250 Stockard : Nectar-glands of Vicia Faba 



is a limpid watery nectar found usually in the early morning as a 

 droplet on the surface of the gland. This seems to accord with 

 Wilson's observation that these glands may be made to secrete 

 by the stimulus of illumination. 



When the gland is examined microscopically it is seen to be 

 perfectly flat, lacking any infolding, and composed of several kinds 



of cells (figure i). The inner or lower cells and the epidermal 



layer seem slightly if at all modified in form, while the epidermal 

 ones are rather more columnar in shape than are those of the 

 general tissue-epidermis. Two kinds of hairs are found on the 

 surface of the glands; one a long slender conical body composed 

 of two cells (figure 2), a small slightly modified basal cell and a 

 long conical apical cell which forms the main body of the hair. 

 This hair is pale-greenish or colorless during life and has a very 

 thick wall. Its function is probably sensitive, though this could 

 not be definitely determined. Haberlandt has suggested that these 

 hairs in another species serve to hold the secretion and prevent its 

 falling off, but I fail to understand, on account of their scarcity on 

 the gland-surface, how they could perform such a function. The 

 other hairs (figure 3) are entirely different in shape, being some- 

 what club-like, and consisting when mature of five cells. These 

 cells are definitely arranged with a single basal cell usually somewhat 

 smaller than the rest, and four larger cells placed in two pairs one 

 immediately above the other. The four cells might be described 

 as forming the four quarters of an ovate spheroid. These cells 

 contain the secretion-products just as those in other parts of the 

 gland and their color and appearance in life are due to this sub- 

 stance. These will be termed nectar-hairs for the sake of con- 

 venience. De Bary states that the glandular properties of these 

 cells have not been observed, but their close similarity to cells of 

 other parts of the glandular area makes it obvious that in younger 

 glands at least these hairs do serve the ordinary secretory functions. 

 The fact that they arise directly from the epidermal gland-cells 

 further suggests their glandular properties. 



The color and color-changes in the gland-cells are most inter- 

 esting. When examining free-hand sections of the living material 

 one finds a brilliant red and a deep blue color arranged in various 

 patterns. At times the epidermal layer with the nectar-hair cells 



