PRODUCTION OF NEW VARIETIES. 21 



land produced the seed of all his new and excellent varieties 

 of the cherry. 



The interesting fact that fruit trees which grow alone and 

 distant from any other sorts are more apt to reproduce these 

 sorts from seed with but little variation, than seeds from the 

 same sorts in mixed orchards, shows to what extent the spon- 

 taneous crossing or mixture of varieties may be constantly 

 going on in such orchards. 



When a cross is obtained between two different species, in- 

 stead of between mere varieties, it is termed a hybrid. But 

 while varieties of the same species intermingle freely, the 

 operation rarely succeeds between fruits of different species. 

 The gooseberry, currant, and black currant, species of the 

 same genus, and nearly related, have never produced a useful 

 hybrid. Neither has any ever been obtained between the ap- 

 ple and the pear, or the pear and the quince. But different 

 species of other plants, as the Heaths, and some of the Cacti, 

 intermingle freely. Hybrids are frequently sterile ; or if they 

 possess the power of reproduction by seed, the progeny often 

 returns to the state of one or the other of its parents. 



Amongst common fruits, there are some undoubted hybrids. 

 Such are the Kieffer and LeConte types of pears, which are 

 hybrids between the common pear ( Pyrus communis) and the 

 oriental pear (Pyrus Sinensis). 



There are many hybrid grapes, and some of them, as Aga- 

 wam, Salem, and others, are of commercial importance. There 

 is a large class of hybrid raspberries (Rubus occidentalis x R. 

 strigosus), represented by the Shaffer and other Purple Canes. 

 The Wilson Early blackberry is a hybrid of the blackberry 

 (Rubus nigrobaccus} and the dewberry (R. villosus}. In gen- 

 eral, however, less is to be expected from hybrids than from 

 the selected progeny of crosses between varieties. As a mat- 

 ter of fact, most varieties of fruits are chance seedlings, no 

 one knowing their exact parentage. Amongst fruits, purpose- 

 ful plant-breeding has yet played a very small role. (See Bai- 

 ley, " Plant-Breeding.") 



