ANGIOSPERMS. 
605 
Deviations from this type are produced by the formation of two or more stamens in 
place of each of the upper (inner) ones; in the Gruciferae usually two (Fig. 413), in the 
Gleomeae sometimes two, sometimes more (Fig. 412 B). Such a replacement of one 
stamen by two or more is termed by Payer Dedoublement^, by Eichler and others Colla- 
teral Chorisis, and must apparently be considered as a branching of very early origin. 
This view is confirmed in this case by the fact that in the Grucifer Atelanthera the 
Fig. 412 — Diagram of the flower of Capparideae ; A Cleome dro- Fig. 413.— Diagram of tlie flower of 
sercefolia, B Polanisia graveoleiis (after Eichler). Cruciferce. 
median stamens are only split and the two halves of each provided with half-anthers, 
while in Crambe each of the four inner stamens puts out a lateral sterile branch, which 
may be explained as the commencement of a further multiplication of the stamens 
such as actually occurs in the Grucifer Megacarpcea and in many Gleomeae. Even if 
the way in which increase of the typical dimerous number of the inner whorl of stamens 
has been brought about be still obscure, it appears certain that the inconstancy of 
the number of the members of the staminal whorl proves that in Gruciferae and Gle- 
omeae a deviation has arisen in this part of the flower from the typical dimerous number, 
while the other whorls have remained unchanged. The only deviation which occurs in 
the gynaeceum of the Grucifers is in the genera Jetrapoma and Holargidium, where, 
besides the two lateral carpels, two median ones are also produced, thus forming a 
four-lobed ovary ^. 
An essentially different kind of increase in the typical number of the members of a 
floral whorl may be caused by the formation in the still very 'young bud of new 
members of the same kind between those already in existence and on the same zone 
FIG. 414,— Diagram of the flower oi Dütamnus FraxineUn (cf. Fig. 38 ). 
of the receptacle ; i. e. by what we have already described as the Interposition of new 
members. This I found to occur, for example, in Dictamnus Fraxinella (Fig. 388), and 
is represented in the diagram, Fig. 414, by the stamens of later origin being shaded not so 
dark as those of eariier origin. It may, I think, be inferred from Payer's descriptions 
^ [The theory of an original dimerous symmetry in the flowers of Cruciferze has been pushed 
still further by Meschaeff (Bull. Soc. Imp. Nat. Mose), who regards the four petals as also the result 
of a lateral dedoublement of a single pair (see Bentham, Ann. Address Linn. Soc. 1873).] 
[Holargidium is a section of Draba. According to Bentham and Hooker the four carpels of 
Tetrapoma are an abnormality not constant under cultivation. The same authors also mention the 
occasional occurrence of a similar abnormality in Brassica and Nasturtijun.'} 
