BOTANICAL SUBJECTS. 355 



Theu, at p. 31, they say : " Xous venous <le voir des etamines 

 placees dans le plan <lu uectaire ;* la Fig. 19 nous en niontre 

 })lacees dans I'iuterieur meme de ce plan." 



This means that the stamens of the Citrus may be inserted 

 outside the disk, on it, or inside it. Xormally, however, they are 

 outside it. Nevertheless, this abnormal condition leaves the 

 impres.«iion that the disk of the Citrus is only a suppressed tvhorl 

 of stamens. Indeed, in cases where a stamen adheres to the peel, 

 as is shown in Fig. 158 (6), such a stamen replaces one of the 

 lobes of the disk. Kis.so and Poiteaii say : " Quand une etamine 

 adhere a I'ovaire, son point d'insertion est dans le plan meme du 

 nectaire, et elle y cause une interruption." I do not think that this 

 leaves us in much doubt about the adhering stamens being part 

 and parcel of the disk, and that the latter is normally only a 

 suppressed whorl of stamens. 



But what about the orange peel to which the .stamens .some- 

 times adhere ? ^ 



What 1 have already quoted from Risso and Poiteau shows that 

 the filament of the adherino; stamen bv degrees loses its white 

 colour, and takes on that of the orange peel, and becomes identified 

 with its structure, which means that the filament and the peel are 

 one thing. Indeed, in the London sho])s and on the street 

 >)arrows, among the heaps of oranges, one may frequently pick 

 out a specimen which has a longitudinal raised strip on the peel, 

 running from base to apex, and inflistinguishable from the j>eel. 

 Presumably, the genesis of this raised strip is the Jilament of a 

 .stamen emerging from the disk and adhering to the ovary, and 

 eventually becoming identified with the peel. 



Risso and Poiteau show all the disks on Tab. I., divided into 

 segments. The segments, which mark the peel of many varieties 

 of Citrus, appear to be no other than a repetition of the lobes of 

 the disk (as shown in Fig. 15H {d) ), which, in turn, are trans- 

 formable into stamens, therefore they and the peel proper may 

 be reasonably considered as homologous with the sheath of the 

 P(Eonia Moiitan, which I am s^itistied is the fasciation of the 

 filaments of aborted stamens. 



The accompanying Fig. 159 shows a lemon devoid of pulp, 

 with all its peel segments dissociated. The reader may call them 



By nectaire the disk is meant. 



z 2 



