IN PLANTS HAVING IRREGULAR COROLLAS. 405 
From examination of the figures given it will be readily seen 
that the flowers of both the types stand, when expanded, so that 
the median plane of their symmetry is vertical, and this position 
is gradually assumed as the flower matures. The period at which 
it is determined upon which plan the flower shall develop has not 
been ascertained, but there is little doubt that this occurs early 
in the formation of the bud, for examination of buds which were 
only just coloured showed that they were already formed upon 
one or other of the two types. 
Flowers intermediate between the two types.—It has been re- 
marked above that, of whichever type a flower may be, it never- 
theless stands in sucha manner that the middle plane of its 
symmetry is vertical. There are, however, flowers which are 
formed neither upon the one type nor on the other, and these 
flowers stand in a position which is intermediate between those 
assumed by flowers of the two types respectively. Among the 
very large number of specimens examined at Mr. Burrell’s 
nursery, intermediate flowers were decidedly uncommon ; but if 
an intermediate flower was found on a spike, it was usual for 
Several other flowers on the same spike to be also of the inter- 
mediate form. A reference to the figures will at once show the 
characters of such intermediate flowers. The first type is charac- 
terized by the possession of two modified anterior segments of 
the inner whorl, while the second type has only one such modified 
Segment in the inner whorl; but in the intermediate forms, one 
Segment is as a rule fully modified both in form and colouring, 
while an adjacent segment of the inner whorl, which, if the 
flowers were of the first type, would have been similarly modified, 
is only partially thus ditfereutiated, being intermediate in size 
and markings between the fully modified and reduced anterior 
Segment and the large and unmodified posterior segment. It 
appeared that the correlation between the reduction in size and 
the alteration of colour in these anterior segments is very close ; 
for in proportion as the size of the segment is increased from 
the narrow form of the marked petal, so does the extent and 
intensity of the marking dimiuish. In a number of cases it 
was seen that the position taken by an intermediate flower is 
such that the reduced and marked petal (fig. 4, 2) comes to lie 
more nearly in the anterior middle line than it would do were the 
flower of the first type, but it does not lie actually in the middle 
anterior line, as it would do were the flower of the second type, 
