20 ELEMENTS OF BOTANY. 



Sketch an unsoaked kernel, so as to show the grooved side, where the 

 germ lies. Observe how this groove has become partially filled up iii the 

 soaked kernels. 



Remove the thin tough skin from one of the latter, and notice its 

 transparency. This skin — the bran of unsifted corn meal — does not 

 exactly correspond to the testa and tegmen of ordinary seeds, since the 

 kernel of corn, like all other grains (and like the seed of the four-o'clock), 

 represents not merely the seed, but also the seed-vessel in which it was 

 formed and grew as well as the outermost part of the flower (the 

 calyx). 



Cut sections of the soaked kernels, some transverse, some lengthwise 

 and parallel to the flat surfaces, some lengthwise and at right angles to 

 the flat surfaces. 



Make a sketch of one section of each of the three kinds, and label the 

 dirty white portion, of cheesy consistency, embryo ; and the yellow 

 portions, and those which are white and floury, endosperm. 



Chip off the endosperm from one kernel so as to remove the embryo 

 free from other parts.^ Notice its form, "somewhat triangular in outline, 

 sometimes nearly the shape of a beechnut, in other specimens nearly like 

 an almond. 



Estimate what proportion of the entire bulk of the soaked kernel is 

 embryo. 



Split the embryo lengthwise so as to show the slender, somewhat 

 conical plumule.^ 



Sprout a considerable number of kernels of corn in sand or pine saw- 

 dust, at a temperature of 70 or 80 degrees, and make several sketches to 

 illustrate the growth of the plumule and the formation of roots ; first 

 a main root from the base of the caulicle, then others more slender 

 from the same region, and later on still others from points higher up on the 

 stem. The student may be able to make out what becomes of the large 

 outer part of the embryo. This is really the single cotyledon of the corn. 

 It does not rise above ground, but most of it remains in the buried grain, 

 and acts as a digesting and absorbing organ through which the endosperm 

 is transferred into the growing plant, as fast as it can be made liquid for 

 that purpose. 



1 The emtryo may tie removed -with great ease from kernels of rather mature 

 green corn after twenty minutes' boiling on the cob, then picking the kernels ofE 

 one by one with the point of a knife. They may be preserved indefinitely In 

 alcohol. 



2 The teacher may well consult Figs. 66, 67, 68 in Gray's Lessons in JBgta,ny^ 

 revised ed. 



