254 Stockard : Nectar-glands of Vicia Faba 



figures 



closely packed, causing them to stain very heavily, while other 

 nuclei in nearby cells contain much less chromatic substance (fig- 

 ure 12). The nuclei of the gland-cells are somewhat larger and 

 more spherical than those found in the adjacent tissues. 



The cytoplasm appears finely granular in structure and is often 

 more or less vacuolated. The cytoplasm in the hair-cells does not 

 differ noticeably from that in other cells of the gland. It is usually 

 densest about the nuclei and never contains any nuclear staining, 



or cyanophil, material. 



(b) Considering now a gland that is slightly older or more 

 mature than the former, being the next lower on the stem of the 

 terminal bud. Here are also found 

 of various size about the plasmosomes. The chromatin is again 

 granular as a rule, but many nuclei preparing for division are in 

 spireme stage. In some again the granules are densely arranged 

 while in others the chromatic substance is less abundant. 



The cytoplasm is granular in appearance, with numerous vacu- 

 oles, and is densest about the nuclei. In a few of the central and 

 therefore oldest nectar-hairs the granules of the cytoplasm have 

 become cyanophil and stain heavily. The walls of these hairs have 

 slightly shriveled. All of the nuclei in the nectar-hairs and the 

 epidermal cells are situated near the cell-center, while in lower 

 layers the nuclear position is not so constant. 



(c) The cells of the next older gland on the stem are still col- 

 orless. The nuclei have large vacuoles about the plasmosomes 

 (figures 8, 9, and 1 1). The chromatin is granular but more dif- 

 fuse or not so densely arranged as in the two younger, some nuclei 

 being thin and pale. The nuclei of the nectar-hairs are much 

 poorer in chromatin than those in similar parts of the glands above 

 (figure 13, B). The plasmosomes are about equal in size in these 

 three stages of the glands. 



The cytoplasm is coarsely granular, being again dense around 

 the nuclei, and contains a few basic staining or cyanophil granules. 

 There is no chlorophyl in any of the cells of these three glands, 

 which appear white in life. 



(d) The youngest gland containing colored material. The 

 nuclei are vacuolated about the plasmosomes (figure 16), but as 

 a rule those of the nectar-hairs do not contain as large vacuoles 



