260 AGRICULTURE. 



of the small, juicy Love Apple. By cross- 

 fertilization " he succeeded in putting the solid 

 mass of this compound growth into the smooth 

 skin of the Love Apple, and then, by careful 

 selection and cultivation year after year, in- 

 creased its size and solidity until it became a 

 mass of flesh interspersed with small seed cells." 



Another good example is that of the varie- 

 gated hybrid carnation produced by crossing 

 the pink variety (Scott) with the white Mc- 

 Gowan (see colored plate). 



(ft) Limits of Crossing. The two plants to 

 be crossed must be members of the same family 

 and of species, or varieties which are in some 

 way closely allied. But even among these it is 

 impossible to determine, without actual experi- 

 ment, just what plants will cross with each other. 



This uncertainty of crossing among plants is 

 exemplified in the case of the pumpkin (Cucur- 

 bita pepd) and squash (Cucurbita maxima], 

 which are species of the same genus, yet will 

 not cross.* While with the strawberry and rasp- 

 berry, which belong to different genera, a cross 

 has been obtained. 



(<$) Varying Results of Crossing. Even when 

 a fertile cross is obtained, it may not show the 

 desired characters in the first generation. f It 



* Year-book, 1897, p. 389. 



f " The first generation is constituted by plants grown from the 

 seeds produced by the cross-pollinated flowers." Year-book, 1897, 

 p. 392. 



