Sinnott and Durham: Summer Squash 



185 



have frequently arisen from doubles 

 and doubles from singles. 



A number of crosses involving dilifer- 

 ences in blossom end are reported 

 in Table VI. 



Although a study of the pure lines 

 shows that this character is doubtless 

 inherited, there is evidently a good deal 

 of difference in the manner of its in- 

 heritance. We may say in general 

 that the single type tends to be domi- 

 nant over the double and to be more 

 abundant in the F2. 



HABIT OF VINE 



No well marked running vines were 

 developed in the pure lines studied, 

 but in a number of lines a distinct 

 tendency to run was observable and 

 gave a very different habit to the plant 

 from the normal "bush" type. In 

 crosses of the bush form with the 

 runner, the Fi showed a rather inter- 

 mediate condition and in the F2 there 

 was a marked preponderance of bush 

 plants. In many cases, however, the 

 line between the two types was very 

 hard to draw. 



OTHER CHARACTERS 



A number of other characters are 

 distinctive of particular lines and are 

 therefore clearly inherited, but their 

 expression is difficult to record and no 

 definite data as to their manner of 

 inheritance has been gathered. 



Such a character is that of highly 

 developed teeth in the "starfish" type 

 shown in (Fig. 18). The number of 

 teeth and the development of the 

 shelf or border around the fruit 

 are also distinctive (compare plant at 

 left with two plants in middle of lowest 

 tier in Fig. 18). 



The deeply furrowed surface seen 

 in 85BS3 (Fig. 18), is a very constant 

 feature of this line. 



The "dome" shape of the fruit 

 is perfectly constant and even tends 

 to segregate out somewhat in crossing. 



The size of the seed cavity may be 

 relatively large, as in most plants, or 

 relatively small. These differences are 

 clearly characteristic of their respective 

 lines. 



The size, shape, and color of the seed 

 are clearly inherited. 



The size of the blossom end scar 

 varies greatly, regardless of whether it 

 is single or double. It may be little 

 more than a small button or it may be 

 large and conspicuous. In some cases, 

 notably the "85" series (Fig. 18), it is 

 very deep, running well down into 

 the fruit. Usually, however, it is 

 rather shallow. 



Leaf characters also distinguish par- 

 ticular lines. The leaves may be three, 

 five, or seven lobed, or may be almost 

 unlobed. They may be erect and 

 closely arranged on the stem, giving the 

 plant a very bushy appearance; or they 

 may be spread out more loosely. 



Finally, there are differences in 

 amount and character of fruit yield, 

 some plants being heavy yielders and 

 others relatively light ones. Certain 

 types produce only one or two large 

 fruits and others a considerable number 

 of smaller ones. 



It should be noted that in all the 

 characters which have been studied in 

 crosses, it makes no difference whether 

 the character is brought in through 

 the male or the female parent, recipro- 

 cal crosses being essentially similar. 

 This result is directly at variance with 

 those reported by Drude and Lotsy. 



