in the Stock {Mat thiol a incana). 465 
the past. For there can he no doubt that in all these cases we are witnessing 
the reappearance of an ancestral character exhibited to a very slight degree 
and only sporadically in the several genera cited above (see foot-note, p. 464), 
bitt here manifested to a remarkable extent . These occurrences, in fact, 
furnish concrete evidence that the progenitors of the present-day type of 
Crucifer were possessed of a many-carpelled ovary, and thus approached 
more nearly to the construction of some existing types among the Papa- 
veraceae. Before leaving this part of the subject, it may be well to empha¬ 
size the point that the conception of two kinds of carpels is essential to the 
understanding of the relation of these multicarpellary fruits to the typical 
siliqua, and of the arrangement and position of the valves, especially in 
3-valved fruits, in which the unpaired valve is generally lateral, though 
occasionally median. In the former case the suppression or consolidation 
of one lateral valve has been balanced by the production of hollow instead 
of solid carpels in the diagonal planes on that side. Similarly, in the latter 
case the development of one valve in the median plane has been com¬ 
pensated by the consolidation of the lateral carpels and the assumption of 
valve form by the two carpels in the diagonal planes. Several observers 
who have declared their adherence to the G 2 formula for the typical siliqua 
nevertheless cite these exceptional fruits as having a phylogenetic signi¬ 
ficance and as evidence of a fuller ground-plan composed of four orthogonal 
valve carpels. It is perhaps the contradiction involved in this position—for 
such a ground-plan does not satisfactorily account for the 3-valved siliqua 
—which has delayed recognition of the real character of these fruits now 
shown to be derived from a 4 + 4 ground-plan, and has caused them to be 
dismissed as ‘ sports ’ or monstrosities. On the other hand, Lindley, Kunth, 
and Klein, who recognized the commissures to be carpels, for whatever 
cause, do not appear to have extended their observations to these multi¬ 
carpellary ovaries. How many cases of so-called ‘ sports ’ appearing under 
cultivation, or as the result of some other change in the external environ¬ 
ment, are in reality the expression of some ancestral phase reappearing 
under a favourable combination of circumstances is a question which needs 
further investigation. 
But the dimorphic nature of the carpel does more than rehabilitate 
the septum ; it removes that most crucial difficulty, the commissural stigma. 
Observation shows that in the great majority of the Cruciferae the valve 
carpels have ceased to fulfil the receptive as well as the reproductive 
plant (Animals and Plants, p. 381). Instances are also recorded by Godron (loc. cit., p. 303) for 
Brassica oleracea, L., by Eichler (Flora, 1872, p. 333) for Brassica Nagies, by Wille (Bot. Centralbl., 
xxvi, 1886, p. 121) for Capsella Bursa-pastoris , L., and figured by Schnizlein (Iconographia, 
Fig. 181 a, Figs. 39, 40) for Raphanus. The difference in orientation of multicarpellary fruits arising 
from this cause which show isobilateral symmetry, from those due to reversion which are constructed 
on a radially symmetrical plan, is illustrated in Godron’s figures of Brassica oleracea. (Compare 
Figs. 1 and 2 with Figs. 6 and 7, PI. XVIII, loc. cit.) 
