1016 
Immediately on the completion of intervals of time which were 
as far as possible equal, the length of the zones was measured 
„accurately to '/, m.m. L calculated from the increase in length 
the average rate of growth per m.m. during each separate space of time. 
In making the measurements a great difficulty was the determination 
of the exact boundary of the zones, because the portion of the stem 
on which the mark had been placed, grew at the same time. I there- 
fore tried to determine as far as possible the middle of the mark. 
In my later observations, I succeeded in avoiding the error due to 
this, by marking alternate zones with a lengthwise line. I then took 
the extremities of the longitudinal mark as the zone-boundary. 
Rapid growth also caused this boundary to become indefinite and 
difficult to determine. 
To gain an idea of the errors in my observation, I frequently also 
measured in the course of my observations the zones which had 
already been found to have grown out. 
I thus obtained numerical data concerning the length of the same 
zone measured at different points of time. 
The greater number of these data were identical, only a few 
deviated. Calculation showed that the average error was smaller 
than the expected degree of accuracy. 
In Asparagus officinalis LiNN., Ginkgo biloba Lann., Hedera colchica 
Hoen and Linum usitatissomum Lixn., the whole region of growth 
formed a single curve of rate of growth, i.e. regularly increasing 
growth from below upwards and then decreasing growth above this. 
Acer dasycarpun Euru., Acer platanoides Linn, Deutzia scabra 
TasG., Lonicera tatarica Laxn., Syringa vulgaris Linn, and Viburnum 
Veitcht C..H. Wricut showed a similar 
curve of rate of growth with this dif- 
| 
ference that the zones in which the 
nodes were situated showed less 
growth than the zones lying nearest 
to them. 
Fig. 1 shows the curve of rate of 
Fig. 1. Deutzia Scabra Tune. growth in Deutzia Scabra Thbg. from 
13—17 Juli. 13% 16-17% July”). 
') On the abscissae axis the zones have been plotted at equal distances. The 
thin lines give the division-marks between the zones, the thick lines are the nodes. 
As ordinates | have plotted the average rates of’ growth of each zone during 
a definite space of time. 
The rate of growth of the lowest zone of the stem is given in the curve on 
the left, and that of the uppermost zone on the right. 
ed 
