1886.] Secretion in the Salivary Glands of the Dog and Cat. 203 



whether the action can be continuous or not turns on whether the 

 motion tends to preserve the foreign matter between the surfaces at 

 the points of pressure, as in the almost if not quite unique case of 

 the revolving journal, or tends to remove it, and sweep it on one 

 side, as is the action of all backward and forward rubbing with con- 

 tinuous pressure. 



The fact that a little grease will enable any surfaces to slide for a 

 time has tended doubtless to obscure the action of the revolving 

 journal to maintain the oil between the surfaces at the point of 

 pressure, and yet, although only now understood, it is this action that 

 has alone rendered machinery or even carriages possible. The only 

 other self-acting system of lubrication is that of reciprocating motion 

 with intermittent pressure and separation of the surfaces to draw the 

 oil back or to draw a fresh supply. This is important in certain 

 machinery, as in the steam-engine, and is as fundamental to animal 

 mechanism as is the continuous lubricating action of the journal to 

 mechanical contrivances. 



II. " The Electrical Phenomena accompanying the Process of 

 Secretion in the Salivary Glands of the Dog and Cat." 

 By W. Maddock Bayliss, B.Sc., and J. Rose Bradford, 

 B.Sc, Senior Demonstrator of Anatomy in University 

 College, London (from the Physiological Laboratory of 

 University College). Communicated by E. A. Schafer, 

 F.R.S. Received February 4, 1886. 



(Abstract.) 



The glands examined were the submaxillary and parotid of the 

 dog and cat, and in all of these we have determined that the process 

 of secretion is accompanied by definite electrical changes ; as, how- 

 ever, the submaxillary gland both in the dog and cat has been more 

 thoroughly examined than 4 the parotid, the present communication is 

 confined almost entirely to the former. 



The chorda tympani and sympathetic nerves were exposed in the 

 usual manner, divided, and the peripheral ends arranged for stimula- 

 tion, a canula being placed in Wharton's duct. The submaxillary 

 gland having been exposed was led off in the following manner. 

 One non-polarisable electrode was placed on the superficial or 

 cutaneous aspect of the gland, and the second electrode so arranged 

 in the wound as to touch the deep surface of the gland as close to the 

 hilus as possible without pressing on the duct. 



A Thomson galvanometer of high resistance was used. 



