April, 1915.] The Inheritance of Size in Tomatoes. 479 



The experiments of Phillips in 1912 (40) upon the inheritance 

 of size in ducks were more extensive than the work of Castle or 

 Ghigi. He crossed a Mallard with a Rouen duck and found that 

 the F-1 birds were intennediate in size as compared with the 

 parents. Segregation was present in the F-2 generation. Phil- 

 lips concludes, "The amplitude of variation of the F-2 fowls is 

 greater than that of the F-1 fowls but does not extend beyond the 

 nearer limit of the respective grandparental races." 



Nilsson-Ehle (1908) showed how the Mendelian notation for 

 the inheritance of qualitative characters might be used as a basis 

 for the explanation of the inheritance of quantitative characters. 



East in 1910 (14) in ignorance of Nilsson-Ehle's 1908 paper, 

 developed a similar theory and showed how certain data on the 

 inheritance of the number of rows of grains on an ear of maize 

 could thus be analyzed. 



Emerson in 1910 (19) issued a paper on the inheritance of 

 quantitative characters in Cucurbita pepo, Phaseolus vulgaris and 

 Zea mays. He showed segregation of size factors but offered no 

 Mendelian explanation. 



Johannsen (32) crossed two lines of beans and worked with the 

 inheritance of length and breadth. He found the F-1 generation 

 intennediate between the parent biotypes. The F-1 beans were 

 no more variable than the parents but no definite conclusions can 

 be drawn from this fact as only a limited number were grown. 

 The F-2 and F-3 generations showed greatly increased variability 

 over that of the parent biotypes. The length of the parent beans 

 differed widely from each other. Neither the F-1 nor F-2 genera- 

 tion reached the extremes in length of the parent biotypes but the 

 F-3 generation did reach those extremes. The breadth of the 

 parent beans were very similar. The F-2 generation exceeded in 

 breadth the extremes of the parent biotypes, while the F-3 genera- 

 tion more widely overlapped those extremes. 



Belling in 1912 (1 and 2) crossed two widely different bean 

 varieties. The F-1 generation exceeded in size of seed and plant 

 either of the parents. The F-2 generation showed marked 

 variability. 



East in 1913 (13) worked upon the corolla length of Nicotiana 

 and found the F-1 hybrid corolla length to be the geometrical 

 mean between the parent lengths. The F-2 generation showed 

 greater variability than the F-1 generation. 



Groth in 1912-13 (26, 27, 28 and 29) conducted extensive 

 experiments upon the inheritance of tomato seedlings, leaves and 

 fruits. He worked with linear dimensions and found the F-1 

 fruit to be the geometrical mean between the parental dimensions. 

 Marked segregation of size occurred in the F-2 generation. His 

 Mendelian explanation of the results is very complicated and will 

 be discussed later in this paper. 



