ON FRUIT. 



Caroline. Then the peas, which I thought had been at- 

 tached to the midrib of the leaf, must grow from its mar- 

 gin : that seems very singular. Is there any instance of 

 leaves, in their common state, bearing seeds thus? 



Mrs. B. Yes ; a leaf has been discovered (the Bryo- 

 phyllwn) which has this extraordinary property : it bears 

 germs, susceptible of becoming young plants, and these 

 are situated on its margin, like the seeds in a carpel. 

 The same structure is found in the Malaxis paludosa, a 

 little plant, growing occasionally in bogs in this country. 

 Caroline. Well, it is not very difficult to comprehend 

 that a leaf may be converted into a pod, which you bot- 

 anists dignify with the name of fruit; but I cannot con- 

 ceive how you can metamorphose a leaf into what we ig- 

 norant people call fruits ; such as an apple, a cherry, or 

 a plum. 



Mrs. B. With a little farther explanation, I hope I 

 shall be able to accomplish this. Do you recollect the 

 structure of a leaf? 



Emily. It has a smooth upper surface, and an under 

 surface more porous, of a rougher texture, and generally 

 downy or hairy. Between these surfaces lies the pabulum, 

 a softer body, consisting of an expansion of the cellular 

 system, and this is traversed and intersected by the fibrous 

 vessels which form the ribs of the leaf. 



Mrs. B. Extremely well. In the pea-pod these sev- 

 eral parts are distinguishable. The leaf is doubled upon 

 its upper surface, so as to render the under surface exter- 

 nal. 



Emily. The most porous surface must, of course, form 

 the out side of the pod, otherwise the stomas could be of 

 no use. 



Mrs. B. This is the case not only with the pea but 

 with all carpels. The external surface takes the name of 

 epicarp : the upper surface of the leaf forms this thin 

 delicate skin, which lines the interior of the pod : it is 

 called endocarp; and the pabulum of the leaf is this soft 

 intermediate layer, which is denominated mesocarp. 



1230. What is said of the Bryophylum, and what other plant is there 

 of a similar character! 1231. What is Caroline unable to compre- 

 hend in relation to this subject'? 1232. How does Emily here describe 

 the leaf? 1233. How is this description applicable to the pea-pod? 

 1234. What is called the epicarp the endocarp and the mesocarp? 



