STUDIES ON SOME EXTRANÜPTIAL NECTARIES. 11 



A vascular system'^^ is found in nectaries of the second type. 

 The fibro-vascular bundles coming from beneath spread out in the 

 ground parenchyma of the nectary, and are connected with the 

 subglandular tissue by means of the conducting parenchyma. The 

 constituent elements of the greater part of the fibro-vascular 

 bundles end bluntly in the assimilatory tissue of the nectary. 



The nectar, secreted under favourable conditions for twelve 

 hours, amounts to such a quantity, as almost to equal the volume 

 of the nectary itself It is obvious that the secreting layer must 

 have derived from the inner tissues the water necessary to form 

 the entire mass of the nectar. It seems, however, that the vas- 

 cular system does not supply water directly to the secreting epith- 

 elium ; for I severed the midrib of the leaves of Prunus Lauro- 

 cerasus at a point, near the nectary, so as to cut off the nectary 

 from direct connection with the main vascular system, and repeatedly 

 washed off the nectar from the nectarine surface, but the operation 

 did by no means affect the quantity of the secretion. 



With Viburnum japonicum, I obtained the same results. 

 e. Crystals. 



Cells containing crystals of calcium salts (i. e. mostly oxalate, 

 sometimes carbonate) were present in large numbers in the nect- 

 aries of most of the plants which I studied. These cells are 

 larger than the ground parenchymatous cells and are distributed 

 along the water-passage. 

 /. Anthocyan. 



The extranuptial nectaries of Impatiens balsamina and Prunus 

 cerasus have a beautiful red colour owing to the presence of antho- 

 cyan in their secretory cells. The nectary of Sapium sebiferum has 

 a bright red colour only in the younger stages ; but in the case 



2) Ewart. I. c 



