1912 - 13 .] Studies on Periodicity in Plant Growth. 
89 
Research Apparatus and Methods. 
The necessary statistics for construction of the growth curves were 
obtained : — 
(a) From direct readings taken twice or oftener during the twenty- 
four hours. 
(b) From continuously recorded curves on the automatic recorder. 
Fig. 1 . — Sketch of Automatic Apparatus for measuring the growth of Aerial Roots — 
Monstera deliciosa. 
a = glass tube in which root tip is growing ; w=weight counterpoising the glass tube. 
For (a) the apparatus used was of the simplest character possible : — 
1. For root growth the root was grown in water in a glass tube 
graduated in millimetres, and the increments read off by eye. 
2. For the growth of suhaerial organs the organ was arranged vertically 
or horizontally, with the least possible disturbance along a bar with milli- 
metre graduations and increments read off as necessary. 
3. A simple type of arc auxanometer was made use of (Trans. Scot. Mic. 
Soc., 1908, vol. v. p. 66). 
In (b) precision auxanometers were used giving continuous revolutions, 
one per day, or one per week, or intermittent (one movement per hour), as 
was found necessary in the particular case. The organ was connected by 
thread to one end of a light lever, the other end of which, carefully counter- 
