36 Genetic Studies in Potatoes 



such as foliage, tuber shape, stem colour and stolon length and, in 

 respect to certain families, of flower colour also. No doubt this is merely 

 due to their homozygous constitution resulting from self-fertilization 

 and isolation. 



The " prostrate " plant covers a large area of ground with its dense 

 foliage and it has been found that the soil so covered is always damp, 

 so that even in the drought of 1911 these plants were always moist at 

 the roots and maintained a high cropping rate. It has occurred to us 

 that such a habit might prove of value in sub-tropical countries and 

 arrangements for experimenting with the variety in Palestine had been 

 made in 1913 with the late Dr A. Aaronsohn of the Haifa Technical 

 Institute. The materials sent, however, were all destroyed by the Turks, 

 together with the Institute, during the war. The tragic death of 

 Dr Aaronsohn, to whose memory we would like to pay homage, is not 

 merely a personal loss but one that is irreparable in the sphere of 

 agricultural research in the East. 



The foregoing results may now^ be briefly summarized. Two varieties 

 differing in habit of growth have arisen from the normal potato plant. 

 An inherited variation has been brought to light which affects the 

 anatomical structure and rigidity of the stem and consequently the 

 habit of growth. 



The " prostrate " variety breeds true. The genetic relations as far as 

 they have been elucidated show that the " prostrate " differs from the 

 " upright " in at least two and probably in three factors, and finally that 

 the "prostrate" habit is not correlated with other characters. 



In conclusion the authors wish to acknowledge the valuable assistance 

 given by Miss E. Hagger in continuing at Barley the experiments during 

 the war and making many valuable observations. They also desire to 

 tender their thanks to Mr Bateson and Professor Biffen for permitting 

 some of the cultures to be grown in their experimental grounds and for 

 the unfailing encouragement they have afforded them. 



