58 ON LEAVES. 



The first appearance of leaves which the young plant 

 puts forth on the germination of the seed is formed by the 

 lobes of the seed itself, which we have already noticed 

 under the name of cotyledons. 



Emily. I have often observed them in lupins, when 

 they first shoot above ground, and wondered that the tiny 

 plant should be able to supply food to such thick sub- 

 stantial leaves. 



Mrs. B. It is, on the contrary, these leaves which 

 yield their substance to the tiny plant ; and as soon as 

 they have completed this function, and the whole of their 

 pulpy nutriment is consumed, they wither and fall off. 



But all cotyledons are not of a succulent nature : some 

 are thin, like other leaves, and are more commonly called 

 seminal or seed leaves. 



Emily. How, then, can they feed the young plant ? 



Mrs. B. By immediately elaborating the sap, which 

 the nascent root draws up from the soil. Seminal leaves 

 are furnished with stomas for this purpose, while fleshy 

 cotyledons have none ; in the latter, the conversion of 

 the cotyledons into leaves is but very imperfect : they 

 frequently remain under ground, and do not assume ei- 

 ther the form or color of a leaf. 



Emily. The cotyledons of peas and beans are of this 

 description ; in those of lupines the conversion is more 

 complete, though they remain succulent. 



Caroline. Since the fleshy cotyledons have no stomas, 

 I know not what they have to do in the open air : merely 

 acting the part of a magazine of food, they are more at 

 hand to supply the young plant with it under ground than 

 above it. 



Emily. But is it not wonderful that a young plant 

 should be able to absorb sap, and elaborate it from the 

 first moment of its existence ? 



Mrs. B. Not more so than a young chicken should pick 

 up grains of corn as soon as it has thrown off its egg-shell. 



302. What is the first appearance of leaves'! 303. When do the 

 leaves formed from the lobes of the seed, as in lupins, wither and fall 

 off? 304. What question does Emily ask respecting seminal or seed 

 leaves'? 305. How does Mrs. B. answer her! 306. What does 

 Emily say of the cotyledons of peas, beans, and Itipinsl 307. What 

 does Caroline say on the same subject! 308. What question does 

 Emily ask concerning the young plant 1 ? 



