J. J. Simpson 
217 
the perianth is concerned solely in the protection of the flower in the bud, but 
the corolla, in the open flower, also serves, along with the honey-secreting sacs at 
the base of the stamens, as an attraction for insects. 
The characters which have been taken as a basis for this study are numerical, 
e.g. the number of petals in the corolla, but no measurable characters, e.g. the 
length and breadth of the petals, have been considered, although, as will be pointed 
out later in connection with possible future studies in this flower, these characters 
might also with advantage be taken. 
The Cruciferaj, as an order, are usually regarded by botanists as being very 
definite in type and no observations have been recorded to show to what extent, 
if any, deviation from the recognised botanical floral formula exists, so that the 
main object of this pa,per was to determine the frequency of the variability of 
the parts of the various organs and constituents, and also the degrees of correlation 
existing between the organs themselves. 
The mode of observation is worthy of remark, however, as it might well be 
argued that if the flowers used for examination were fully "blown" deficiency in 
the number of parts might be due to post-developmental fracture, but in all the 
cases here recorded the observations were made on flowers in bud or only half open 
so that the influence of wind or other external agency is altogether discounted. 
The material was also examined micioscopically in all cases so that there should 
be no possible doubt as to the exact origin of any member. The importance of 
this will be seen in the details of the analysis. 
II. Botanical. 
1. Specific characters. 
The generic and specific characters of Lepiclium Draba may be obtained in any 
complete systematic botanical work so that it is unnecessary to repeat them here, 
but a few notes bearing especially on the study in hand may be of value. 
It is a perennial about a foot in height and is covered by a minute down from 
which its popular name, the hoary cress, is derived. The inflorescence is a raceme 
not much lengthened and so forms a broad, almost flat, corymb-like termination. 
The individual flowers are small, white and numerous. The constituents of calyx, 
namely the sepals, are green ; they are short, nearly equal and bear no pouch at 
the base. The petals are small and white ; they are equal in size, obovate, 
undivided and generally stalked. The stamens are six in number ; the filament 
is simple, i.e. it bears no appendages, and is shorter than the petals; the anther 
consists of two roundish lobes. The pods are "broader than long"; they are com- 
pressed laterally at right angles to the narrow partition. The thick valves are 
boat-shaped and sharply keeled but not winged ; each valve contains a single seed. 
