DISPLACEMENT. 95 



occupies the place of a suppressed or abortive organ, 

 but frequently assumes its colour, and, to some extent, 

 its function. This has been alluded to in the case of 

 the leaf of Gesnera (see p. 88) and in Orchids this 

 replacement seems to be very common; thus, in 

 addition to the cases before mentioned, in a flower 

 of an Odontoglossum, for which I am indebted to 

 Professor Oliver, the two lateral sepals were united 

 together and occupied the position of the labellum, 

 which was absent. A similar occurrence happens 

 occasionally in Lycaste Shinne)% thus recalling the 

 structure of Mcisdevallia, where the labellum is normally 

 very small. The arrangement in Lycaste may thus 

 be symbolised : 



s 

 p st r 



+ 

 s s 



the + indicating the position of the absent labellum. 



Cases of this kind are the more interesting from 

 their relation to the fertilization of these flowers by 

 insects ; it seems as though, when the labellum, which 

 performs so important an office in attracting and guid- 

 ing insects, is deficient, its place is supplied by other 

 means. 



Displacement of the parts of the flower from elon- 

 gation of the receptacle is a not infrequent teratological 

 occurrence, resulting sometimes in the conversion of 

 the verticillate into the spiral arrangement. Instances 

 of this are cited under Elongation, ProHfication, &c. 

 In this place it is merely necessaiy to refer to a curious 

 circumstance that is met with in some double flowers, 

 owing to this separation of some parts of the flower 

 and the cohesion or adhesion of others. Thus, in 

 some double flowers of Primula sinensis and in the 

 Pea {Pidum sativum), I have seen a gradual passage of 

 sepals to petals, so that the calyx and corolla formed 

 one continuous sheet, winding spirally around the 



