124 MR. J. SCOTT ON THE FUNCTIONS AND STRUCTURE OF THE 
Cortusa—are very generally characterized by species presenting 
the structural characteristics of the long-styled form only, without, 
however, any decreased fertility arising from their hermaphrodite 
conjunctions. 
The general differences of the two sexual forms may be thus 
briefly summed up :—First, the long-styled forms have pistils 
equalling in length the tube of the corolla; stigmas usually larger 
and rougher; stamens attached to, or frequently below the middle 
of the corolla-tube, whose diameter is thus expanded upwards; 
pollen-grains generally smaller and more transparent. Secondly, 
in the short-styled form the pistil is short, not rising above halfway 
up the corolla-tube ; stigma generally smoother and depressed on 
the summit; stamens attached to the mouth of the corolla-tube, 
causing an abrupt expansion; pollen-grains generally larger and 
more opaque. According to all the trials, these structural differ- 
ences are accompanied by equally remarkable functional differences, 
—the pollen of the long stamens being alone adapted to fertilize 
the long pistils, and the pollen of the short stamens to fertilize 
the short pistils. By applying, on the other hand, either form 
pollen to own form stigma, i. e. effecting a homomorphie union, 
the degree of fertility relatively to the above, or heterömorphie 
union, is greatly decreased. Analogous, though less striking, 
functional differences, however, oceur without any appreciable 
change of structure, as shown by the P. verticillata, e. g., yielding 
a much higher grade of fertility by its dieeious than its herma- 
phrodite conjunctions. Such an instance from a genus whose 
members are so generally characterized by a sexual dimorphism, 
naturally leads me to regard it as indicative of the acquirement 
of similar characteristics. An objection to this view may be urged 
from the occurrence of species which, having*no immediate affinity 
with any structurally dimorphic species, nevertheless present indi- 
viduals incapable of fertilization by own pollen, though perfectly 
susceptible to reciprocal fertilization, either with another indi- 
vidual of the same species, or one of a distinct species. To this 
category, at least, those who disbelieve in the genetic affinities of 
organic beings will no doubt refer the case of P. verticillata, and 
simply regard it as further illustrative of our ignorance of the 
conditions upon which sterility, in its varied grades, depends. 
Those, on the other hand, who believe in the existence of these 
genetic relations will look with an intelligent interest upon these 
functional peculiarities of the P. verticillata, and regard them, 
mayhap, as the primary indications of a tendency to assume those 
