474 The Ohio Naturalist. [Vol. XV, No. 6, 



which it contains. This definition of mass assumes that the 

 quantity of matter is detennined 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 inany 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 linc;;r 

 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 cS 

 specific gravity would be reduced to a minimum within a certain 

 definite variety. Since linear dimensions cannot give a tn^e 

 conception of the size of fruit and since there is but little variatu.n 

 pnjbable 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 arc 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; tho\- 

 grow without difficulty and mature nonnal fruit readily under 

 greenhouse conditions. 



In spite of the remarkable adai)tation 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 

 ])lant 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 



