260 Stockard : Nectar-glands of Vicia Faba 



part in the manufacture of the secretion-substance , but plays a more 

 or less passive role in the essential process of secretion. Further, the 

 cytoplasm also undergoes marked changes during the stages of 

 glandular secretion. It first becomes more vacuolated, and later 

 becomes more coarsely granular, and finally in the nectar-hairs 

 densely granular, at the same time changing its staining reaction 

 from erythrophil to cyanophil. Finally, one must admit that these 

 later changes of the cytoplasm, at least, are largely controlled or influ- 



d p 



SUMMARY 



1. The nectar-glands on the stipules of Vicia Faba contain 

 rows, or layers, of cells whose contents have different chemical 

 reactions, as is shown in life by their different colors. 



2. This difference in chemical reaction indicates very probably 

 a difference in metabolic activity of the cells, since those of defi- 

 nite rows have a similar reaction. The color-response of these 

 cells to acids and bases is the typical litmus change ; acids causing 

 the cell-contents to become red, bases changing it to blue. 



3. The cells of young glands differ but slightly from the 

 general tissue-cells. 



4. The nuclei are granular in structure, often coarsely vacu- 

 olated, with one or more plasmosomes surrounded by vacuoles. 

 Their shape tends toward spherical, but in old glands they become 

 shrunken and slightly irregular in form. 



5. The position of the nucleus in the secreting cells varies 

 greatly, but is more often near the center of the cell. 



6. The nucleus is never observed to give out granular material 

 to the cytoplasm, though evidence is strongly in favor of the sup- 

 position that it does transmit substance to the cytoplasm which 

 finally forms, or causes to form, granules and these take during 

 later stages the nuclear stains. 



7. In rare cases the nucleus loses its chromatin in older glands 

 and takes the plasma-stains, staining with the acid fuchsin of 

 AuerbaclVs. 



8. The cytoplasm undergoes changes in structure as secretion 

 progresses, at first becoming vacuolar, then slightly granular, still 

 taking the plasma-stains, and then finally becoming densely granu- 

 lar and staining with the nuclear dies. 



