MORPHOLOGY OF THE SEED 169 



will seem to them as one. They should see that the hypocotyl 

 does not lie against the cotyledons as in the Bean, but is sepa- 



* 



rated from them in part by a seeming pocket of the coats 

 (really due to a folding of the young ovule enclosing part of 

 the coats) ; and that the seeming hypocotyl really splits down 

 part of its length and has the plumule at the bottom of the 

 split. In the Morning-glory they should find (with help of a 

 lens) micropyle and raphe as well as hilum, and the jelly-like 

 endosperm and the two cotyledons. In the Com they should 

 see, in addition to the other parts, the remnant of the silk 

 (style) and the leaves of the plumule, on a failure to see which 

 they should be reminded, not simply to look at things, but 

 also to move and separate them. 



Of the utmost importance in biology is morphology. Prac- 

 tically, it consists chiefly in recognizing the original nature of 

 parts, no matter how much disguised by changes of size and 

 shape. Its best index is the relative positions of parts. The 

 Horse-chestnut is good to begin with, for the student may be 

 made to work out for himself, by careful comparison with the 

 construction of the embryo in the Bean, that what he at first 

 always takes for " hypocotyl hollowed out with the plumule at 

 the bottom," is really largely stalks of the cotyledons, while 

 the hypocotyl is only the part below the plumule. In the 

 Morning-glory he is apt at first to mistake the very leafy cotyle- 

 dons for plumule, but can be led to work out their true nature. 

 And in the Corn he can thus discover that the shield-like 

 body is cotyledon. (Actually there is some slight doubt on 

 this point among experts, but it is probably true, and can be 

 so treated, with a caution to the students.) The observation 

 of the remnant of the style on the corn grain, and their ina- 

 bility to find any equivalent for it on the other seeds, may be 

 used to introduce an explanation of the composition of this 



