124 
AMERICAN JOURNAL OF BOTANY 
[Vol. io, 
These experiments proving that water may be withdrawn from the fruits 
by the leaves are not given as proof of a new discovery. They are reported 
(a) because it appears that the importance of this phenomenon of water- 
withdrawal from the fruits by the leaves is not generally realized, ( h ) because 
of their bearing on the major experiments reported in this article, and (c) 
because of their bearing on our practice of growing citrus and similar plants 
under irrigation in a semi-arid region, rather than in their native habitats 
which have abundant rainfall and high humidity. Further discussions 
bearing directly or indirectly on this subject of withdrawal of water from 
the fruits by the leaves may be found in articles written by Renner (7), 
Livingston and Brown (5), Coit and Hodgson (3), Hodgson (4), and others. 
By referring to table 1 it will be seen further that there is very little 
difference between the water contents of the two ends of the lemon. This 
series shows an average of 0.35 percent more water in the stylar end than 
in the stem end. Some of the other series show even less difference than 
this series. 
It was found during these experiments that the water content of young 
fruits is affected by the availability of water. For example, in September, 
when the water supply was limited and relative evaporation was high, 
the water content of lemons 1.9 cm. in diameter averaged 54 percent. In 
December, when both rain and irrigation water were available and the 
amount of evaporation was comparatively small, the water content of 
lemons only 1.27 cm. in diameter averaged 68 percent. The variation of 
water content as affected by availability of water and climatic conditions 
was noticed also in the mature lemons. The variation may be as great as 
10 percent or more, but it is usually less. The range of differences of water 
contents in the mature fruits tested from the three experimental groves 
Was from 88.20 to 92.14 percent. Wehmer (8) reports only 82.64 percent 
for mature lemons. 
Further reference to table 1 will show that the increase in water content 
is comparatively small after the lemon has attained an average diameter 
of about 3.8 cm. 
During the course of these experiments it was noted that there were 
two periods in the year when there was a tendency toward cessation of 
growth. One occurred during the colder months and probably was due to 
climatic conditions that caused a decrease in metabolic activity and a 
tendency toward a normal rest period. The other occurred during the 
hottest months of the year and in all probability was due to low humidity 
and insufficient soil moisture. It is quite often the case in lemons that 
are approaching maturity that, when growth begins again after being 
checked, it occurs almost wholly in the peel, thus making a lemon with a 
thick peel which is undesirable for marketing. 
