PREFACE. XX111 



me, by letter, with the following particulars concerning 

 the origin of this fine hybrid. " Our C.purpureo-elongatus 

 was produced from our own sowing, but not by means 

 of artificial fertilisation ; the mother of this plant is C. 

 elongatus, from which we gathered the seeds ; but near 

 this stood a C. purpureus, and probably the hybrid was 

 produced by insects conveying the pollen from the latter 

 plant to the former. We have never observed in this 

 plant such a change of form as occurs in C. Adami." 

 After all this, we look with so much the greater impa- 

 tience for positive elucidation, based on repeated experi- 

 ments, of the mode of origin of C. Adami, and in this 

 for the establishment of several most important physiolo- 

 gical facts. In regard to the return of Cytisus Laburnum 

 quercifolius, into the common Laburnum with entire 

 leaflets, mentioned at p. 315, I shall only mention here, 

 in addition, that I have observed the same phenomenon 

 lately in the Botanic garden of this town, and here the 

 transition to the parent species took place by a marked 

 separation from the variety and not through graduated 

 intermediate stages. 



Since this Preface is at the same time a Postscript, and 

 as regards the first part of the Treatise a tolerably late one, 

 it affords an opportunity of adding a few more comple- 

 mentary observations on the subjects touched upon in 

 the text. In the first place, in regard to the mode of growth 

 of the Vine, described at p. 46, I must report that the 

 examination of fresh seedlings obtained last autumn, after 

 that passage had been printed, did not confirm the con- 

 jecture expressed in the note, that the seedlings would 

 behave like root-suckers ; for they were totally devoid of 

 tendrils at the summit, and displayed in the axils of the 



