PKOCESS OF RIPENING IN THE TOMATO. 13 
phyll, which are masked in the red fruit) and (2) upon the presence 
or absence in the epidermal walls of a yellow pigment. In the pres- 
ence of the latter the red flesh is seen through a yellow screen, giving 
a more or less orange effect, but if it is absent the skin is transparent 
and the color a clear red. 
EXPERIMENTAL MATERIAL. 
The fruit for all the analytical work herein reported (with the 
exception of the "puffy" fruit discussed in the appendix) was obtained 
from plants of the Livingston Globe variety grown at Peters, Dade 
County, Fla. This variety is almost exclusively used for winter 
shipping to northern markets. For the life-history work the plants 
were grown in a field where the soil conditions represented the average 
of the entire acreage planted in tomatoes. These plants had the same 
treatment as the commercial plantings. They were set in the field 
in January and, following the local practice, were given four applica- 
tions of commercial fertilizer and the usual quantities of compost. 
In the former studies of the progressive changes in composition 
during ripening the tomatoes for sampling were classified by size 
and were usually picked at one time. This method of sampling was 
not deemed sufficiently accurate to be used in the present investiga- 
tion, for ripe tomatoes have a great range of variation in size, which 
fact alone should enable one to conclude that it is not the size that 
determines the degree of maturity. In order to establish a basis for 
selecting fruits of comparable maturity, blossoms were tagged and 
observations made as to the time of ripening. In a series of obser- 
vations made during the summer of 1918 at Arlington, Va., several 
hundred blossoms of Livingston Globe plants were tagged, and part 
of the fruit was picked every week, weighed, and measured. The 
important fact brought out by the experiment (Table III, Sec. A) is 
that the maturity of a tomato fruit depends upon age and not upon 
size. In the latitude of Washington, D. C. (at Arlington, Va.), 
49 days were required to bring the fruit to maturity, starting with 
the blossom. Of the 20 fruits left upon the vines, all colored at the 
same time regardless of size or weight. The experiment was repeated 
with plants grown in Florida, and the same results were obtained. 
(Table III, Sec. B). In this case 200 tomatoes remained on the 
vines at the end of 56 days, 181 of which were colored (turning to red) 
and 19 green. The variations in size and weight were as great as at 
Arlington, if not greater. It was impossible to judge to the day the 
age of the blossoms which were tagged, but the variation among 
blossoms was hardly more than one or two days. 
This method of obtaining tomatoes of known relative maturity is 
a fairly accurate procedure and is certainly to be preferred to that 
used by other investigators, who selected fruit according to size. 
