122 BOTANICAL GAZETTE [SEPTEMBER 
power lamps was introduced at the wall socket. The current source 
in all cases, however, was thesame. The sliding contact rheostat R 
has a resistance of 1770 ohms and a capacity of 0.45 amperes; while 
Rt has a resistance of 464 ohms and a capacity of 1.2 amperes. The 
voltmeter V was attached to the binding posts C, C'. The milli- 
volt meter A (text fig. 2) was of Weston Electrical Instrument 
Company manufacture, with an upper range of 150 milliamperes 
and a lower range of 1.5 milliamperes. M represents the moist 
chamber. 
The seedlings were sacetally lifted from the sawdust, the adher- 
ing particles brushed off with a small camel’s hair brush, the length 
measured with a small millimeter rule, and then by means of 
tweezers they were placed on the small glass fork which served as a 
Fic, 2.—Apparatus and measuring instruments 
support and which was attached to the upper electrode by means 
ofarubber band. The cotyledons of the seedling were now brought 
in good contact with the moist kaolin of the upper electrode, and 
the lower electrode (shaped like the letter J) moved upward so that 
the kaolin came in contact with not more than the first millimeter 
of root tip. The door was now placed in position and the current 
turned on with the key of the socket at B, B'. The time of exposure — 
was measured with a stop watch. During exposure voltage and 
amperage were read on the instruments. 
For the cytological phase of the investigation the moots, imme- 
diately after exposure, were killed in Flemming’s fluid. It should 
be stated that control seedlings were suspended in the moist cham- 
ber, in every case, near those being exposed to the current, and the 
roots killed and sectioned as the treated roots for comparison. 
