R. N. Salaman 



27 



same individual, is met with in the case of the heterozygous 

 variety. 



The examples of heterozygous potatoes which have been tested, 

 viz. " Flourball " D\ H\ H'", K'^, K^ and D, varying as they do from 

 kidney to pebble, testify to this. 



The degree of variation in the shape of tubers of some given sort 

 is iu itself very variable, but I think it would be acknowledged that 

 the kidney types vary most. A striking example of this is shown on 

 Plate XXVIII. reproduced b}' permission of Messrs Sutton, where a 

 kidney potato, " Superlative," is photographed in the clamp, and whilst 

 the majority of the tubers are kidneys, a large percentage are best 

 described as pebbles. 



The variety H^, Plate X, so clearly demonstrated to be hetero- 

 zygous, is a remarkably uniform kidney shape, but out of less than 

 half-a-bushel it is possible to pick out potatoes varying from a very 

 long to an obtuse ellipse, Fig. 2. 



Fig. 2. These drawings are tracings of sagittal sections of potatoes of tlie individual H'. 

 The long and transverse axes are shown. The depth is less than the transverse 

 diameter. 



The Depth of the Eye. 



The potato tuber has scattered on its surface buds from which grow 

 the shoots ; the buds are known as " eyes." 



The potato eye consists essentially of two parts, a central spot or 

 shoot, and an overhanging ridge or brow which is curved, and whose 

 concavity always points downwards or distally. 



The eye is recognized to occur in two forms and is known as either 



