1876.] 



On the Mycelium of Smallpox of Sheep, 



259 



so that the tension of the electricity as compared with a chloride-of- 

 silver cell is as 



The copper disk, after its separation from the zinc, acts as a condenser 

 to the latter ; and as soon as the copper disk is connected automatically 

 with earth the bound electricity of the zinc is set free, and the needle of 

 the electrometer makes a sudden jump. To observe this effect it is 

 necessary to work the apparatus slowly. 



When earth-connexion was made with the copper disk, and also sub- 

 sequently with the zinc disk after the charge had been given off from it, 

 and before a new contact, no sensible difference was observed in the 

 deflection of the electrometer. 



With an ordinary Elliott tangent-galvanometer, and indeed with one 

 twice as sensitive as those generally made, not the slightest deflection of 

 the needle was manifested ; with, however, a Thomson galvanometer a 

 deviation of the needle was obtained of 35 divisions in one direction and 

 35 divisions in the other, according as the zinc conductor was connected 

 with one or other end of the galvanometer and the other end wdth earth. 



The current, though feeble, is quite manifest nevertheless. To form 

 a rough notion of the electromotive force, a piece of copper wire 0*5 inch 

 long and 0-03 inch diameter was connected with one end of the galvano- 

 meter, and a piece of zinc 0*25 inch diameter and 0*5 inch long with the 

 other, and the one held between the right-hand finger and thumb, and 

 the other between the left-hand finger and thumb, using g-L shunt in the 

 galvanometer or only part of the current ; this produced a deviation 

 in the scale of 50 divisions with dry fingers, and 150 divisions when the 

 fingers and thumbs were moistened ; so that the quantity of electricity 

 developed by the contact of dissimilar metals is consequently extremely 

 small when the area (28'27 inches) of each disk is taken into account. 



XXVII. ^^Note on the Mycelium described in my Paper on 

 Smallpox of Sheep.'' By Dr. E. Klein, E.R.S. Received 

 June 7, 1876. 



In the above paper, which was printed in the Philosophical Transactions 

 (vol. 165. pt. 1), I described and figured, in Section iv. part c, the pre- 

 sence, in the lymphatics of the skin of the pock, of what I regarded 

 to be the mycelium of a fungus which I termed Oidium variolce (see 

 figs. 9, 10, and 11 of that paper). Similar features were described and 

 figured in the cavities of the primary and secondary pustules. 



My attention has been drawn by Dr. Charles Creighton to appearances, 

 in many respects similar to those described by myself, which he found in 



146-7 X 20 



95 



-= 30-88 to 1. 



