-i8 3 - 



mix with the running squashes of the Hubbard, Marblehead, 

 Boston Marrow, turban and mammoth types. 



3. Impotcncy of individual pollinations. — In pumpkins and 

 squashes the flowers are either wholly stamiuate or wholly pistil- 

 late, and they cannot, therefore, pollinate themselves. But the 

 two kinds of flowers are borne upon the same plant. Pollination 

 between two flowers upon the same plant I have termed individual 



■ 



pollination, in distinction from close pollination, or pollination of 

 the flower by itself, and from cross pollination, or pollination be- 

 tween flowers on different plants. It has been shown by Darwin 

 and others that pollen is sometimes impotent upon the pistil of 

 the same flower, and I have been much interested, therefore, in 

 the relation of pollen to pistils upon the same plant in monoecious 

 species (those in which the sexes are borne in different flowers 

 upon the same plant). My attention was first called to this sub- 

 ject in 1889, when some twenty or thirty squash flowers were pol- 

 linated from flowers on the same plant. A number of fruits grew 

 to maturity, but they invariably produced poor seeds. This year 

 the subject was carefully examined. 185 squash and gourd flow- 

 ers of some fifty varieties were individually pollinated. 163 of 

 these did not produce fruit. The remaining 22 carried fruits to 

 maturity, but in every case the seeds were thin and worthless. 

 These 22 fruits represented 13 bush summer squashes of various 

 kinds, 5 small ornamental gourds, and four crosses between 

 bush squashes and gourds. In cross pollinations made during the 

 same time and in the same manner, a large part of the crosses 

 were successful, indicating that the failure of the individual 

 crosses was due to the inability of the pollen to fertilize the 

 ovules rather to incidental methods of operation. The experi- 

 ment indicates that pollen of squashes which cannot produce fer- 

 tile seeds may still cause the development of the fruit. This in- 

 fluence of pollen is well attested in other instances, but it is not 

 impossible that squashes may sometimes develop without any 

 pollination whatever. At any rate we have found this to be the 

 case in some other cucurbits, and it is a point upon which we are 

 still working, and concerning which we have much data. 



This impotcncy of individual pollen is a matter of immense im- 

 portance to originators of varieties. It is commonly held that the 

 best way in which to " fix " or render permanent new varieties, 

 so that they will reproduce themselves by seedage, is to iu-breed 



