No. 4.] CROSSING OF PLANTS. 43 



and, if in-breeding is attempted, it may be found that the 

 flowers will not in-breed. And the refusal to in-breed is all 

 the more strange because sexes are separated in different 

 flowers upon the same plant. In other words, in my expe- 

 rience, it is very difficult to get good seeds from squashes 

 which are fertilized by a flower upon the same vine. The 

 squashes may grow normally to full maturity, but be entirely 

 hollow, or contain only empty seeds. In some instances the 

 seeds may appear to be good, but may refuse to grow under 

 the best conditions. Finally, a small number of flowers may 

 give good seeds. I have many times observed this refusal 

 of squashes (Cucurbita Fepo) to in-breed. It was first 

 brought to my attention through efforts to fix certain types 

 into varieties. The figures of one season's tests will suffi- 

 ciently indicate the character of the problem. In 1890, one 

 hundred and eighty-five squash flowers were carefully pol- 

 linated from flowers upon the same vine. Only twenty-two 

 of these produced fruit, and of these only seven, or less 

 than one-third, bore good seeds, and in some of these the 

 seeds were few. Now, these twenty-two fruits represented 

 as many different varieties, so that the ability to set fruit 

 with pollen from the same vine is not a peculiarity of a par- 

 ticular variety. The records of the seeds of the seven fruits 

 in 1891 are as follows : — 



Fruit No. 1. — Four vines were obtained, with four dif- 

 ferent types, two of them being white, one yellow and one 

 black. 



Fruit No. 2. — Twenty-three vines. Fifteen types very 

 unlike, twelve being white and three yellow. 



Fruit No. 3. — Two vines. One type of fruit which was 

 almost like one of the original parents. 



Fruit No. 4. — Thirty-two vines. Six types, differing 

 chiefly in size and shape. 



Fruit No. 5. — Twenty vines. Nineteen types, of which 

 ten were white, eight orange, one striped, and all very 

 unlike. 



Fruit No. 6. — Thirteen vines. Eleven types, — eight 

 yellow, two black, one white. 



Fruit No. 7. — One vine. 



These offspring were just as variable as those from flowers 



