By Sir George Steuart Mackenzie. 337 



impregnation, but unknown to us, that tend to variation. 

 This idea however must be limited ; because, when an expe- 

 riment of crossing is made, there may be many varieties of 

 Apples from which an accidental mixture may arise. Not 

 only may the pollen of several varieties be carried about by 

 insects and mixed together, and thus be applied to the female 

 organ selected for experiment, but it is possible that before 

 the particular pollen to be used is applied, impregnation, 

 partial or complete, may have taken place. To obtain, there- 

 fore, an absolute assurance of a simple mixture of two va- 

 rieties, only the two selected should be in the same garden. 

 I doubt if any mode of protection could be effected, because 

 the exclusion of the most minute insect is necessary ; and any 

 material used for protection so tight as to exclude these, 

 would exclude air also. It is more than probable we may 

 obtain abundance of new varieties by simply sowing the 

 pips of different Apples without artificial impregnation, 

 and by selecting such plants as bear certain marks that 

 give the fairest chance of good varieties, and which I will 

 point out. 



From the seeds of a single Apple, impregnated as above 

 stated, plants sprung, and five were selected, of strong growth, 

 and having the under side of the leaves more or less covered 

 with down. These are the most certain marks for selection, 

 but the down sometimes does not appear till the third year ; 

 the shape and size of the leaf are also good indications, 

 where the quantity of down might be considered rather 

 scanty. The quantity of this on the bark of the young tree 

 varies much, and I am inclined to reject all plants which have 

 but little on the shoots and leaves, but none that have much 



