1 86 Oranges and Lemons of India. 



122, fig. k, shows rind-oil cells, which are larger than 

 many pulp-vesicles. Fig. e y pi. 76, shows a section of 

 the juice cells in a pulp carpel. It gives approximately 

 the same disposition of large and small cells, as that 

 seen in the leaf and rind. 



If, however, further proof be required of the relation- 

 ship between the pulp-vesicles and the rind oil cells, it 

 can be obtained from a genus which is closely allied to 

 the citrus. In fig. c, pi. 242, is given a longitudinal 

 section of the pulp carpel of the CEgle marmelos (the 

 bcel fruit). The interior surface of its wall is studded 

 with open mouthed cells, which pour out a transparent 

 mucilaginous substance, with which the interior of the 

 carpel is filled. This is the gummy matter of the boel fruit, 

 and is soluble in water. These opened mouthed cells of 

 the pulp carpel of the "bcel " fruit, I take it, can be no 

 other than the homologues of the citrus juice cells on the 

 one hand, and of the rind cells on the other. In the citrus 

 they are closed sacks, and develop, not on\y#tuafage,but 

 also acid and sugar; all these three substances, it would 

 appear, might be easily changed from one to the other.* 



The view I have taken of the morphology of the 

 pulp vesicles of the citrus is, I think, further supported 

 by fig. h, pi. 49. It shows some undeveloped juice 

 vesicles. They are mere projections, tipped with a 

 hair-like point, not unlike the gum-cells of the CEgle 

 marmelos, although in this citrus instead of being open- 

 mouthed, they are closed cells. Moreover in fig. b, pi. 

 66, we have the large balloon-shaped cells of the rind, 

 pedicelled, like many of the juice cells. Although the 

 pulp vesicles are often squeezed into all manner of 

 shapes, I think it will nevertheless be seen that they 

 are roughly divisible into three grades, like the oil cells 

 of the rind and leaves. This, however, is not of much 

 * See Appendix, No. 59. 



