[388]

Tomato dark

Horizontal glass

Oct 24'

Nutation of axis

Solanum lycopersicum

[data not transcribed]

(used)

[388v]

(49A 54

Ch. 8

*(24) Footnote to p. 49

In some other members of the Duck Family the speculum in the two sexes differs in a greater degree, but I have not been able to discover whether its full development occurs later in life in the males of such species than in the male of the common duck, as ought to be the case according to our rule.

With the allied Mergus cucullatus we have however a case of their kind: the two sexes differ conspicuously in general plumage, & to a considerable degree in the speculum, which is pure white in the male, & greyish-white in the female. Now the young males at first resemble in all respects the female & have a greyish-white speculum; but this became pure white before the other more strongly marked sexual difference in plumage are required by thr adult male: see Audubon, Ornithological biography vol. III 1835 p 249-250.─

[Descent 1: 291, n29: "In some other species of the Duck Family the speculum in the two sexes differs in a greater degree; but I have not been able to discover whether its full development occurs later in life in the males of such species, than in the male of the common duck, as ought to be the case according to our rule. With the allied Mergus cucullatus we have, however, a case of this kind: the two sexes differ conspicuously in general plumage, and to a considerable degree in the speculum, which is pure white in the male and greyish-white in the female. Now the young males at first resemble, in all respects, the female, and have a greyish-white speculum, but this becomes pure white at an earlier age than that at which the adult male acquires his other more strongly-marked sexual differences in plumage: see Audubon, 'Ornithological Biography,' vol. iii. 1835, p. 249-250."]