STRUCTURE. 



73 



mucilage. Cylindrical and clavate mucilage hairs are common in N. alba 

 (Schilling, 1. c.), and appressed finger-like ones occur in N. rubra. They 

 are shed as soon as the tissues of the leaf begin to elongate rapidly and 

 become mature, being of use only to keep the developing organs em- 

 bedded in a coat of slime. This phenomenon was noted by Irmisch in 

 1859. Subsequent to the development of mucilage hairs, or along with 

 and among them, longer hairs are formed in most Nymphaeas. The 

 early stages of these are exactly as just described ; the apical cell, how- 

 ever, instead of remaining spherical, elongates and may undergo division 



(e) 



FIG. 33. Hairs and hair bases : (a) on petiole of N. oilnrata ; (ft) on petiole of N. rubra, the shaft being 

 shed; (c) on petiole of N. tetragnna, showing also the cullenchyma immediately below the epidermis; 

 (d), (e), from rhi/ome of N. tuberosa. 



into a number of cylindrical elements as in Eu-castalia. The terminal 

 cell is bluntly rounded in Eu-castalia or acute in Lotos. These longer 

 hairs are persistent all over in members of the Lotos group, but only at 

 the bases of the petioles in Eu-castalia, and as a specially developed ring 

 of long hairs at the summit of the petiole in N. amazonum. In Lotos the 

 shaft of the hair is unicellular. Its base may be very much wider than the 

 basal epidermal cells in the petiole of N. rubra and sturtevantii, or but little 

 wider, as on the under side of the leaves of N. rubra. The hairs of the 

 ring on N. amazonum consist of 12 to 15 cells, and reach a length of 0.48 

 cm. Stahl (1888) considered the mucilage and other hairs as intended for 

 protection against animals (snails, &c.), and Goebel (1893) suggested that 

 they served to prevent contact of the young organs with one another in 

 the bud ; but Schilling (1894) regards them rather as useful in preventing 



