492 
ORCHIDACEAE 
terms anterior and posterior, the resupination is supposed not to have 
occurred). 
The various organs face the labellum, and, if the fir. of a simple 
O., e.g. Orchis, be examined, they can easily be made out. A little 
above the base may be seen the two stigmas, then above these a pro- 
jecting point, the rostellum, and above this again, and behind it, 
forming the apex of the column, is the anther, which shows two lobes. 
Each of these is occupied by a pollinium, or mass of pollen. Under 
the microscope the grains of pollen are seen to be tied together in 
packets by elastic threads ; the threads unite at the base of the 
pollinium and form a cord, the caudicle , which runs down into, and is 
attached to part of the rostellum. 
The simple construction found in Orchis &c., as thus described, is 
replaced by much more complex arrangements in many sp. The 
labellum itself may be rendered very complex, by the addition of 
spurs and other outgrowths ; very often outgrowths of the summit of 
the receptacle take place, displacing some of the organs, thus for 
example in Drymoda and others, the labellum and the sepals on 
either side of it are carried forward on an axial protuberance in such 
a way that the sepals appear to spring from the labellum, the axial 
growth (chin) appearing like the basal part of this organ. Some of 
these constructions are very complex. Several are described in con- 
nection with the genera to which they belong, but for details refer- 
ence must be made to A T at. PJl. 
Similarly the column shows great variety in structure, for details 
of which refer as above. One point may be mentioned specially as of 
importance in classification. In the simple case of Orchis &c., 
described above, the base of the anther loculi is against the rostellum ; 
such cases are called basitonic; in others it is the apex that is next the 
rostellum (Oncidium, &c.), and these are acrotonic . 
[Diandrae. So far only monandrous forms have been con- 
sidered. In Cypripedium and its allies the column has 2 anthers, no 
rostellum, and a simple stigma, composed of the 3 carpellary stigmas. 
The two sta. belong to the inner whorl, and the sta. which in 
Monandrae is fertile, is here represented by a large staminode. The 
stigma is not sticky, but the pollen is, and it is not combined into 
pollinia.] 
The ovary is inferior in all O., unilocular with 3 parietal placentae 
(exc. Apostasia), and very numerous ovules, which do not develope 
until fertilisation of the fir. occurs. 
The adaptations of orchid flowers to fertilisation by insects are 
endless, and many very complicated. Reference must be made to text- 
books for the details. No student should omit to read Darwin’s 
Fertilisation of Orchids , at least the first two and the last chap- 
ters. In it will be found accounts of the mechanism of most of 
the common genera. A few general points only can be mentioned 
