NUTRIENT MEDIA AN'D METHODS OF CULTIVATION. 127 



sealing-wax, and the ring of putty is so plai-ed as to include one end 

 of it, leaving a small interval at the side, ov a. little notch is made 

 in the putty opposite, so as to afford an exit for the gas or vapour. 



Ku!. ."i7.— Moist Cell adaptko for Tu.vxsmissiox of Elkctwcity. 



Aj^plieatlon of J-nrciricif;/. — To study the effect of electricity 

 we may prepai-e a drop-culture iu the moist cell. The cover- 

 glass to bo used is provided with two strips of tinfoil, wliieh are 



Fill. 58. — APPAII.VTUS akkan\;ki> for Traxsmittixi; ELKcrmoiTY. 



isolated fi-om the brass of the micn^cope, and so arranged tliat a 

 current of electricity may be passed through them. 



A much simpler plan, which may also be employed, is to take 

 an ordinarv sxlass slide and coat the surface with gold-size. The 



