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



3. From an examination of all available data upon the 

 inheritance of fruit-size in the F-1 generation, it appears that, 

 when two varieties are crossed which differ widely in fruit-size 

 (the size of fruit of one parent being probably about two, three or 

 more times the size of fruit of the other parent), the F-1 fruit-size 

 will be nearer to the geometrical than the arithmetical mean; but, 

 when two parents similar in fruit-size are crossed, the size of fnu'ts 

 of the offspring will approach more nearly to the arithmetical 

 than to the geometrical mean. 



4. The average fruit-size of the F-2 generation does not 

 exceed and is even slightly less than the average fruit-size of the 

 F-1 generation. The segregation of size factors and the incomplete 

 dominance of the small size factors of the red cuiTant parent may 

 be explained by the assumption of at least four size factors. If 

 no parental sizes can be ever obtained, there may be more than 

 multiple factors involved. 



5. The fruits of the F-2 and F-3 generations agree fairly well 

 with respect to variability and average generation size. The F-4 

 fruits show diminished variability and size. 



6. This paper deals only with the inheritance of size in the 

 currant-pear tomato cross. Conclusions as to how far the results 

 obtained may be applied to the inheritance of size in crosses 

 between other species and varieties must be left to the accumula- 

 tion of further data. 



1. Belling, John. Velvet Beans crossed with Lyon Beans. Ann. Rpt. 

 Florida Agr. Exp. Sta. 1910: 79-92. 



2 Second Generation of the Cross between Velvet and 



Lyon Beans. Ann. Rpt. Florida Agr. Exp. vSta. 1911: 82-103. 

 3. Bruce, A. B. The Golden Mean. Science N. S. 40: 59. 



4 Heredite des caraters quantitatifs, (4 Conf .-int. Gene- 



tique Paris 1911 4pp.) 

 5. Castle, W. E. Heredity in Relation to Evolution and Animal Breed- 

 ing. 1911. 



6 Pure Lines and Selection. Jour. Hered. Vol. 5. 1914. 



7 The Inconstancy of Unit Characters. Amer. Nat. 



46: 352-302. 1912. 



8 Studies of Inheritance in Rabbits. Car. Inst. Wash. 



Pub. 114:5-70. 1909. 

 9. CoLLiN.s, G. N. The Value of First Generation Hybrids in Corn. Bu. 



P. Ind. 191. 1910. 

 10. Dk Vries, Hugo. Plant Breeding. 1907. 



11 The Principles of the Tlieory of Mutation. Science. 



N. S. 40: 74-S8. 1914. 

 12. East, E. M. The Genotype Hypothesis and Hybridization. Am. 

 Nat. 45: 160-174. 1911. 



13 Inheritance of Flower Size in Crosses between Species 



of Nicotiana. Bot. Gaz. 55. 1913. 

 14 A Mendelian Interpretation of Variation that is Ap- 

 parently Continuous. Am. Nat. 44: 65-82. 1910. 

 15. East, E. M. and Hayes, H. K. Inheritance in Maize. Con. Agr. 

 Exp. Sta. 167. 



