398 ON THE DIRECT ACTION OF THE Chap X I , 



the Tall Sugar-pea, which bears very thin green pods, becoming brownish- \/ld ^l 



white when dry, with pollen of the Purple-podded pea, which, as its name 

 expresses, has dark-purple pods with very thick skin, becoming p a i e 

 reddish-purple when dry. Mr. Laxton has cultivated the tall sngar-p ea 

 during twenty years, and has never seen or heard of it producing a purple 

 pod; nevertheless, a flower fertilised by pollen from the purple-pod yielded 

 a pod clouded with purplish-red, which Mr. Laxton kindly gave to me. 

 A space of about two inches in length towards the extremity of the pod, 

 and a smaller space near the stalk, were thus coloured. On comparing the 

 colour with that of the purple-pod, both pods having been first dried and 

 then soaked in water, it was found to be identically the same ; and in both 

 the colour was confined to the cells lying immediately beneath the outer 

 skin of the pod. The valves of the crossed pod were also decidedly thicker 

 and stronger than those of the pods of the mother-plant, but this may 

 have been an accidental circumstance, for I know not how far their thick- 

 ness in the Tall Sugar-pea is a variable character. 



The peas of the Tall Sugar-pea, when dry, are pale greenish-brown, thickly 

 covered with dots of dark purple so minute as to be visible only through a 

 lens, and Mr. Laxton has never seen or heard of this variety producing a 

 purple pea ; but in the crossed pod one of the peas was of a uniform beau- 

 tiful violet-purple tint, and a second was irregularly clouded with pale 

 purple. The colour lies in the outer of the two coats which surround the 

 pea. As the peas of the purple-podded variety when dry are of a pale 

 greenish-buff, it would at first appear that this remarkable change of colour 

 in the peas in the crossed pod could not have been caused by the direct 

 action of the pollen of the purple-pod : but when we bear in mind that 

 this latter variety has purple flowers, purple marks on its stipules, and 

 purple pods ; and that the Tall Sugar-pea likewise has purple flowers and 

 stipules, and microscopically minute purple dots on the peas, we can hardly 

 doubt that the tendency to the production of purple in both parents has 

 in combination modified the colour of the peas in the crossed pod. 

 After having examined these specimens, I crossed the same two varieties, 

 and the peas in one pod, but not the pods themselves, were clouded and 

 tinted with purplish-red in a much more conspicuous manner than the peas 

 in the uncrossed pods produced at the same time by the same plants. I may 

 notice as a caution that Mr. Laxton sent me various other crossed peas 

 slightly, or even greatly, modified in colour; but the change in these 

 cases was due, as had been suspected by Mr. Laxton, to the altered colour 

 of the cotyledons, seen through the transparent coats of the peas; and 

 as the cotyledons are parts of the embryo, these cases are not in any way 

 remarkable. 



Turning now to the genus Matthiola. The pollen of one kind of stock 

 sometimes affects the colour of the seeds of another kind, used as the 

 mother-plant. I give the following case the more readily, as Gartner 

 doubted similar statements with respect to the stock previously made 

 by other observers. A well-known horticulturist, Major Trevor Clarke, 

 informs me 120 that the seeds of the large red-flowered biennial stock 



120 See. also a paper by this observer, read before the International Hort. and isi^du 



Bot. Congress of London, 1866. h Nsact 



