The Ohio TSI^aturalist, 



and Journal of Science 



PUBLISHED BV 



The Biological Club of the Ohio State University. 

 Volume XV. APRIL, 1915. No. 6. 



TABLE OF CONTENTS. 



Perry — The Inheritance of Size iu Tomatoes 473 



Walton — A Land Planarian with an Abnormal Number of Eyes 498 



Bartlett— Key to the Seeds of the Wild and Cultivated Genera of Peas and Beans 



in Ohio 500 



THE INHERITANCE OF SIZE IN TOMATOES.* 



Fred E. Perry. 



INTRODUCTION AND STATEMENT OF PROBLEM. 



Only within the last decade has the attention of students of 

 heredity been turned toward the solution of the problem of the 

 inheritance of quantitative characters. From the very beginning 

 of the science of genetics qualitative characters have been studied 

 until, by means of a series of brilliant discoveries, our knowledge 

 of their inheritance has increased in a wonderful manner. Very 

 little progress has as yet been made, however, in the study of 

 quantitave characters and the inheritance of them has been 

 exceedingly difficult to analyze. 



Our present knowledge of heredity has been gained from a 

 microscopical study of the germ-cells, from a statistical examina- 

 tion of data bearing on heredity and from the experimental 

 breeding of plants and animals. The last of the above named 

 methods of studying heredity has been chosen for this work on the 

 inheritance of size in the tomato. 



Size is a general term which ineans the measurement or extent 

 of a thing as compared with something else or with a standard. 

 It is applied to all kinds of dimensions great or small. The 

 volume of a body is equal to the number of cubic centimeters 

 which it contains; it is the amount or measure of tridimensional 

 space. The mass of a body is defined as the quantity of matter 



*Contribution from the Botanical Laboratory of the Ohio State Uni- 

 versity, No. 87. 



473 



