Principles of Heredity 125 



basket grown from selected seed there were two plants of 

 different habit, seed-shape, etc. Each bore pods with seeds 

 few though large and round. Again Blue Peter (blue and 

 round) and Laxtori s Alpha (blue and wrinkled), grown in 

 my garden and left to nature uncovered, have each given 

 a considerable proportion of seeds with yellow cotyledons, 

 about 20 % in the case of Laxtons Alpha, The distribution 

 of these on the plants I cannot state. The plants bearing 

 them in each case sprang from green-cotyledoned seeds 

 taken from samples containing presumably unselected green 

 seeds only. A part of this exceptional result may be due 

 to crossing, but heterogeneity of conditions* especially in 

 or after ripening is a more likely cause, hypotheses I hope 

 to investigate next season. Hitherto I had supposed the 

 crossing, if any, to be done by Bruchus or Thrips, but 

 Tschermak also suspects Megachile, the leaf-cutter bee, 

 which abounds in my garden. 



Whatever the cause, these irregularities may undoubtedly 

 occur ; and if they be proved to be largely independent of 

 crossing and conditions, this will in nowise vitiate the truth 

 of the Mendelian principle. For in that case it may simply 

 be variability. Such true variation, or sporting, in the 

 pea is referred to by many observers. Upon this subject I 

 have received most valuable facts from Mr Arthur Sutton, 

 who has very kindly interested himself in these inquiries. 



* Cotyledon-colour is not nearly so sensitive to ordinary changes 

 in conditions as coat-colour, provided the coat be uninjured. But 

 even in monomorphic green varieties, a seed which for any cause has 

 burst on ripening, has the exposed parts of its cotyledons yellow. 

 The same may be the case in seeds of green varieties injured by 

 Bruchus or birds. These facts make one hesitate before denying the 

 effects of conditions on the cotyledon-colour even of uninjured 

 seeds, and the variation described above may have been simply 

 weathering. The seeds were gathered very late and many were 

 burst in Laxton's Alpha. 1 do not yet know they are alive. 



