224 



POPULAR SCIENCE MONTHLY. 



Thallus and Fruit of Spineless Cactus. 



burr is originally intended to keep off the birds. In developing a 

 superior variety of the Persian (often called English) walnut (Juglans 

 regia), the shell was made too thin, so that the birds could break in. 

 It was necessary to make new selections and crossings to thicken the 

 shell and still retain its other superior qualities. 



The Pierce grape was a bud 

 sport from the Isabella,, producing 

 much larger fruit. This bud 

 sport remains constant. All the 

 seedlings even from it are similar 

 to the Pierce grape, following the 

 bud sport {Pierce) and not re- 

 verting to the real parent form of 

 the Isabella. Some ripen early, 

 some late ; some are pale, and 



some are black; but all resemble the Pierce more than the Isabella. 



Cultivating a choke cherry, the seeds all from one parent tree, many 



variations are found, although the soil in which they are placed is 



uniform. Among them was 



found one variant less bitter than 



usual ; others earlier or later 



ripening and with larger or 



smaller fruit or leaves, and an 



almost bewildering number and 



variety of other variations. A 



peach-almond cross often develops 



a tree as large as ten peach trees 



or almond trees of the same age. 



Sometimes a similar cross with 



different individuals of the same 



species will produce opposite or 



totally different results, owing to past heredity, either recent or far 



back. Crosses are sometimes more vigorous than either parent and 



more than any descendant, but other cases are just the reverse. The 



more variant crosses are often less vigorous, and sometimes yield 



seedlings that can not exist. Sometimes all die in the fruiting season. 



A peach named ' Quality ' is one of the best peaches extant — a cross 



•of the Muir and the Crawford. A cross of the nectrine and peach 



also produces variant types of value. In some hybrids of petunia 



and tobacco, the roots fail while the tops may be of unusual vigor. 



These individuals can only be kept alive for any length of time by 



grafting, another instance — if other were needed — of the parallelism 



of crossing and grafting. 



'' A character may be latent through many generations or centuries, 



The Plumcot— an Absolutely New Fruit. 



