LIFE-HISTORY AND PHYSIOLOGY. 7 



In C. lavigatus, where the annuli of the basal tunic are absent, the protection 

 of the bottom of the corm is effected by an adaptation of the structure of the main 

 tunic, which is split up into a series of vandyke divisions; these strongly bend 

 inwards in a downward direction, and clasp the bottom of the corm. The successive 

 annual tunic-layers are very persistent; and in the wild state, as many as fifteen or 

 twenty super-imposed tunics may be counted, representing- as many years growth 

 and complete reproduction of the entire plant. 



Foliar Organs. Of the two distinct sets of leaves, the sheathing- leaves, envi- 

 roning the base of the plant, are much shorter and broader than the proper-leaves; 

 they vary from three to six in number, and closely invest the ascending axis. 

 The inner sheathing-leaves are invariably longer than the outer; and thus as regards 

 length graduate inwards towards the proper-leaves, into which they also graduate 

 in structure, the lowest and outermost being a mere membranous tube, the longest 

 and innermost generally foliaceous, spathulate at its extremity, and only tubular below. 



The sheathing-leaves generally fall short of, but occasionally exceed the proper 

 spathes; their relative lengths are sufficiently constant for use in specific determination. 



The sheathing-leaves, excepting only in one species, exceed the basal spathe. 

 In Crocus lazicus they are almost abortive, leaving the basal spathe exposed. 



The next organs, approached in an inward and upward direction, are the proper- 

 leaves, familiarly known as the Grass of the Crocus, in which there is a great 

 variety of structure and of size. The leaves of Crocus venues, a section of which, on 

 an enlarged scale, is represented in Fig. 6, A, are of the type most commonly 

 found in the genus; in which the blade is about an eighth of an inch (0.0032 

 Metre) wide, and the keel about one third the width of the blade. The blade is 

 always somewhat revolute, approaching the margins of the keel, and forming with 

 the sides of the keel the lateral channels at the back of the blade. The lateral 



Fig. 6. Leaf sections. A, vermis, B, sativus C, nvdiflorus. 



