42 



Membranes of Bud. 

 8. (a) Calyx-tube. 



(b) Inner operculum (No. 2). 



(c) Outer operculum (No. 1). 



(d) Fragments of an outer scurfy layer. 



(e) External membrane of the calyx-tube. 



(c) and (e) appear to correspond, so do also (a) and (b). (All of E. eximia Schauer.) 



The membranes covering the calyx-tube and operculum in E. eximia appear to consist of the outer 

 coverings of both organs. Each membrane is of such a tough, gelatinous-like nature that it can be. separated 

 without laceration. 



If (c), the outer operculum, is of calycine origin, then what about (e), which is obviously of similar 

 origin ] It seems to me that they both represent the calyx, and we have a key to the position in the 

 Hinged Operculum (see Part LV11I, p. 492), where, in numerous species of the Corymbosa?, it is shown 

 that in what corresponds to (c) and (e) there is a tearing, in other words, there is an indication of some 

 continuity between them. In the present case there is a sharp line of demarcation between (c) and (e), 

 but this must not be relied upon too much, as there is occasionally a fusion (and consequently a tearing) 

 of (c) and (e) in E. eximia also. 



Scurfiness. — The minute dark patches {d) on the outer membrane or outer operculum are due to a 

 scurfy substance which more or less envelops the young buds and is not uncommon in the Corymbosa?. It 

 is therefore present on the calyx as well as the operculum. 



We have a somewhat similar condition in E. terminalis, except that, in the latter sjaecies, the scurfiness 

 is more persistent, and also in E. cortjmbosa, where there is a note on " Scurfiness of .Fruits," at Part 

 XXXIX, p. 243. 



The Operculum (double, solid and hinged). 

 9a. (a) Outer operculum (of an amber colour when fresh) ; 

 (b) Inner operculum (of a green colour when fresh). 



E. maculata Hook. f. See also Part LVIII, p. 489. When the outer operculum is cast in 

 this species, the inner one is seen to be smooth and shining ; in this character it appears to 

 differ from all other species. 

 10. Showing the operculum, a little pyramidal cap, which has ceased to grow, and which is gradually 

 pushed off by the expanding stamens. E. letraptera Turcz.. cultivated in the Botanic Gardens, 

 Sydney. 

 11a. Side or oblique view of fleshy operculum. 

 11b. Longitudinal section of the same. Note the increasing thickness as the apex is approached, and also 



the cavity which serves to enclose the stigma and the upper part of the style. 

 lie. The same, looked at from above; the mould-like cavity for the stigma is seen as a small inner circle. 



E. mncrocarpa Hook., cultivated in the Botanic Gardens, Sydney, 13th August, 1917. 

 12a. External view of operculum. 

 12b. Oblique view of operculum. 



Note how fleshy it is. At the centre of the inside of the operculum (i.e., at the top of the 

 operculum) is a cavity which encloses the stigma and the top of the stvle. In the lithograph, 

 this cavity is not as clear as in the original. It is not as deep as in E. macrocarpa, as may be 

 readily inferred from the greater length of the umbo in this species. E. piriformis Turcz., Mullewa, 

 Western Australia (C. E. Chapman, October, 1919. It had shrunk a little when I received it). 



13a. The. winged, solid calyx-tube, which is orange-scarlet in colour. Note the slightly protruding stigma. 



13b. The almost solid operculum, square, with rounded corners at the base. Note the deeper shaded 

 circle in the centre, which indicates the sheath for the top of the style and of the stigma. E. 

 letraptera Turcz., cultivated in the Botanic Gardens, Sydney, 17th September, 1919. 



This method of protection of the stigma has been shown in three conspicuous instances. 

 It is, however, probable that in Eucalyptus the stigma is protected in a similar manner in all or 

 most cases, though it is obvious that in very small or thin opercula it would not be readily 

 seen. 



