BRIEFER ARTICLES 
NEW NORMAL APPLIANCES FOR USE IN PLANT PHYSI- 
OLOGY. IV? 
(WITH TWO FIGURES) 
In the three preceeding articles I have described seven new pieces of 
normal apparatus devised for educational work in plant physiology; and 
below will be found accounts of two more, to be followed later by others. 
I call them normal appliances ayesaiie ae oA ssn and mene ss rape 
for their specific work, yield apy 
be used with economy of time and effort, sel are scbininabile at any time pa 
the stock of a supply company, which in the present instance is the Bausch 
and Lomb Optical Company of Rochester, N. Y. The development of 
this apparatus is part of the present movement toward the elevation of 
educational plant physiology to a higher plane of scientific logic, accuracy, , 
and efficiency 
VII. RESPIROMETER 
Respiration is a universal, and the most important, process of organic 
nature, and hence demands effective demonstration in all biological courses. 
Its study is the more valuable in plant physiology because, while respiration 
is essentially identical in plants and animals, it can be investigated far 
more readily in plants. Its central and crucial fact, energy-release, Can- 
not be directly demonstrated by any known method, but indirectly it can 
be proven and its amount determined through the identification and 
measurement of the gases absorbed and released in the process. For this 
purpose many arrangements have been described, of all grades from 
complex and precise to simple and inaccurate. The present new instru- 
ment is designed both to exhibit and to measure the gas exchanges in 
typical respiring material (e. g., germinating seeds), and to accomplish this 
with considerable accuracy and convenience of manipulation (fig. 1). 
The respirometer consists of three parts. First is the stoppered oval 
chamber for the seeds, with a water bulb at the bottom. Second is the 
measuring cylinder in open communication with the chamber, graduated 
from 75° to 100° of the combined capacity of itself and chamber, though 
the 75° mark is actually placed at 77° of the capacity. Third, and 
* Continued from Bor. GazetrEe 41:213. March 1906. 
Botanical Gazette, vol. 43] (274 
