136 FIELD, FOREST AND FARM 



heart-shaped; in the carrot, long and narrow like 

 little tongues. These two leaves that precede the 

 others are known as seminal leaves. They come 

 from the two cotyledons, which generally open in the 

 air and grow green while nourishing the young plant 

 with a part of their substance ; but sometimes, as in 

 the acorn, they remain hidden underground. On the 

 other hand, seeds having but one cotyledon come up 

 with only one seminal leaf, generally narrow and 

 long. This is what we observe if we watch the ger- 

 mination of a grain of wheat. 



"A simpler and quicker method may be used for 

 ascertaining how many cotyledons a seed has. Hold 

 a leaf up to the light and you will see its texture 

 traversed by a multitude of little cords which serve 

 it as a kind of framework. These cords are called 

 veins or nerves. Now then, if you compare the leaf 

 of a pear-tree with a blade of wheat, or reed, you 

 will see that in the former the veins are more and 

 more subdivided and ramified, joining one another 

 and thus forming a network with irregular meshes, 

 while in the latter the veins do not branch, but run 

 in parallel lines without forming meshes. We 

 should find the same difference of framework be- 

 tween the leaves of the elm, poplar, and plane-tree, 

 on the one hand, and those of the iris, narcissus, and 

 tulip, on the other. This difference being estab- 

 lished, I will add that with few exceptions, of no 

 interest to us here, every plant with netted-veined 

 leaves has two cotyledons in its seed, and that every 

 plant with parallel-veined leaves has but one. Con- 



