an anterior position.’’ In my use of the term I have ig- 
nored the mechanical means by which the position of the 
labellum may be effected and have employed resupina- 
tion whenever the labellum is visually the lowermost seg- 
ment of the orchid flower. 
As far back as Christian Konrad Sprengel’s time, one 
hundred and forty-five years ago, the relation of the la- 
bellum of the orchid to pollination was understood ; in- 
deed, Sprengel was one of the first naturalists to empha- 
size this by pictorial means. On the quaint- 
ly adorned title-page of his Das entdeckte 
Geheimnis der Natur im Bau und in der 
Befruchtung der Blumen published in Ber- 
lin in 1798, he introduced a flower of Las- 
tera ovata with an insect on the labellum, 
its head in contact with the pollinia. But 
why the labellum of the orchid should have 
developed adaxially and then should have 
become the lowermost perianth segment by 
a half-twist and by curvature of the ovary is a biological 
mystery surrounding the effects of symbiosis. 
Perhaps this mystery is intensified by Malaais palu- 
dosa, a species with the labellum constituting the upper- 
most member of the perianth. To the casual observer the 
labellum of M. paludosa appears to be quite normally 
placed and as yet uninfluenced by the forces that cause 
resupination. Charles Darwin, in his lighter studies,’ ex- 
amined the flowers of this orchid and found that the po- 
sition of the labellum is remarkable because it has been 
‘purposely acquired’’ as shown by the ‘‘ovary’’’ being 
‘In a letter to Sir J. D. Hooker, Darwin wrote in 1861; “‘What 
frightful trouble you have taken about Vanilla; you really must not 
take an atom more; for the orchids are more play than real work.”’ 
? From my observations made on herbarium specimens I am of the 
opinion that the so-called twist is confined to the pedicel. Colonel 
M. J. Godfery is also of this opinion and in a letter has informed me 
that ‘‘the ovary itself is not twisted and is scarcely longer than its 
twisted stalk.” 
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