E. N. Salaman 19 



bred it, this type of " round " potato assuming large proportions ; fevv 

 examples with a diameter over 2 inches occur, although oval and 

 kidney from the same original parent stocks may be of large size and 

 weight. 



A typical specimen of this " round " type is represented by the first 

 tuber of (?", Plate VI. The tuber is apple-shaped, its upper or proximal 

 end as well as its distal or crown end is depressed, and the height is 

 less than either its width or its depth. The actual dimensions are : — 



Length Breadth Depth Batio 



1, 5/16 2, 2/16 1, 1/16 =21 : 34 : 17 



One of the tubers of the parent A has the following measurements: — 



Length Breadth Depth Ratio 



1, 5/16 2, 2/16 1, 1/16 =21 : 34 : 17 



The most characteristic feature is the stumpiness of the tuber in 

 relation to its breadth. 



Potatoes are raised commercially by the vegetative method, thus a 

 crop of " Magnum Bonums " raised to-day should be regarded as merely 

 an offshoot^a cutting so to speak — of a seedling raised some time 

 before the year 1876. In other words the tens of thousands of tons 

 which in the past 34 years have been grown of this stock are for 

 scientific purposes merely replicas of a particular tuber of a particular 

 individual, and hence the continuity through the intervening years of 

 the variety's characters. Tubers that are grown by this vegetative 

 means, within limits, reproduce themselves in their original shape more 

 or less exactly, though I think, and hope to prove, that the degree to 

 which a potato reproduces its shape vegetatively depends in large 

 measure on its gametic constitution. 



It may therefore be confidently expected that whilst a crop raised 

 from a typical " round " such as A by vegetative means will remain 

 perfectly true to type (and this indeed has been proved in the case of 

 A itself, by growing it in 1908 and 1909), a crop raised say from the 

 fifth tuber of No. 67, Plate V, might produce tubers more or less 

 uniform and unlike the type A. A family raised by seed from any 

 of the individuals, however aberrant in shape, will probably produce 

 a set of seedlings at least as uniform as the family A itself 



The variation of this " round " type, if grown vegetatively, so far as 

 my experience goes, is very slight or indeed none at all. The variations 

 of the type as raised sexually by seed are slight but definite, being 



3—2 



