20 
predecessor, and its period of rapid growth was abnormally short, so that 
in most cases only a single leaf was growing vigorously on each seedling. 
Working as I did in the open and therefore largely depending on nature 
for modifications of the environment, it was very difficult to secure any 
reliable data on the influence of the individual factors of the environment 
on so slow a process as growth. Of the plants represented in the fore- 
going table, those with even numbers were watered twice daily during the 
first two weeks. As compared with the alternate ones, which were placed 
in an otherwise drier place and which received as much as 1 millimeter 
of rain but once in fourteen days, the growth of the watered plants was 
much slower, but the relative rapidity of development was not affected by 
reversing the positions during the succeeding fortnight; from which it 
appears that the difference was inherent in the individuality of the plants, 
and that it is a matter of practical indifference to seedlings of the ages of 
the ones which I was observing whether they be given much water or very 
little. Observation of a seed bed where more than 5,000 nuts were placed 
to germinate justifies this conclusion. Differences in the exposure of 
different parts of this bed were not reflected in the growth of the seedlings. 
Until the area of the leaves permits an appreciable transpiration, the nut 
must contain all the water the seedling normally demands for its growth. 
If the husk is entirely dry the roots do not emerge from it, but this may 
as well be due to the extreme toughness of the dry husk as to the abnormal 
loss of water from the roots and to any inability on their part to absorb 
water. After this time a removal of the roots or a prevention of their 
growth by frequent moving stunts the development of the seedlings, and 
no amount of water will altogether obviate this result, though, of course, 
the injury is fatal only when excessive dryness or some other cause pre- 
vents the development of new roots. Whether the injury to the growth 
of the shoot of well-watered plants is correlative’ or because enough 
water can not be absorbed is uncertain, but in either case the leaving of 
the seedlings in the germinating bed after the nut’s supply of water ceases 
to satisfy all demands, will result in injury when they are transplanted, 
even under the most favorable conditions. 
The available moisture determines the rate of growth of the leaves of 
older plants to the practical exclusion of the influence of all other factors. 
My work on these older plants began after the influence of the dry season 
was seriously felt. Drought interferes first with the growth of the young- 
est individuals, the larger one suffering less, in proportion to the depth 
and extent of their root systems. The following table shows the growth 
of one plant (A) the development of which had practically been arrested, 
and of another (C) which up to the time of observation had compara- 
tively been but little affected. In each case a leaf tip barely protruded 
™Kny: Correlation in the Growth of Roots and Shoots. Ann. of Bot. (1894), 
8, 265. Townsend: The Correlation of Growth Under the Influence of Injuries, 
Ibid, (1897), 11, 509. 
