R. N. Salaman and J. W. Lesley 35 



was no significant difference eitlior in tlie number of seeds per berry or 

 in the germination of the seed or in the mortahty among seedhngs. 

 Neither flower nor tuber colour showed any significant difference. 



Two types of inflorescence occurred in these famihes. In the " simple '' 

 type (see plate) the primary axis divides into several (usually two) 

 secondary axes, each of which forms a scorpioid cyme. In the " compound "' 

 type (see plate), however, the two or more secondary axes divide again, 

 forming tertiary axes and some of these divide so that axes of the fourth 

 or fifth order are formed each of the ultimate branches forming a 

 scorpioid cyme as before. Similar types of inflorescence have been 

 studied by Crane (8) in tomatoes. The proportions of these two types 

 in the present case showed no significant difference in the reciprocal 

 crosses. 



The proportion of plants which flowered in Edgecote Purple >: Edzell 

 Blue, however, was nearly double that in the reciprocal family. (In 

 1920, 23 per cent, as against 13 per cent. ; in 1921, 72 per cent, as against 

 37 per cent.) Both families were equally vigorous. In the late summer 

 when many of the plants had ceased to flower several seedlings in Edge- 

 cote Purple :■' Edzell Blue were seen to bear berries, often a dozen or 

 more on a plant. In the reciprocal cross, on the contrary, extremely 

 few plants had berries and these in but small numbers^. It occurred to 

 us that this difference might be due to a difference in pollens, as seed 

 and berry production in potatoes is frequently determined by pollen 

 (of. Stuart(3)). As a first step, all the available pollens were examined. 

 In Edgecote Purple x Edzell Blue all the 18 plants tested had "abundant" 

 pollen. This was in accord with the frequent presence of self-set berries 

 in this family. In the reciprocal cross 1.5 plants were recorded where 

 pollen was described as follows: 



Abundant ... 1 Small ... ... 8 



Medium ... 1 Very few grains 5 



Only one plant was "abundant" as against the entire 18 in the 

 reciprocal family. A remarkable difference in the male organs of the 

 reciprocal cross thus came to fight, a difference which is paralleled by 

 previously observed difference in fruit and seed jiroduction. Both 

 famihes were grown on by tubers in 1921 and a further sowing made of 

 1919 seed of the cross Edzell Blue x Edgecote Purple. 



' The berries both from Edgecote Purple •: Edzell Blue and Edzell Blue y Edgecote 

 Purple contained seed. The average germination capacity was 90 % and the lowest 38 %. 

 We are indebted to Mr Saunders of the National Institute of Agricultural Botany for 

 testing the seeds. 



3—2 



