On the Physiology of the Embryonic Heart. 461 



January 26, 1893. 



Sir JOHN EVANS, K.C.B., D.C.L., LL.D., Vice- President and 

 Treasurer, in the Chair. 



A List of the Presents received was laid on the table, and thanks 

 ordered for them. 



The following Papers were read : 



I. " On the Physiology of the Embryonic Heart (Preliminary 

 Communication)." By J. W. PICKERING, B.Sc., Assistant 

 Demonstrator in Biology at St. Bartholomew's Medical 

 School. Communicated by Professor HALLIBURTON, F.R.S. 

 Received November 25, 1892. 



(From the Physiological Laboratory of King's College, London.) 



The object of the following experiments has been to study the effect 

 of varying conditions on the heart previous to the development of 

 a nervous mechanism, and thus to throw some light on the discussion 

 as to the relative importance of the two factors in the heart's action > 

 viz., the contractile tissue and the nervous elements. The heart I 

 have used is that of the chick* at a period of incubation of seventy-two 

 hours at a temperature of 38 C. In some cases the embryos have 

 been a few hours older or younger. The embryo is not removed from 

 the egg, but a window is cut 3 cm. square through the shell and 

 shell membrane, exposing the albumen and blastoderm, which remain 

 undisturbed ; the egg and embryo is fixed in a small chamber sur- 

 rounded on five sides by a water-jacket. The uppermost side is 

 covered with glass, while the air of the chamber is kept moist by the 

 evaporation of water from a small bowl placed inside it. The tem- 

 perature of this chamber can be kept constant or varied at pleasure.. 

 My experiments have fallen under three main heads : 1. The results 

 of varying the temperature. 2. The introduction of drugs. 3. Elec- 

 trical stimulation. In my full paper the results will be shown in 

 tables giving the number of heart beats per minute, the peculiarities 

 in the beat, when such exist, being duly noted. At present, however,, 

 I am only prepared to give an abstract of the results obtained, in so 

 far as temperature and drugs are concerned. The electrical experi- 

 ments are not yet completed. 



* Observations are being carried on upon the mammalian embryo in situ. 



