198 Observation of the Qjrigin of I 'arieties. 
I refer to a very beautiful instance of the latter (Fig. 36) 
which I owe to the kindness of MR. ERNST H. KRELAGE 
in Haarlem. 
The origin of double flowers in other groups of flow- 
ering plants has probably occurred on similar lines with 
that of double inflorescences. I restrict myself to a con- 
sideration of doubling by the transformation of stamens 
into petals, that is, the petalocly of the stamens, referring 
the reader for an account of the other types of doubling 
to GOEBEL'S well-known monograph. 1 
Occasional petaloid stamens occur fairly commonly 
both in culture and in nature ; they are so well known 
that it is not necessary to cite special instances. The 
curve which represents this variation is unilateral, indi- 
cating thereby the existence of a latent or semi-latent 
character. 2 The attempt to render this active may be 
made, and if it succeeds 3 the origin of a double variety 
may be expected. 
Double varieties of this kind tend to vary in the same 
way as those of composites. If, for instance, the com- 
mercial Varictatcs plcnac of Clarkia pulchclla, Clarkia 
clcyans. Phlox Drummondi and others are examined, 
almost all the intermediate stages between nearly hemi- 
spherical double flowers and flowers with normal sta- 
mens are met with. In such cases it is usually obvious 
that favorable conditions tend to increase "doubling," 
a fact which has been known for a long time in the 
case of Anthemls nobilis, of some species of Narcissus, 
1 K. GOEBEL, Bcitragc zur Kcnnhu'ss gcfiilltcr Bliithcn, in PRINGS- 
HEIM'S Jahrb. f. wiss. Bot, Vol. 17, 1886, p. 207. 
2 Ucbcr halbc Galton-Curvcn ah Zeichcn discontimurlichcr l r aria- 
tion. Ber. d. d. hot. Ges., Vol. XII, 1894, p. 197. 
3 Which is, however, by no means always the case. See the ex- 
periment with Ranunculus bulbosus in 23 of this part. 
