'216 LETTER XLVIII. 



cells through which it would have to filter are soon 

 choked up, and then the altered food is forced to accu- 

 mulate in the parench^-nla (Jjg. 2. and 2, * b.). Being 

 thus arrested in its course, it swells the tissue in 

 which it lies, becomes more and more changed by 

 constant exposure to light and air, till at last the 

 succulent flesh of the Mango is the result. 



As to the parenchj-ma of the inside of the pericarp, 

 as it is cut off by the shell from all communication 

 with the flesh, and is continually pressed upon by the 

 seed as it grows, being thus jammed as it were be- 

 tween the shell and the seed, it is not unnatural that 

 it should become so hard and solid as we find it. 



The seed is attached to the bottom of the pericarp 

 by a broad space (extending from h to e in Jig- 3.), 

 and stands erect in the cavity. It has two distinct 

 skins, one of which (Jig. 3. b.) is thin, pale, mem- 

 branous and loose, the other and inner (Jig' S. c.) 

 thicker, darker coloured, and fitting close to the 

 embryo. 



The inner skin does not grow from the same part of 

 the pericarp as the outer, but springs from the top of 

 a cord which arises obliquely from one side of the 

 base (Jig. 3. d. and 4. c). From its junction with the 

 inner coat to a small depression upon the edge (Jig. 

 3. g.), the cord throws out veins which, taking a 

 curved direction, and following the form of the embryo, 

 fill the whole of the inner coat with a network of 

 vessels. 



The cord alluded to is the raphe, the depression 

 upon the edge of the seed the centre of the chalaza. 



