2M Rediqdication in Gametic Series 



During the years 1906 and 1907 we were engaged upon an investi- 

 gation of the inheritance of the hooded character in the sweet pea, of 

 which an account appeared in Report IV to the Evohitiou Committee 

 of the Rojal Society, 1908, pp. 7 — 15. Among several thousand plants 

 bred and recorded in this set of experiments there occurred a single 

 individual (in Exp. 35, R.E.C. IV, p. 15) exhibiting striking peculiarities 

 in the form of its flowers. These were .small and much deformed 

 (cf. PI. XL, fig. 1). The standard failed to become elevated, the keel 

 was cleft distally so that the anthers were partially protruded, while the 

 stigma projected far beyond the petals, and was carried on in the line 

 of the carpels instead of being abruptly bent at right angles to them as 

 in the normal flower. At the time of its discovery, in reference to the 

 open " mouth," and the protruding " tongue " represented by the pro- 

 jecting style, the plant was dubbed " the cretin," by which term we shall 

 subsequently refer to this peculiar malformation. The fact that the 

 style protrudes is due to the malformation of the keel which is unable 

 to curve the growing style and cause it to assume its natural position. 

 Fuller experience of these cretins has shewn us that the petals may 

 sometimes be nearly as large as in normal flowers (cf PI. XL, fig. 2), 

 and that the standard may sometimes become elevated in the normal 

 way (cf PI. XL, fig. 3). The size of the flowers may vary considerably 

 on the same plant, and hitherto where the larger form of flower has 

 occurred the plant has also borne others more nearly resembling the 

 original type. The degree to which the keel is cleft also shews some 

 variation, but in all cases these cretins have the peculiar and character- 

 istic straight stigma. 



Our original cretin was found in 1907 and was used as the pollen 

 parent to fertilise various sterile' sweet peas. Tiie F^ plants, which 

 flowered in 1908, were all indistinguishable from normal sweet peas. 

 The normal form of flower (N) was completely dominant to the cretin (n), 

 and fertility {F) of the anthers was of course dominant to sterility (/). 

 We may draw attention to the fact that the crosses were in all cases of 

 the nature N/x nF, one of the two factors entering with each gamete. 

 In the following year a single F., family was raised and consisted of 51 

 normal fertile, 30 normal sterile, 33 cretin fertile, and 1 cretin sterile'. 

 The cretin character behaveil as recessive to the normal flower, but the 



' In this family and in one of those grown later both light and dark axilled plants 

 occurred. In each case the dark axil went in from the fertile cretin parent, and in F, 

 there is some coupling between the dark axil and fertility. The numerical result-s however 

 are complex and must be left over for discussion until more material is available. 



