306 BOTANICAL GAZETTE [APRIL 
factor, the ability to absorb and translocate very probably becomes 
so. This would then be a typical “saturation deficit.” If this 
be true, then the maximum to be very high will evidently occur 
after a very rapid rise, while a less rapid but prevailingly high 
transpiration rate will utilize the reserve water and reach the limit 
entailed by anatomical features without having so high an index. 
There is evidence for support of this in the two curves in question; 
the average of the indices for the first six hourly readings for July 21 
being 0.396, while the average for July 16, computed from the 
same leaves, for the first six hours preceding the maximum is 
0.391, which means that the water loss from a unit area from the 
first rise in the morning until the attainment of the maximum was 
practically the same. Granting that the translocating ability 
limits the maximum rate of transpiration, then, since we are con- 
sidering data calculated from the same individual with an interval 
of but five days, we would expect the water loss up to the time of 
incipient drying to be approximately the same, when the time peri- 
ods are the same. We may further assume that the water reserve 
will be quite constant for the same individual on consecutive days 
when the growth water is adequate to meet all the needs of the 
plant, for this will be dependent upon the structural features of 
the plant, which remain quite constant. A slight variation in the 
reserve would follow a variation in food storage, which is a fluc- 
tuating factor, and slight differences in the total transpiration up 
to the time of the deficit depression will result from different absorp- 
tion rates which fluctuate with soil temperature. If the tran- 
spiration index is high in the morning, the maximum transpiring 
power will of necessity appear early, for the reserve is utilized 
rapidly. If the rate is low in the morning, the maximum, if it is 
attained, will occur relatively late. The maximum transpiring 
ability is limited by the rapidity of rise in the index and the trans- 
location-absorption ability. The maximum translocation doubtless 
occurs when the protoplasmic condensation within the mesophyll 
of the leaf is greatest, since at that time the osmotic pressure within 
the cells is highest, and the cells will exhibit their greatest affinity 
for water. This occurs two or three hours after the maximum 
transpiration. The relatively high transpiration index preceding 
