J. J. Simpson 
257 
VII. Suggestions for Future Studies in this Plant. 
It must be very obvious to anyone who has perused this paper that the results 
which might be obtained from a study of this plant are by no means exhausted. 
An attempt, however, has been made to interpret the variability in its flowers, 
both from a morphological and an evolutionary standpoint. Studies of a different 
nature might be undertaken in order to test the results obtained, e.g. : 
(1) What is the degree of fertility in the flowers of this plant? For this 
purpose it would be necessary to find the percentage of flowers which produce 
fertile seed. 
(2) What are the variants, if any, which are associated with infertility ? 
(3) What are the characters of the flowers which are produced from the seeds 
of the different variants ? If seeds selected from the different variants were grown 
separately and self-fertilised, one could trace the valuations in the flowers of the 
next generation and see to what extent the different variations were transmitted. 
This study is capable of much elaboration and is one which would be fraught with 
great possibilities. It seems to involve a satisfactory metliod of determining how 
far these variations are concerned in plant economics, and also to what extent 
they have been instrumental in the evolution of the Order Cruciferai. 
EXPLANATION OF FIGURES 8, 9 AND 10. PLATE I. 
FIGURE 8. 
(a) Typical stamen (outer whorl). 
(b) Stamen with half-length filament and complete anther (outer whorl). 
(c) Typical stamen (inner whorl). 
(d) Non-cborised stamen with two complete anthers (inner whorl). 
(e) Stamen of inner whorl with two complete anthers but only chorised in the upper half. 
FIGURE 9. 
(a) Aborted stamen of outer whorl, i.e. filament with no anther. 
(b) Absence of stamen in outer whorl. 
(c) Full-length filament in inner wliorl with no anther. 
(d) Half-length filament in inner whorl with complete anther. 
(e) Half-length filament in inner whorl with no anther. 
(/) Non-cborised stamen in inner whorl with half-length filament but with two complete anthers. 
FIGURE 10. 
(a) Normal sepal. 
{h) Sepal divided almost to the very base. 
(c) Sepal completely divided into two distinct sepals. 
{d) Sepal absent. 
(e) Normal petal. 
(/) Petal divided almost to the very base. 
ig) Aborted petal. 
(/() Petal absent. 
