CHAP. V LATHYRUS ODOBATUS. 155 



cannot have intercrossed. What does occasionally occtir is that 

 in a row of plants raised from seeds of one variety, another 

 variety true of its kind appears ; for instance, in a long row of 

 Scarlets (the seeds of which had been carefully gathered from 

 Scarlets for the sake of this experiment) two Purples and one 

 Painted Lady appeared. Seeds from these three aberrant plants 

 were saved and sown in separate beds. The seedlings from both 

 the Purples were chiefly Purples, but with some Painted Ladies 

 and some Scarlets. The seedlings from the aberrant Painted 

 Lady were chiefly Painted Ladies with some Scarlets. Each 

 variety, whatever its parentage may have been, retained all its 

 characters perfect, and there was no streaking or blotching of 

 the colours, as in the foregoing plants of crossed origin. Another 

 variety, however, is often sold, which is striped and blotched 

 with dark purple ; and this is probably of crossed origin, for I 

 found, as well as Mr. Masters, that it did not transmit its 

 characters at all truly. 



From the evidence now given, we may conclude that the 

 varieties of the sweet^pea rarely or never intercross in this 

 country ; and this is a highly remarkable fact, considering, firstly, 

 the general structure of the flowers ; secondly, the large quantity 

 of pollen produced, far more than is requisite for self-fertilisation ; 

 and thirdly, the occasional visits of insects. That insects should 

 sometimes fail to cross-fertilise the flowers is intelligible, for I 

 have thrice seen humble-bees of two kinds, as well as hive-bees, 

 sucking the nectar, and they did not depress the keel-petals so 

 as to expose the anthers and stigma ; they were therefore quite 

 inefficient for fertilising the flowers. One of these bees, namely, 

 Bomlus lapidarius, stood on one side at the base of the standard 

 and inserted its proboscis beneath the single separate stamen, as 

 I afterwards ascertained by opening the flower and finding this 

 stamen prised up. Bees are forced to act in this manner from 

 the slit in the staminal tube being closely covered by the broad 

 membranous margin of the single stamen, and from the tube 

 not being perforated by nectar-passages. On the other hand, 

 in the three British species of Lathyrus which I have examined, 

 and in the allied genus Vicia, two nectar-passages are present. 

 Therefore British bees might well be puzzled how to act in 

 the case of the sweet-pea. I may add that the staminal tube 

 of another exotic species, Lathyrus grandijlorus, is not per- 

 forated by nectar-passages, and this species has rarely set any 

 pods in my garden, unless the wing-petals were moved up and 



