1876.] On certain cases of Electromotive Force. 183 



unboiled tube being the most turbid of the three. The infusion here 

 was peculiarly limpid after digestion ; for turnip it was quite excep- 

 tional, and no amount of searching with the microscope could reveal in 

 it at first the trace of a living Bacterium ; still germs were there which, 

 suitably nourished, passed in a single day into Bacterial swarms without 

 number. Five days have not sufficed to produce an effect approximately 

 equal to this in the boiled tube, which was uninfected but exposed to the 

 common laboratory air. 



There cannot, moreover, be a doubt that the germs in the air differ 

 widely among themselves as regards preparedness for development. Some 

 are fresh, others old; some are dry, others moist. Infected by such germs 

 the same infusion would require different lengths of time to develop 

 Bacterial life. This remark applies to and probably explains the different 

 degrees of rapidity with which epidemic disease acts upon different people. 

 In some the hatching-period, if it may be called such, is long, in some 

 short, the differences depending upon the different degrees of prepared- 

 ness of the contagium. 



The author refers with particular satisfaction to the untiring patience, 

 the admirable experimental skill, the veracity in thought, word, and deed 

 displayed throughout this first section of a large and complicated inquiry 

 by his assistant, Mr. John Cottrell, who was zealously aided by his 

 junior colleague, Mr. Frank Valter. 



February 4, 1876.— J". T. 



January 20, 1876. 



Dr. J. DALTON HOOKER, C.B., President, in the Chair. 



The Bight Hon. Lord Aberdare and the Bight. Hon. George Sclater- 

 Booth, whose Certificates had been suspended, as prescribed by the 

 Statutes, were balloted for and elected Bellows of the Society. 



The Presents received were laid on the table, and thanks ordered for 

 them. 



The following Bapers were read : — 



I. u Certain cases of Electromotive Force sustained by the Action of 

 Electrolytes on Electrolytes." By J. Hopkinson. Communi- 

 cated by Sir W. Thomson. Beceived November 29th, 1875. 



In the following experiments the electromotive force was observed by 

 a quadrant electrometer arranged for maximum sensibility; the con- 



