35 



in a definite region, the branches of which are at once distributed as scions. 

 It is now thought that all individuals produced by asexual propagation act- 

 ually represent only the continuation of the tree first developed from the 

 seed. Now, since each individual has its own life period, this many-headed 

 individual which we call a "variety" must fall victim to death after a definite 

 length of time. In this way is explained the universally simultaneous sick- 

 ening and dying out of many a variety. As examples of this kind are given 

 Golden Pippin and Borsdorfer, two varieties of apple, on the degeneration 

 of which there developed an extensive literature in the seventies of 

 the last century^. 



Other old fruit varieties (especially apple) are said to sufifer simultane- 

 ously from sterility wherever grown, become cankered and die. Potato var- 

 ieties, formerly widely acknowledged to be excellent, are no longer true to 

 type and disappear from the market. The orange trees found formerly in 

 European gardens as most vigorous old specimens become diseased every- 

 where in spite of the greatest care. The celebrated orangeries at Sanssouci. 

 Dresden, Cassel, Versailles etc. have vanished or are represented only by a 

 few often sickly trees. Indeed, even in Italy, large plantations of lemon and 

 orange trees have been attacked by diseases at present apparently incurable. 

 The cause is said to be a weakness of growth w^hich makes itself gradually 

 increasingly felt, together with a diseased condition of the root. The same 

 may be affirmed of grape vines and of olive trees, pomegranates, the Ericas 

 (heathers) of Cape Colony, the Australian Papilionaceae and Myrtaceae. 

 which formerly, as "Javanese" plants in special conservatories, formed the 

 decoration and pride of gardeners. Even in our species of grains, we have 

 noticed the disappearance of the good old varieties. This is the opinion of 

 the representatives of the theory of degeneration. 



The theory of the continuity of an individual through a.\\4he scions, for 

 Avhich the stock, or the parent plant rather, serves only as nurse, is based on 

 the presupposition that this individual retains all its characteristics un- 

 changed during its whole existence as a variety wherever grown and on the 

 different stocks. For, at the moment when it must be granted that the habi- 

 tat or stock may change any peculiarities, a variation in the length of life 

 due to different nutrition must also be considered a possibility. For this 

 reason those who defend the theory of degeneration and a fixed life period 

 of varieties (especially Jensen among botanists) insist upon the fixity of 

 characters and support their theory by the fact that the varietal character 

 always remains constant in seeds and in cuttings as well as in grafts. Defi- 

 nite shoot variations produced on any one specimen (variegated leaves, split 

 leaves, forms with weeping branches, fasciations etc.) which can always be 

 transmitted by grafting on new stock are proofs most often stated. 



1 "Wearing out of varieties," Gardeners Chronicle 1875. "Do the varie- 

 ties wear out?" ibid. "Degeneration from senility" in the Fruit Manual 1875. 

 "Golden Pippin degenerated" in Gardeners' Chronicle 1875. Compare "Bericht uber 

 die Verhandl. d. Sektion fur "Weinbau in Trier," 1875, etc., etc. 



