188(5.] On the Action of the Excised Mammalian Heart. 461 



It was found by a practical optician to be impossible to wor!c 

 glasses on a cone of large diameter, consequently a conical tool was 

 constructed with an angle of 45° at the apex, and 8 inches diameter 

 at the base. 



A glass about 4 inches long was ground on the sides of this near 

 the base, and as the resulting lens if ground on plane glass would 

 have been too concave for most purposes, the outer side of the glass 

 was previously ground to a convex cylindrical curve, and its axis 

 applied parallel to the generating line of the cone in the plane of the 

 axis of the cone. 



The result was concavo-convex cylinders of varying power suitable 

 for the practical measurement of astigmatism. 



Lenses were exhibited varying from to — 6DCy, and from to 

 + 6DCy. 



III. " On the Action of the Excised Mammalian Heart." By 

 Augustus Waller, M. D., and E. Waymouth Reid, M.B. 

 Communicated by Prof. BuRDON Sanderson, F.R.S. 

 Received November 18, 1886. 



(Abstract.) 



The graphic method, the galvanometer, and the capillary electro- 

 meter were made use of in this research. The animals used were the 

 dog, rabbit, cat. rat, guinea-pig, and sheep. The chief results were as 

 follows : — 



1. Spontaneons ventricular contractions, complete and capable of 

 being recorded, continue after excision of the heart for periods which 

 are variable, but which as a rule are longer than has generally been 

 received to be the case (Czermak and Piotrowsky). 



2. Spontaneous ventricular contractions frequently outlast auricular 

 contractions, both spontaneous and excited. 



3. After spontaneous ventricular contractions have ceased to occur, 

 electrical and mechanical excitations can still provoke contraction. 



4. The length of contraction of both auricle and ventricle of the 

 excised heart is very great (15 to 20 times the normal duration), 

 whether the contraction be spontaneous or excited. 



5. The length of the latent period increases with the length of 

 contraction ; it may be as long as 0"75 sec. 



6. These phenomena (4 and 5) depend principally npon the sur- 

 rounding temperature. 



7. The heart (of a rabbit) can regain its excitability and its power 

 of spontaneous contraction after it has been frozen hard. 



