474 
The Ohio Naturalist. 
[Vol. XV, No. 6, 
which it contains. This definition of mass assumes that the 
quantity of matter is determined by the effect of force upon it. 
The weight of a body is the force with which the earth attracts 
that body. It is the measure of the mutual attraction between 
that body and the earth. The weights of bodies are proportional 
to their masses at any given place on the surface of the earth. 
The tomato fruits are of a very irregular shape as they vary in 
every degree from a flattened spherical to a nearly perfect spher¬ 
ical, egg, plum or pear-shape. Not only do the various species 
and varieties differ widely from each other with respect to shape, 
but there is also considerable variation within the limits of each 
variety, which fact is especially noticeable when the large, culti¬ 
vated tomatoes are considered. The large, flattened spherical 
or cup-shaped tomatoes, like Ponderosa or Livingston’s Beauty, 
are very irregular in shape with many depressions and rounded 
projections. The long, pear-shaped tomatoes vary especially 
with respect to length, thickness and breadth of neck. Some 
fruits have distinct depressions at both stem and distal end while 
othe fruits have protuberances at these places. A tomato with 
these protuberances may have the same linear dimensions as a 
tomato with depressions but yet be of a very different size; or a 
pear-shaped fruit may have identical linear dimensions with an 
egg or plum-shaped fruit and yet there be a great size difference. 
It can thus be readily seen that it is impossible to get a good con¬ 
ception or estimate of the size of a tomato fruit from its linear 
dimensions. 
It is not probable that the specific gravity of the cellular tissue 
of the fruits varies to any great extent. At least the variation of 
specific gravity would be reduced to a minimum within a certain 
definite variety. Since linear dimensions cannot give a true 
conception of the size of fruit and since there is but little variation 
probable in the specific gravity of the fruits, it is evident that the 
weight of a tomato fruit is the best possible index of its size. 
Tomatoes are well adapted to the study of inheritance. The 
cross-breeding of the different varieties and species is compara¬ 
tively easy and the plants may be readily propogated in a vegeta¬ 
tive way. The tomato contains many heritable units, the inher¬ 
itance of which may be studied. The plants-' are hardy; they 
grow without difficulty and mature normal fruit readily under 
greenhouse conditions. 
In spite of the remarkable adaptation of the tomato to work in 
inheritance of size or weight, no such accurate work has been 
done with this fruit. A number of men have performed experi¬ 
ments upon the inheritance of the qualitative characters of the 
plant and fruit. Groth seems to be the only one who has worked 
with the inheritance of quantitative characters of fruit and he 
has been studying such characters as the linear dimensions and 
