A New Auxanometer . 1 
BY 
F. M. HAINES, 
Demonstrator , Botanical Department , East London College, 
With two Figures in the Text. 
H AVING regard to the slow rate of growth usually obtained under 
laboratory conditions, and the small magnifications effected by 
existing auxanometers, an endeavour has been made to design an instru- 
ment which will record the growth of the plant on a much larger scale, that 
is with a much higher ‘ magnification 5 than has, as far as the author is 
aware, ever been attempted hitherto, and which will at the same time allow 
of the observation extending, if necessary, over a period of at least three or 
four days. Although the form of apparatus to be described can claim no 
advantage over its predecessors in the matter of simplicity, the manipulation 
should present no difficulty after the first setting up, and the care necessary 
will not seem disproportionate when the fact is taken into consideration 
that the instrument is capable of magnifying the growth to such an extent 
that its representative length on the recording graph may be varied at will 
from 20 to ioo times the actual increase in length of the plant. 
An experimental instrument fitted with everything except the com- 
pensating gear for the stretching of the fibres has shown itself capable of 
giving smooth curves on the recording sheet for periods of two days with 
a magnification of fifty, and has been checked by a Ganong auxanometer 
working on the same plant ; but as, owing to the present conditions, only 
a rough working model has so far been constructed, the present account 
must be looked upon as merely preliminary. 
The chief features in the new instrument are as follows : 
i. The magnification is not produced by concentric pulleys of different 
radii arranged as in Ganong’s instrument, nor by a lever as in Farmer's, but 
by employing a differential pulley, the plant being (indirectly) connected by 
1 From the Botanical Department, East London College. 
[Annals of Botany, Vol. XXXIII. No. CXXX. April, 1919.] 
