262 



PLANT HYBRIDIZATION BEFORE MENDEL 



had been allowed to scatter, and the seedlings to grow wherever 

 they chanced to appear. 



"I had already," he says, "remarked a singularity in the general ap- 

 pearance of one of these, and was watching the expansion of its flow- 

 ers, when I was agreeably surprised to find it a decided hybrid, obviously 

 having most of its characters exactly intermediate between those of pur- 

 purea and lutea. [p. 258.] . . . My plant exactly agrees in most particu- 

 lars with a hybrid procured by Kolreuter in 1768, from seeds of lutea fer- 

 tilized by the pollen of purpurea. (Acad. Petropol. Anno. 1777.)" 



In general habit, Henslow's hybrid is stated to have approached 

 "much nearer lutea than purpurea^ (p. 258.) 



"It is, however," he continues, "decidedly taller and more robust than 

 any specimens of the former species which my garden ever produced. 

 Kolreuter indeed asserts that the specimens raised by him were taller than 

 either of their parents, but he assigns a lower limit to the height of 

 purpurea than that to which many plants of this species have attained 

 with me." 



On p. 258, Henslow gives an analysis of twenty-five characters 

 in root, stem, leaf, inflorescence, flower, stamens, and pistil, with 

 illustrative plates. 



"a single glance of the eye," he says, "will thus be sufficient to show 

 how totally intermediate most of its organs are, both in size and form, 

 and in some cases also in colour, to those of the two parents." (p. 259.) 



Attempts to fertilize the hybrid with its own pollen, as well 

 as with pollen of the two parents, failed, and the comment is made 

 that Kolreuter was similarly unsuccessful in his case. Some dis- 

 cussion is given as to whether hybrids are self-fertile or not. The 

 paper merits mention by reason of the fact that, if not the first, 

 it is one of the first attempts to present, in systematic detailed 

 form, a comparative study, in part microscopic, of the structures 

 in a hybrid and its two parents. A satisfactory scale is not given. 

 A few of the principal characters noted are given in the following 

 table : 



External Characters 



Root 



Height of stem 

 Length of raceme 

 Leaves 



D. purpurea 

 Biennial 



3 to 5 ft. 



\y2 in. to 3 ft. 



Woolly 



D. lutea 

 Bi-triennial 



2 ft. 



^ to 1 ^ ft. 



Glabrous 



Hybrid lutea X 

 purpurea 



Apparently peren- 

 nial 



About 3^ ft. 



About 1^ ft. 



Nearly smooth 

 above, quite 

 woolly below 



