Chap. VIII. WHEN CROSSED. 059 



each oilier in his r.arclcn ; and although these j)lants liavc 

 separated sexes, they never naturally crossed. lie then fertil- 

 ized thirteen flowers of the one with the pollen of the other; 

 but only a sing-le head jiroduced any seed, and this one head 

 produced onl}' live j^rains. Manipulation in this case could not 

 have l)een injurious, as the plants have separated sexes. No 

 one, I believe, has suspected that these varieties of maize arc 

 distinct species; and it is important to notice that the hybrid 

 plants thus raised were themselves j^erfecthj fertile ; so that 

 even Gartner did not venture to consider the two varieties as 

 specilically distinct. 



Girou do Buzareingues crossed three varieties of gourd, 

 which, like the maize, has separated sexes, and he asserts that 

 their mutual fertilization is by so much the less easy as their 

 differences are greater. How far these experiments may be 

 trusted, I know not ; but the forms experimented on are 

 rapked by Sageret, who mainly founds his classification by the 

 test of infertility, as varieties; and Naudin has come to the 

 same conclusion. 



The following case is far more remarkable, and seems at 

 fh-st quite incredible ; but it is the result of an astonishing 

 number of experiments made during many years on nine spe- 

 cies of Verbascmn, by so good an observer and so hostile a 

 witness as Gartner; namely, that the yellow and white varie- 

 ties when crossed i)roduce less seed than the similarly-colored 

 varic;ties of the same species. Moreover, he asserts that, when 

 yellow and white varieties of one species are crossed with yel- 

 \o\v and white varieties of a distinct species, more seed is pro- 

 duced by the crosses between the similarly-colored flowers 

 than between those which are diflerently colored. ]\lr. Scott, 

 also, has experimented on the species and varieties of Verbas- 

 cum ; and, although unable to ctrnfinn Gartner's results on the 

 crossing of the distinct species, he finds that the dissimilarly- 

 colored varieties of the same species yield fewer seeds, in the 

 proportion of 8G to 100, than the similarly-colored varieties, 

 ^'et these varieties difl'er in no respect, except in the color of 

 their flowers; and one variety can sometimes be raised from 

 the seed of another. 



Kolrcuter, whose accuracy has been confirmed by every 

 subscijucnt observer, has proved th(» remarkal)le fact that one 

 particular variety of the connnon tobacco was more fertile than 

 the other variiMies, when cro.ssed with a widely-distinct species. 

 He experimented on live fonns, which are commonly reputed 



