April, 1915.] The Inheritance of Size in Tomatoes. 475 



number of locules. He has taken no weights and from weights 

 alone, it appears to the writer, can accurate data be secured to 

 show the inheritance of size. 



This problem in genetics was undertaken with tomatoes 

 because of their remarkable adaptability to work in heredity 

 and because no work had been previously done with them along 

 this line; and it was hoped that some contribution might be made 

 to our scanty store of knowledge regarding the inheritance of 

 quantitative characters — especially the inheritance of size. 



MATERIALS AND METHODS USED. 



Three crosses were made between pure lines of tomatoes in 

 the greenhouse of the Ohio State University. The first cross was 

 made (1911) between the little red currant tomato, Lycopersicon 

 pimpinellifolium, and the yellow pear tomato, Lycopersicon 

 lycopersicon (Lycopersicon esculentum). In this cross L. pim- 

 pinellifolium was used as the staminate parent and L. lycopersicon 

 as the carpellate parent. The reverse cross-pollination was m.ade 

 many times but fertilization never occurred. The second cross 

 was made (1912) between Livingston's Beauty (carpellate parent) 

 and the Yellow Pear (staminate parent). The third cross was 

 made (1914) Avith Livingston's Beauty as the carpellate parent 

 and Bonnie Best as the staminate parent. It is to be noted that 

 the first cross was made between species while the second and 

 third crosses were made between varieties of L. lycopersicon. 

 All of these pure lines with their hybrids have been growing in the 

 greenhouse and results have been obtained, but completed data 

 is now at hand from only the first cross and this paper will deal 

 almost entirely with results obtained from this hybridization. 



These cross-pollinations were made with the utmost care and 

 every precaution was taken to provent the presence of any unde- 

 sired pollen grains. Two unopened flowers of the same age were 

 selected — each one on a plant of the pure line to be crossed. A 

 capsule of paraffined paper was placed over the staminate bud 

 and both ends were tightly filled with cotton so that the entrance 

 or escape of pollen was absolutely prevented. A tag was attached 

 to the stem of the flower to serve as a means of identification. The 

 sepals, petals and stamens of the carpellate bud were carefully 

 cut away with sterilized pollinating instruments; the stigma was 

 examined with a hand lens to be sure that no pollen grains were 

 present, and the gynecium was capsuled and tagged. After three 

 or four days both capsules were removed and pollen from the sta- 

 mens of the staminate flower was transferred upon a steriHzed 

 glass slide to the stigma of the carpellate flower. Then the 

 pollinated gyneciuin was capsuled again and left for about a week 

 until fertilization had taken place and the young fruit had begun 

 to enlarge. All the pollinating instruments were carefully ster- 

 ilized over an alcohol flaine, both before and after they were used. 



