156 The Botanical Gazette. [May, 
serve as paddlés; the spaces serve to admit the water upon 
the tube. 
The sheet is now bent around a cylinder of a somewhat less 
diameter than the test tubes to be used. This gives the jacket 
a tension which enables it to grasp the tube firmly. By 
erecting the paddles in a direction corresponding to the cut 
of the chisel, the inner surface of the jacket is left smooth and 
does not scratch the glass in slipping it on or off. 
For the support of the tube while under the shower bath I 
used two ceiling hooks which I screwed into a narrow board 
long enough to rest across the sink. They should be so lev- 
elled that the end of the tube containing the cotton plug will 
be very slightly elevated. The rapid motion will prevent the 
agar from gravitating down the tube while water will not run 
on to the plug 
slide the frame backward so that the water strikes the aoe 
dles when the tube immediately revolves as shown 10 neh 
3, plate XI. The supports must not pinch the tube in Mie 
least else the friction will interfere with the freedom of wld 
revolutions. The jacket and frame when not in use shot 
be kept dry to prevent rust. the 
_ A little practice will determine the proper distance et 
Jacket from the end of the tube. It is best to have it 4 of 
ferent diameters can be rolled with the same jacket 51 to the 
— permits some variation in its accommodation 
ube. : 
Alabama Polytechnic Institute, Auburn. 
