[Vor. 5 
262 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
It must, of course, be here emphasized that such data can- 
not in themselves be considered as quantitative. The diffi- 
culties and errors involved in the methods and procedure of 
enzyme extraetion under the most favorable conditions pre- 
clude the consideration of resulting data as other than com- 
parative. With this limitation, however, they should, whether 
of positive or negative nature, nevertheless prove of interest. 
Метнорв AND MATERIALS 
For the control of temperature conditions a large constant 
temperature water bath of 85 liters capacity was devised. De- 
tails of construction of the apparatus will be reserved for 
future publication. It will suffice to say that the water con- 
tainer was a rectangular galvanized iron tank 112 cm. long, 
36 em. wide, and 41 cm. deep, insulated with solidly packed 
excelsior. The reservoir permitted the use of two parallel 
rows of six two-quart glass Mason jars which served as con- 
tainers of the material studied. Heat maintenance and con- 
trol were electrical. Uniformity of temperature in the bath 
was insured by two electrically driven paddles of the pro- 
peller type. An indicator arm with pen attached, similar to 
the recorder of a Friez thermograph, was connected with the 
heat-controlling device and registered temperature deviations 
on the dial of a clockwork recorder. With preliminary trial 
and adjustment it was found possible to maintain a desired 
temperature within 1-1? C. 
The plant material studied was in all cases brushed and 
washed in tap water, disinfected by immersion for two or 
more hours in a 0.1 per cent solution of mercuric bichloride, 
washed for several hours in running water, and finally dipped 
in two changes of distilled water and one of 70 per cent alcohol, 
when it was turned out on clean absorbent paper and when 
dry placed in the jars. Each lot was weighed and trans- 
ferred to a numbered cheese-cloth bag before disinfection, 
thus reducing handling to a minimum. 
At the beginning of an experiment the control portions and 
those to be etherized were placed in the water bath at the 
