REPRODUCTIVE ORGANS IN THE PRIMULACER. 123 
clearly shown by the relatively increased percentage of seeds 
resulting from the latter conjunctions. This relative increase 
in the percentage of seeds by the reciprocal unions, though 
certainly much under those usually resulting from a comparison 
of the homomorphie and heteromorphie unions of Primulas, is 
nevertheless sufficient to affect importantly the number of the 
individual representatives ; and this the more especially if, as 
Mr. Darwin forcibly urges, close-breeding has a tendency to 
weaken the progeny. 
Connected with these functional peculiarities there is another 
point worthy of a passing notice—namely, the variability in the 
length of the pistil. As I have previously stated, this organ is 
generally of an equal length with the stamens ; occasionally, how- 
ever, flowers occur in which the stigmas rise above the stamens 
and project beyond the mouth of the corolla-tube; and again» 
there are others in which it does not even reach the stamens, 
while the latter in every case observed by me retain a definite 
position around the mouth of the corolla-tube. The intimate 
systematic affinities, already alluded to, of the present species 
with the P. floribunda give the above variabilities an additional 
interest* In respect to the latter species we have stated that 
along with normally short-styled plants, others occur in which the 
stamens and pistils are of an equal length. Guided by analogy, 
then, we may suppose that as the P. floribunda has not as yet, 
attained the, at least provisional, equilibrium of dimorphism, as 
shown by a percentage of non-dimorphic forms, so these func- 
tional and structural peculiarities of the P. verticillata are pre- 
sumptive indications of an ulterior dimorphic tendency. 
Summary.—The species of Primula are variously estimated by 
authors, many of the, forms reputed specific by one being con- 
sidered as mere varieties by another. Steudel, for example, in 
his * Enumeratio Plantarum, admits 85 species, whereas DeCan- 
dolle (* Prodromus’). gives only 61—a difference of 24 doubtful 
forms. Of these varieties or species, then, I have given the 
sexual characteristics of 54:—36 of which are truly dimorphic, 
presenting both long- and short-styled forms; 13 in which the 
long- or short-styled forms, respectively, have alone been ob- 
served by me; and 5 species and one variety with non-dimorphic 
characteristics, i.e. presenting stamens and pistils of an equal 
length. 
The allied genera Hottonia and Aretia have also truly dimorphic 
species ; whereas other allied genera—Dodecatheon, Soldanella, and 
LINN. PROC.—BOTANY, VOL. VIII. L 
