Waters. [May 12, 



ticular arrangement, a piston, working in a cylindrical prolongation 

 of this chamber, will rise or fall on each systole or diastole of the 

 ventricle. A lever being attached to this piston indicates the con- 

 dition of the ventricle upon a moving surface. 



From the construction it is evident that each systole of the ventricle 

 is indicated by a rise in the lever, making evident its character. 



After the character of the beats of a particular heart had been 

 observed while the normal blood was passing, the blood was then sent 

 through, containing from 0"1 per cent, to 0'4< per cent, of (3 lutidine, 

 and the character of the tracings studied. These were distinctly 

 modified ; the heart still beat, but never relaxed during diastole to its 

 full extent, in fact, showing a most decided increase in its tonicity. The 

 highest portions of the curve, indicating the condition of the ventricle 

 during systole, showed that that condition was much prolonged, that 

 portion of the curve being much rounder and longer. The normal 

 beat could be at once fully restored by repassing the saline blood 

 solution ; and a series of experiments, lasting some time, could thus 

 be taken. 



II is a specimen of these tracings, and should be read from right to 

 left. The beats on the extreme right are those of the ventricle before 

 the application of the alkaloid. When weaker solutions are used, 

 similar alterations occur, though naturally not so pronounced. 



In one experiment, where no beats occurred, the lever rose distinctly 

 on passage of the saline blood containing the ft lutidine, indicating 

 an increase in the tonicity of the ventricle. 



(7.) GashelVs Method. — In these experiments a method due to 

 Dr. Gaskell was used. A piece of fine silk was tied to the apex 

 of the ventricle, the heart cut out, and a slit made to open the ven- 

 tricular cavity. The heart was held just above the auricular ventri- 

 cular groove by a screw-clamp, and the free end of the piece of fine 

 silk attached to the ventricle tied to a lever, which had as its fulcrum 

 the rod of the stand holding the screw-clamp. This lever marked by 

 means of a fine piece of aluminium upon the smoked surface of a 

 revolving cylinder. 



Each contraction of the ventricle was thus indicated upon the 

 cylinder by a rise in the curve, any increase in the tone being 

 similarly indicated. 



The ventricle was first washed with normal solution to see its effect, 

 as it was in this that the ft lutidine was always dissolved, it being 

 necessary to determine that the effects produced were not due to the 

 solvent. This saline solution caused a slight fall of the lever, but 

 immediately that containing the ft lutidine (about 01 per cent.) was 

 applied, a small drop being sufficient, there followed a distinct increase 

 in the tonicity of the ventricle, the curve of beats being raised from 

 the abscissa line, as would naturally occur with this method of work- 



