April, 1915.] The Inheritance of Size in Tomatoes. 485 



The ideal plant fniit-stze would have been obtained if it had 

 been possible to harvest from each plant 1000 fruits or more and 

 the modal average taken. As this could not be done, it was 

 determined to select at least ten representative fruits from a plant, 

 the arithmetical average of which would be considered the average 

 fruit-size for that plant. In some cases, however, it was not 

 possible to harvest at least ten fruits so that a few plants are 

 represented by only four or five to nine recorded fruits. In the 

 selection of the fruits to be gathered the greatest degree of care 

 and accuracy was observed. One of the largest and one of the 

 smallest fruits were first taken, after which the remaining fruits 

 were selected as near to the mode of the fruit size as possible. It 

 is believed that the deviation of the recorded fruit-weight of any 

 plant, based on ten selected fruits, does not vary more than plus 

 or minus .2 gram from the actual fruit-weight which would have 

 been secured had all the normal fruits of that plant been harvested. 

 But even if the error of plant fmit-size were twice that amount it 

 would not materially affect the results of this work. 



RESULTS OBTAINED. 



The plants of the Yellow Pear tomato (carpellate parent) 

 possessed the following average fruit-weights: 



2-11-16. Plant 2 = 19.26 grams. 



" 3 = 17.84 



" 4 = 12.71 



5 = 17.84 



The average fruit-weight of this parent pure line is 10.91 grams. 



The variability of the average fruit-sizes of the plants of the 

 Red Currant tomato (staminate parent) is very slight and fruits 

 from only two plants were weighed. The following average fruit- 

 weights were obtained from these plants : 



7-11-2. Plant 1 = .66 gram. 

 " " 2 = .62 " 



The average fruit-weight of this parent pure line is .64 gram. 



The F-1 hybrid generation of this cross was found to be inter- 

 mediate in size. The plants possessed the following average 

 fruit- weights : 



17-12-2. Plant 1 = 1.90 grams. 



" 2 = 2.48 



" " 3 = 2.22 " 



" 4 = 3.46 



5 = 3.76 



The F-1 generation average is 2.76 grams. The geometrical 

 mean between the weights of the parents is 3.28 grams which is 

 only .52 gram more than the actual arithmetical mean of the 

 fruit-weights. It is to be also noted that two F-1 fruits are 



