184 BLASTOGENIC VAEIATIONS. 



mals, and though, until the above-mentioned memoir 

 was published, there was practically no statistical evi- 

 dence as to the range of variation then experienced, as 

 compared with that found in sexually reproduced forms, 

 there was available the common knowledge of every 

 horticulturist and nurseryman, were he scientifically 

 trained or otherwise. Thus it had been thoroughly well 

 established that asexually produced forms, i. e., grafts, 

 cuttings, offsets, and tubers, are characterised by a very 

 much greater constancy than sexually produced forms, 

 e. g., seedlings. For concrete instances I cannot do bet- 

 ter than quote from those given by Mr. Sedgwick in his 

 recent Presidential Address before the British Asso- 

 ciation.* For example, in the asexual propagation of 

 the potato by tubers, the plants, be they, for instance, of 

 the Magnum Bonum variety, give rise to plants exactly 

 resembling their parent in foliage, flowers, and tubers; 

 if they be of the Snowdrop variety, the foliage, flowers, 

 habit, and tubers are also similar, and are totally dif- 

 ferent from those of the Magnum Bonum. " In this 

 way a favourable variety of potato can be reproduced 

 to almost any extent with all its peculiarities of earli- 

 ness or lateness, pastiness or mealiness, power of re- 

 sisting disease and so forth. By asexual reproduction 

 the exact facsimile of the parent may always be ob- 

 tained, provided the conditions remain the same." 

 Supposing, on the other hand, one tries to raise Magnum 

 Bonum plants from seed, in all probability not one of 

 the seedlings will exactly reproduce the parents; they 

 will all be different, both in properties of keeping, re- 

 sisting disease, and so forth. " Again, take the apple : 

 * Nature, vol. xl. p. 502, 1899. 



