10 ART. 3. K. ONO. 



than in any other part of the plant. The cnticle^^ no doubt 

 allows, in certain instances, of the secretion of the nectar through 

 its substance. 



h. Secretory layer. 



The cells of the secretory layer are generally of an elongat- 

 ed prismatic form, and are compactly set together. They are 

 rich in granular protoplasm and numerous vacuoles. Chlorophyll 

 grains are lacking in the fully developed nectaries, except in the 

 case of Cassia sulfurea and C. occidentalis. Sugar is commonly 

 found in the cells of the secretory layer, while fat and tannin 

 are rarely present. Nuclei with nucleoli are fairly distinct, 

 especially in the younger stages, and are always found near the 

 centre of the cells. 



After the secretion of the nectar, the secretory cells shrink, 

 but after a few days often recover their original condition. 



c. Subglandular layer. 



This layer is found under the secretory layer of the nectaries 

 of the second type only, and its physiological significance is the 

 same as that of the basal cells of the nectaries of the first type ; 

 it also resembles them in its morphological characters. The 

 subglandular layer has no intercellular space, and the cells 

 themselves are generally smaller than the neighbouring parenchy- 

 matous cells. The nucleus is comparatively large and the chlo- 

 rophyll grains are often found in the cell, as is the case with 

 Prunus yedoensis, Idesia polycarpa, Viburnum japonicum, etc. 



The function of this layer is evidently to cause the osmotic 

 pressure from inside, necessary to the secretion of the nectar. 



d. Vascular system. 



1) Kroemer. Wurzelhaut, Hypodermis u. Endodermis der Angiospermen-Wurzel. 

 Bibliotheca Eotanica. Ed. XII, Heft 59. 1903. 



