April, 1915.] The Inheritance of Size in Tomatoes. 
489 
The average weight of fruit the F-3 parent, plant 10, is 2.22 
grams while the F-4 generation possessed an average fruit-weight 
of 2.215 grams—a remarkable similarity between weight of parent 
fruit and the average weight of fruit of offspring. It is further 
to be noted that six fruits are lighter and five fruits are heavier 
than 2.22 grams, so that there is as equal a variation as fruit-size 
as possible in the offspring on each side of this parental fruit- 
weight. This relation between parent and offspring is graphically 
shown on Plate XXII. 
Over 700 fruits were harvested from 74 plants in this series of 
experiments. This data is summed up and the relationship 
between the parental and hybrid fruit-weights is shown on 
Plate XXII. 
INTERPRETATION OF RESULTS. 
When the results, which were obtained, are interpreted it 
should be clearly kept in mind that the recorded weights represent 
the average fruit-weight of a single plant and not the weight of a 
single fruit. In practically all of the known experiments along 
this line the individual fruit-weights have been used as a basis for 
study and these weights have been shown in the tables of results. 
There is no evidence to show, in a number of experiments, at least, 
that any special care was observed in the selection of fruits, which 
seemed to be taken at random from a hybrid generation or a pure 
line of plants. The fluctuation in size of fruit on each plant; the 
difference in the number of fruits produced on each plant; and the 
variation in the length of the fruit-bearing period render the 
results secured by such harvesting liable to considerable error. 
On the other hand, when an accurate record is kept of each fruit 
and the average fruit-weight of each plant, more accurate results 
(especially the generation average based on the fruit-weight of 
the plants) are bound to be obtained. 
There are only a few recorded experiments which deal com¬ 
prehensively with the subject of the inheritance of size of fruit in 
the F-l generation. This scarcity of data, taken together with 
its complexity, render the correct analysis of this problem very 
difficult. Especially has there been a great deal of discussion 
among scientific men as to whether the F-l fruit-sizes approach 
more nearly to the geometrical or to the arithmetical mean between 
the parent sizes. 
Groth, basing his statement upon linear dimensions, reports 
that the size of the F-l tomato fruits is the geometric means 
between the parents. In this view he is supported by Bruce who 
had previously obtained like results with tomatoes. The data 
presented in this paper also shows that the F-l fruits of the 
tomato (currant-pear cross) are the geometric means between the 
parental sizes. 
