220 
(VII) the principle of coil-contacts has been put into practise; the 
self of the current blowing away the opening-spark. 
The space-marking on the paper is arranged, by using the fact 
that the ink (a solution of eosin in water and some glycerin) remains 
wet for some time. On a metal strip (60) stiff bristles have been 
glued, at distances of 5 mM., which drag over the wet ink and 
make checks in the lines. 
_ An electro-time-sign (58) draws a straight line parallel to the 
abscissa of the record and makes checks e.g. every 10 minutes. 
As the lines are drawn 1,5 mM. apart, the distance in mM. between 
two time-checks (devided by 1,5) gives the increase in 10 minutes. 
As it may happen that a check falls just before the carriage will 
be driven back, and the next check just after this moment, the 
maximum error that may occur will be 20u. In this way a simple 
method has been found, to compare the results with those of other 
investigators. 
Lastly a second time-sign (58) can be put into action from the 
experiment-room. One can, by pressing a bell-push, put a point on 
the paper at the moment, when light is dosed or when the auxano- 
meter has been put on the clinostat, etc. 
Next figure 6, a little reduced in size, gives the record of 1 mM. 
Fig. 6. Record of 1 mM. growth. Each-line at R gives the time needed for 
10 « growth; 7'= time-line ; 
every 10 minutes the increase is constantly 290 «. 
growth, belonging to a paper of 4,05 M. in length, containing the 
record of 27 mM. growth, in the dark. | 
Utrecht, November 1921. Botanical Laboratory. 
