31 



IV. " On the Electrical Condition of the Egg of the Common 

 Fowl." By JOHN DAVY, M.D., F.R.S.S. L. & E. &c. 

 Received May 19th, 1859. 



(Abstract.) 



The structure of the egg suggested to the author the idea of its 

 exerting electrical action. This was confirmed on trial. Using a 

 delicate galvanometer and a suitable apparatus, on plunging one wire 

 into the white, and the other, insulated, except at the point of con- 

 tact, into the yolk, the needle was deflected to the extent of 5 ; and 

 on changing the wires, the course of the needle was reversed. "When 

 the white and yolk were taken out of the shell, the yolk immersed 

 in the white, the effects on trial were similar ; but not so when the 

 two were well-mixed ; then no distinct effect was perceptible. 



Indications also of chemical action were obtained on substituting for 

 the galvanometer a mixture consisting of water, a little gelatinous 

 starch, and a small quantity of iodide of potassium, especially when 

 rendered very sensitive of change by the addition of a few drops of 

 muriatic acid. In the instance of newly-laid eggs, the iodine libe- 

 rated appeared at the pole connected with the white ; on the con- 

 trary, in that of eggs which had been kept some time, it appeared at 

 the pole connected with the yolk, answering in both to the copper 

 in a single voltaic combination formed of copper and zinc. 



The author, after describing the results obtained, declines specu- 

 lating on them at present, merely remarking, that in the economy of 

 the egg, and the changes to which it is subject, it can hardly be 

 doubted that electro-chemical action must perform an important 

 part, and that in the instance of the ovum generally, i. e. when com- 

 posed of a white and of a yolk, or of substances in contact, of hete- 

 rogeneous natures. 



