426 BIOLOGY: GENERAL AND MEDICAL 



from seeds and so would be lost were it not possible to 

 propagate them either by slipping or grafting. The graft- 

 ing of such plants also removes the risk of sporting and 

 reversion that would undoubtedly occur if seeds of the 

 fertile kinds were alone depended upon for their propa- 

 gation. Slow-growing fruit trees that might not bear 

 fruit for eight or ten years can be made to bear in one 

 or two years by grafting them upon already well-grown 

 trees of inferior quality. 



The stock that furnishes the roots is derived from one 

 plant, the scion that will bear the fruit is derived from 

 another and usually superior plant, Will the sap ascend- 

 ing from the inferior stock into the superior scion effect 

 any change in it, or will the returning sap from the scion 

 descending into the stock modify it? In the event of the 

 scion's being but one of many branches of the same plant, 

 will the products of the scion descending into the stock 

 and then returning to the other branches modify them? 



It seems difficult to get at the exact facts. As has 

 been said, the ancients believed in these modifications 

 and laid great stress upon them. Some modification 

 would be consistent with what has been found in certain 

 cases of grafting among animals, as when the graft of 

 negro skin becomes white by removal of its pigment, etc., 

 not with others, as the retention of their relative specific 

 characteristics by the anterior and posterior halves of a 

 frog developing from a tadpole composed of halves 

 derived from different individuals of different species. 



The subject has been carefully considered by Daniel, 

 who concludes that, "To say that no variation takes 

 place in the graft is the mistake of the moderns; to 

 believe that variation is constant, regular, and capable 

 of any modification is the error of the ancients. The 

 truth is to be found between these two equally exag- 

 gerated opinions." 



As the result of his survey of the subject and of his 

 own interesting experiments, Daniel came to the con- 



