74 



Evolution of the Double Stock 



thu other two being hidden. The monstrous gynoecium resulting from 

 the twin ovaries appeared to have 5 stigma lobes. In Fig. 3 taken 

 from a flower in the same position on a lateral axis of a third plant (0) the 



twin nature of the gynoecium is seen at a 

 very much later stage. In the case of plant 

 A, the only one examined for this point, 

 the pedicel was somewhat thicker than 

 usual and showed, on cross section, an ellipti- 

 cal instead of the normal ring arrangement 

 of the fibro-vascular bundles, characteristic 

 of the true double as well as the single. 

 The stouter form of the pedicel can be de- 

 tected in Sowerby's drawing (second flower) 

 and though slight, the increase is no doubt 

 faithfully portrayed. The fact that the twin 

 flowers appear to develope from a common 

 basis accounts for the incomplete duplica- 

 tion of the parts on the adaxial sides. We 

 get no indication from Sowerby's figure 

 (owing to the view presented) of the com- 

 position of the calyx and gynoecium of the 

 second flower, but if my interpretation is 

 correct we have here a case of twinning 

 carried to a further stage, combined, ap- 

 parently, with petalody of at least one 

 member of the androecium. We may include in the same category no 

 doubt the case observed by Master's^ and described under the head of 

 synanthy^ Here duplication of calyx, corolla and androecium was all but 

 complete, only the two short stamens at the point where separation 

 was imperfect being suppressed. We may then I think conclude, not- 

 withstanding the statements of various writers which might be inter- 

 preted to the contrary, that there is no case on record of a genuine semi- 

 double Stock ; and that the records in question owe their origin to the 

 occasional occurrence of more or less perfect " twinning " of the lowest 

 flowers on the earliest flowering axes. 



I wish, in conclusion, to express my grateful thanks to Miss D. F. M. 

 Pertz who kindly made the drawings from my plants. 



1 Vegetable Teratology, p. 38, 1869. 



2 I have intentionally refrained from using this term in the present instance in order to 

 avoid the implication that in the normal condition there are two distinct flowers which 

 become occasionally more or less fused together. 



Fig. 3. Nearly mature fruit from 

 the lowest "flower " on the first 

 lateral branch of a third plant C 

 (much foreshortened). A dis- 

 tinct furrow occurs on both sides 

 in the dividing plane. 



