22 STKUCTriiE AND PIIYSIOLOCiY OF SEED TLANTS 



EXPERIMENT VI 



Does the amount of material in the seed have anything to do with the rate 

 of growth of the seedling ? Germinate ten or more clover seeds, and about 

 the same number of peas, on moist blotting paper under a bell jar. After 

 they are well sprouted transfer both kinds of seeds to tine cotton netting, 

 stretched across wide-mouthed jars nearly full of water. Only the roots of 

 the seedlings should touch the water. Allow the plants to grow until the 

 peas are from four to six inches high. 



10. Examination of the four-o'clock seed.i Examine the external surface 

 of a seed of the four-o'clock,^ and note the hardness of the outer coat. From 

 seeds which have been soaked in water at least twenty-four hours peel off 

 the coatings and sketch the kernel. Make a cross section of one of the 

 entire soaked seeds and sketch the section as seen with the magnifying 

 glass, to show the parts, especially the two cotyledons, lying in close contact 

 and encircling the white, starchy-looking endosperm. With a mounted needle 

 pick out the little almost spherical mass of endosperm from inside the coty- 

 ledons of a seed which has been deprived of its coats, and sketch the embryo, 

 noting how it is curved so as to inclose the endosperm almost completely. 



11. Examination of the kernel of Indian corn.* * Soak some grains 

 of large yellow field corn for about two days. 



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

 where the germ lies. Observe how this groove has become 

 partially filled up in the soaked kernels. 



B. 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 

 inner coat of ordinary seeds, since the kernel of corn, like 

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

 sents not merely the seed but also the seed vessel in which 

 it was formed and grew, and is therefore a fruit. 



C. Cut sections of the soaked kernels, some transverse, some 

 lengthwise and parallel to the fiat surfaces, some lengthwise 

 and at right angles to the flat surfaces. Try the effect of 

 staining some of these sections with iodine solution. Make 

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



1 Strictly speaking a fruit. 



2 Morning-glory seeds or grains of buckwheat also answer well. 



