294 BOTANICAL GAZETTE [NOVEMBER 
be tested were transferred from a pure culture to the hanging- . 
drop by means of a sterile platinum needle, the utmost care 
being taken to prevent the adherence of the spores in bunchesin 
making the inoculation. The cover bearing the culture was 
then inverted on the cell and gently pressed until completely 
closed, except for the minute opening already fully described. 
When a set of cultures was complete all were placed ina ther — 
mostat which was kept at a constant temperature of 28°C 
Care of cells, covers, pipettes, etc-—After completion of a 
series of cultures, all bottles, rods, etc., were thoroughly washed x 
and placed in running water for several hours, then dried and 
placed in a dry oven at 160°C. When the cultures in the cells 4 
matured, the covers were removed and the cells were thor 4 
oughly washed under the water tap, wiped, air-dried, and finally 4 
placed in the dry oven at 110°-120°C. for an hour. - 
insured thorough sterilization, and at the same time drove off the 
last trace of any volatile substance that might have escaped the 
washing. The covers were first boiled in strong KOH, then in 
several changes of water; this was followed by boiling in suas 
H,SO,+K,Cr,O,. They were again thoroughly rinsed : 
again boiled in four changes of clear water, rinsed in 95 set 
alcohol, wiped, and sterilized at 160°C. The pipettes : 
cleaned by forcing water through them for an hou 
to the water tap. They were then sterilized in a steat be 
An occasional culture was found to be contaminat 
bacteria, due no doubt to dust particles bearing spe 
in contact with the cultures in the making. Such co 
however, by bacteria or fungi amounted to less bp I ie 
f preliminary r 
Vapor pressures in the cell. 
cal chemists that every liquid has a certain vapor i. 3 vapor 
water at standard atmospheric pressure and 28 C. stance 
pressure of 28™" of mercury. Any addition fee 
substances to this water will lower its vapor Pree T se vapor 
substance added be hygroscopic the lowering Te 
