CUTICLES or CYCADEAN EEONDS. 



169 



intervening between the guard-cells and the subsidiary cells. There seem to be typically 

 two series of these intercalated cells (PL 18. fig. 14), but the number of series as seen iu 



section through a stoma shows a little 



apparently owing to irregularity 



position of the cells ; this is seen in text-fig. 17. In M. cylindrica the outer air-space 



is 



Ion 



& 



and narrower towards the opening, owing to the slight overarching of 



subsidiary cells, which 

 fig. 14). The openin 



slightly raised above the level of the epidermis (PL 18 



ff as 



seen in surface view is 



al or ellipt 



m 



shap 



In 



M. Denisonii the outer air-space is shallower and wider (text-fig. 17). In all cases the 



space is fairly heavily lined with 



The subsidiary cells vary from five 



ht in number, but are typically six, as in M. Denisonii (text-fig. 15) and M. JIop 



(text-fig. 16). 



Fig. 15. 



Fig. 16. 



Fig. ,17. 



Macrozamia i>eHi.om7.-Lower cuticle in surface view (after maceration), showing stoma-opening 



surrounded by six subsidiary cells. X 450. 



3/- Hopei. 



cells 



The dorsal surfaces of the guard-cells are indicated at d, X 450. (This cuticle was not removed by 



., . 11 x.i__ j-t.:.v«^:«« r.f +I1A fii'r-Knftnfi and suard-cells shows through.) 



M.De 



msoniL 



■Lower cuticle, showing a section through a stoma. 



gul: 



cfuard 



X450. 



