canthinae, it invariably anastomoses with those of the 
adjacent lateral petal. 
Another feature to be noted is the origin of the mar- 
ginal traces of the adjacent perianth lobes. Usually the 
marginal traces of the outer perianth members are de- 
rived from the traces underlying the perianth members 
of the inner whorl or vice versa. 
Comparative Résumé of the Vascular Supply 
of the Stamens 
A lack of proper understanding of the vasculature of 
the staminal whorls, in the past, seems to have been the 
cause of the confusion prevailing today with regard to 
the exact composition of the androecium of orchids. In 
this connection two points need clarification, —(A) the 
number of staminal traces that are given off and their 
identity, and (B) the method by which a simple origin 
becomes increasingly complicated through the interven- 
tion of adnation. It is difficult to separate the two as- 
pects which are so closely associated in orchids; but for 
the sake of convenience of description, I propose to treat 
the two points under the headings (A) and (B), as men- 
tioned above. 
A. It has already been pointed out that in the Cypri- 
pedilinae the two lateral stamens of the inner whorl! (al 
and a2) are functional and that the median stamen of the 
outer whorl (A1) is externally represented by a stami- 
node, which also receives a vascular trace. Furthermore, it 
has also been mentioned that in the monandrous orchids 
it is the median stamen of the outer whorl (A1) that is 
functional and that quite often the lateral stamens of the 
inner whorl (al and a2) are represented only by vascular 
traces. ‘The presence or absence of the traces cannot be 
made out by any external morphological distinctions. 
eae 
