252 
LOCK : THE GROWTH OF 
combination with the greater dryness of the air, must 
promote transpiration, and may thus influence the rate of 
growth of the younger members. 
2.— Comparison with Previous Observations . 
The results of the observations here recorded agree with 
those made by Kraus at Buitenzorg (1) in the average rate 
of growth recorded, and (2) in finding growth to be almost 
always more rapid during the night. Kraus also recorded a 
more rapid growth by day than by night on a single occa¬ 
sion. 
On the other hand Kraus states that the very marked 
oscillations from day to day which he observed showed no 
relation to external conditions. Since no record of these 
conditions is given, beyond the general statement of their 
marked uniformity, it is impossible to judge how far Kraus 
was correct in this conclusion. As far as I am aware, the 
only important differences between the conditions at 
Buitenzorg and those under which my observations were 
made consist in (1), the fact that the single clump observed 
by Kraus was younger than any of mine, and (2), that the 
climatic conditions were more uniform and probably on the 
'whole more favourable for rapid growth. Whether these 
differences are sufficient to account for the discrepancies in 
the two results appears to me to be somewhat questionable. 
Kraus suggested that the oscillations which he observed 
were discontinuous variations of growth (“ Stossweise 
Aenderungen ” of Sachs) of an extent hitherto quite unsus¬ 
pected. Reinke # showed however that what Sachs took to be 
spontaneous variations were probably to a large extent 
determined by small changes in the external conditions. He 
found that such “ Stossweise Aenderungen ” do take place in 
the plants which he examined, but that they required the 
most accurate methods of measurement applied at short 
intervals of time for their demonstration. It seems 
* Reinke. Untersuchungen über Wachsthum. Bot. Zeit. 1876. 
