Notes. 629 
developed, and some or all exserted ; neither form appears to seed 
habitually.) 
The pistil in some species is very constant, while in others it shows 
all stages of cohesion and reduction to two carpels, this being the 
almost invariable number in certain species. Abortion is less frequent, 
and complete suppression cannot be distinguished from complete 
cohesion. Chorisis is very frequent in aviculare and some other 
species, in all degrees from a mere enlargement of one or more 
stigmas to an increase in number (up to seven), with corresponding 
modifications in structure in the ovary. Only one ovule has been 
observed in each ovary. 
Markedly teratological forms have been met with, but are not 
included in this summary. 
No very definite relation has been traced between the position of 
a flower on the axis and deviations in structure, though pressure tends 
to abortion or suppression of parts, especially of the sexual organs. 
(The flowers examined have chiefly been those sufficiently open to 
allow the natural arrangement to be noted without manipulation, to 
avoid displacement of parts, hence cleistogamous flowers are scarcely 
included.) The variability appears rather to express the result of an 
innate tendency to vary where not subject to the check of loss of 
fertility, the variations in Polygonum not leading to this loss. 
The same number of parts in a whorl may be due to very different 
causes, and still more may the same number of stamens express very 
different arrangements in the flower ; hence such a statement in 
a specific description as ‘ stamens usually six ’ is insufficient. 
J. W. IT TRAIL, 
