6 THE GENUS CROCUS. 



consists of a series of imbricated annuli surrounded by short teeth (Fig. 5. D. E.) 

 which seem to be homologous with the wiry rays of the reticulated species. The 

 annuli of the annulate Croci represent the most condensed form of the whorl of 

 growth: a mere coriaceous ring, in which the superimposed row of little points 

 represent the separate points of growth analogous to the leaves developed from the 

 summit of the conn. 



Figs. 4 and 5, represent some of the more general types of structure of the tunic. 



Fig. 5. 



Fig. 5. A, The main tunic of C. cancellutitx; B, basal tunic. C, main tunic of C. Danfordia; D and E. 

 basal tunics; F, O, H, the main tunic, basal tunic, and cap of C. lavigatus. 



All these diverse structures, both of the main tunics and of the basal tunics, 

 which vary as regards pattern, are distinctly related to one common purpose, viz: 

 the protection of the corm during its annual reproduction and expansion within the 

 tunics. 



The thin, membranous tunics rupture during the expansion of the corm; and 

 the superimposed layers of shaving-like shreds maintain the continuity of the covering. 

 The function of the reticulated structure is also obvious, allowing lateral expansion; 

 and the stranded tunic of Croats Flcischeri also permits of lateral expansion. But 

 this widening out laterally involves the drawing up of the tunic from the base of 

 the corm, and but for the presence of the separate basal tunic, the bottom of the 

 corm would be left bare. The claw-like rays of the usual pattern bend strongly 

 upwards and inwards, and clasp the base of the main tunic as it slips upwards. 

 The basal annuli of the annulate species, with rows of little teeth on their upper 

 margin, slip over each other, and cling by the teeth to each other, and to the 

 bottom of the main tunic. 



