40 GENERAL REVIEW OF THE ORCHIDE.K. 



part of tlie (lower ; but in course of growth the ovary hecomes twisted, 

 so that in the adult condition we generally find the lip occupying the 

 lowi'r part of the Ihjwcr. In sonic cases, ])isa, Satyriuni, etc., tlie twist 

 does not take place, and the lip remains at the up[)('r i)art.* 



Displacement of one or more of the several meml)ers of the flower 

 is very common ; thus we find sepals taking the place of petals, and 

 petals of sepals, and it is noteworthy that when an organ is so 

 changed in position it is frequently changed in form and appearance 

 also. A petal occupying the position of a sepal for instance will 

 become like the sepal in form and colour, and is only to he distinguished 

 by following the coiu'se of its development and the arrangement of 

 its vascular bundles. A passage from the ordinary Avhorled to a spiral 

 disposition of the floral parts is also not uncommon. 



The woodcut. Fig. 1, illustrates displacement of parts in a flower 

 of Cupr/pcHinj/ x Morr/anio', in which the connate lateral sepals, one 

 petal, the lip and the column were normal. The peculiarity occurred in 

 the upper segment of the flower, which took the position of the 

 upper sepal, but which in appearance was partly sepal, partly petal. It 

 was not possible to trace its erratic course during development, but it 

 may be assumed that the upper sepal was not developed and that the 

 upper segment was a lateral petal displaced, assuming in part the 

 guise of a sepal as well as its position. 



Other changes might be mentioned, ]>ut these are suificient for the 



present purpose. It must, however, be carefully borne in mind that 



these changes rarely, if ever, occur separately but almost always in 



combination with others, and that an alteration in one part of a 



flower entails a corresponding change often of an opposite character as 



if l)y way of compensation. 



After these general indications, applicable to the flower as a whole, 



I may now briefly advert to some of the principal or most frequent 



deviations met with in the several parts or whorls of the flower 



considered separately. 



Outer roil- of perianih seijmentx — Calyx. The changes that occur in 

 the calyx (sepals) are usually of no great moment. Alterations of 

 relative size are not infrequent, and a not unconnnon change in some 

 species of Oncidium is the reduction of the sepal to a mere thread, 

 owing to the development of the midrib and to the concurrent 

 arrest or su])pression of the lateral portions of the segment. (This 

 occurs normally in On. ahortivum and On. heferanthuni.) Theoretically the 

 three outer segments should be distinct and separate, but we sometimes 



* Mr. Douglas, of Ilford, Essex, not long t.ince sent to the writer a very ciuions two-flowered 

 inflorescence of Gypripcdium caudatum, in wliich one flower had the lip nj)peiraost, while 

 in the other it occupied its normal position ; tlie position of the other segments being 

 correspondingly altered. 



