OTHER THEORIES OF SPECIES-FORMING. 



in it he makes a genuine contribution to scientific knowledge of 

 plant biology, albeit this knowledge is so far only proved to be 

 attainable and to exist. It is not yet exposed in its details and may 

 never be, however unselfish be the owner of it. For the going: 

 to oblivion of scientific data of an extent and value equivalent, I 

 may estimate roughly, to those now issuing from any half-dozen 

 experimental laboratories of variation and heredity, is the crying- 

 regret of all evolution students acquainted with the situation. The 

 recently assumed relations of Mr. Burbank to the Carnegie Insti- 

 tution are our present chief hope for at least a lessening of this, 

 loss. 



"But let us follow our saved plum seedling. Have we now to 

 wait the six or seven years before a plum tree comes into bearing 

 to know by actual seeing and testing what new sort of plum we 

 have? No; and here again is one of Burbank's contributions (not 

 wholly original to be sure, but original in the extent and perfection 

 of its development) to the scientific aspects of plant-breeding. This 

 saved seedling and other similar saved ones (for from the exami- 

 nation of 20,000 seedlings, say, Burbank will find a few tens or 

 even scores in which he has faith of reward) will be taken from 

 their plots and grafted on to the sturdy branches of some full-grown 

 vigorous plum tree, so that in the next season or second next our 

 seedling stem will bear its flowers and fruits. Here are years saved. 

 Twenty, forty, sixty, different seedlings grafted on to one strong 

 tree (in a particular instance Burbank had 600 plum grafts on a 

 single tree!); and each seedling-stem certain to bear its own kind 

 of leaf and flower and fruit. For we have long known that the 

 scion is not materially influenced by the stock nor the stock by 

 the scion ; that is not modified radically, although grafting sometimes 

 increases or otherwise modifies the vigour of growth and the extent 

 of the root system of the stock. 



"If now the fruit from our variant seedling is sufficiently desira- 

 ble ; if it produces earlier or later, sweeter or larger, firmer or more 

 abundant, plums, we have a new race of plums, a 'new creation' to 

 go into that thin catalogue of results. For by simply subdividing 

 the wood of the new branch, i. e., making new grafts from it, the 

 new plum can be perpetuated and increased at will. Simple, is it 

 not? No, it is anything but that in the reality of doing it; but in 

 the scientific aspects of it, easily understandable. 



"Perhaps it may not be amiss to call attention to what must be 

 the familar knowledge of most of us, and that is the fact that many 

 (probably most) cultivated plants must be reproduced by division, 

 that is by cuttings, buds, or grafts, and not by seeds, in order to 

 grow 'true.' For a piece of a cultivated plant will grow out to be 



