Stockard : Nectar-glands of Vicia Faba 253 



The 



of the modified hairs is much more interesting. In very young 

 glands before their contents becomes colored, only the nectar-hair 

 type exists, a few of these being arranged in a central group. As 

 development proceeds new hairs are formed around these as a 

 center until the gland has attained its mature size and color. The 

 nectar-hair is formed in the following manner : the outer wall of 

 an epidermal cell protrudes above the surface to a height about 

 equal to its former depth (figure 4), and its nucleus, which up to 

 this time is still in the resting condition, now divides mitotically 

 (figure 5) into two and thus forms the first cell of the hair, 

 parent and daughter cell again divide horizontally and so give the 

 hair three cells arranged in a vertical row (figure 6). A vertical 



division of .the two upper, or distal, cells then forms the four-celled 

 arrangement of the mature hair (figure 3). This latter process 

 was not actually observed in my material, but is easily inferred 

 from the stages which do exist. 



The conical hairs (figure 2) are found only in glands that have 

 assumed the mature color, and are always far less abundant than 

 the above type. They also arise from an epidermal cell, and in 

 this case the epidermal wall retains its thickness while pushing up 

 to form the heavy cone of the hair. With the development of this 

 type of hair the gland has reached its mature condition. 



NUCLEAR AND CYTOPLASMIC CHANGES DURING SECRETION 



All observations recorded in these notes were made with Leitz 

 1/16 oil-immersion objective and number three ocular with the 



tube-length 170 mm. 



{a) The youngest glands taken from the terminal buds present 

 the following appearances (figures 7 and 14), The true nu- 

 cleoli, or plasmosomes, take the acid stains, thus giving with Auer- 

 bach's or Congo red a delicate pink color, and they are usually 

 surrounded by large vacuoles. Often two or more plasmosomes 

 are found in the same nucleus (figure 7). They differ slightly 

 in size in the various cells, as do also the vacuoles about them. In 

 some cases the vacuole disappears almost entirely, this being often 

 true of the nuclei in the young nectar-hair cells (figure 13, A). 

 The chromatin is granular in structure rarely giving the appearance 

 of a thread-like arrangement These granules in some nuclei are 



