Morphology of the Citrus. 193 



sets on its surface. Its juice is "fade ou mdetermine*." 

 Finally, the kuthairee nimboo has its cells, which are 

 the only ones visible on its lumpy projections, convex, 

 while its juice is distinctly sour, and nothing else. 

 In plate 83, fig. a, are shown convex oil-cells (B), and 

 concave oil-cells (A), on the same fruit. 



It would therefore appear that Risso's notion about 

 the constant relationship of the concave or convex 

 cells of the rind, to the acid or sweet juice of the pulp, 

 is untenable. 



That there is a relationship between the oil-cells of 

 the rind and the juice cells of the pulp, I fully believe, 

 but it would appear only one of descent, from a common 

 stock the oil cells of the leaves ; or to put it perhaps 

 more accurately, according to my view the oil-cells of 

 the bark, of the leaves, and of the rind, and also the 

 juice vesicles of the pulp have a common origin, and 

 are homologous. 



Closely connected with its morphology is the des- 

 cent of the citrus. By this I mean the various phases 

 it has passed through, and the means by which it has 

 been able to struggle into the' prominent place it now 

 occupies. Of course I can only make an attempt to 

 penetrate its past transformations by means of the 

 lights before me, and a great deal of what I am about 

 to say must be speculative. Nevertheless, from what 

 is before us, we can to some extent argue back to what 

 has past, perhaps for ever, and obtain a glimpse of it, 

 somewhat in the way that the Palaeontologist attempts 

 to clothe a few ancient bones with the forms they 

 might have had, by piecing together notions he has 

 obtained from animals now existing. In order to 

 make my thoughts clear some repetition may perhaps 

 be pardoned. 



I think we have first to divest ourselves of the idea 



o 



