252 Stockard : Nectar-glands of Vicia Faba 



same layer in other portions, except for the fact that they rarely 

 contain chlorophyl-granules and that their nuclei seem a little less 

 irregular in form, tending to be as a rule spherical. Lloyd was 

 probably correct in his supposition that the cells lacking chloro- 

 phyl in the foliar nectar-glands of Pteridium were functional in 

 the secretory process. The epidermal cells of the gland are more 

 columnar in form than those of the general epidermis, being some- 

 times more than twice as long as broad. The hairs mentioned 

 above are really the only highly specialized structures to be found % 

 in these glands. The basal cell of the conical hair (figure 2, be) 

 is often inferior in size to any other cell present, and its contents at 

 times appears very scanty. The tip, or conical cell, of this hair is 

 highly modified, having an enormously thickened wall which in 

 many cases stained diffusely with the methyl green of Auerbach's 

 stain. In size this cell is more than twice the length of any other 

 present, and somewhat broader at its base than the epidermal cells. 



The more numerous hairs which for convenience have been 

 termed nectar-hairs, are constructed as described above. The 

 basal cell in this case (figure 3, be) is likewise somewhat smaller 

 than the neighboring cells, but its walls are not so thick as the 

 upper epidermal wall ; otherwise it is not remarkable. The outer 

 walls of the remaining four cells of the hair are thin, and the wall 

 forming the distal dome of the hair is very much thinner than else- 

 where. The inner partition-walls which separate the four cells are 

 also thin, though usually appearing thicker than the outer ones. 

 As before stated, the contents of these cells is very much like that 

 of the other cells of the gland, except in cases of old glands, when 

 the general gland-cell material stains lightly with the plasma-stains, 

 while these hairs are filled with substances tending to take the 

 nuclear dies. The nuclei of hair-cells (figure 13) are similar to 

 those of other cells, being vacuolated and changing with age in 

 much the same manner. 



I consider that the gland proper consists of the club-shaped 

 hairs and the several layers of cells below these, whereas the con- 

 ical hairs are accessory, being found in no other part of the stipule. 



B. Development. — Since the general glandular tissue re- 

 sembles in structure that of other portions of the stipule, little of 

 especial note is expected in its development. The case, however, 



