NUTRIENT MEDIA AND METHODS OF CULTIVATION. 



127 



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

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

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



FIG. 57. MOIST CELL ADAPTED FOR TRANSMISSION OF ELECTRICITY. 



Application of Electricity. To study the effect of electricity 

 we may prepare a drop-culture in the moist cell. The cover- 

 glass to be used is provided with two strips of tinfoil, which are 



Fii.. 58. APPARATUS ARRANGED FOR TRANSMITTING ELECTRICITY. 



isolated from the brass of the microscope, and so arranged that a 

 current of electricity may be passed through them. 



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

 an ordinary irlax slide an. I coat the surface with gold-size. The 



