SEEDS. 3 



whenever the description will be rendered more intelligible 

 by them. 



CASTOR OIL SEED. Ricinus communis, L. 



I. Study first the external features. 



1. Shape and surface. Compare different specimens as 



regards shades and distribution of color. 



2. Surface markings : 



a. The conspicuous, thickened protuberance at one 



end, the caruncle, a structure occurring in com- 

 paratively few species. 



b. The string-like raphe, extending from the hilum 



(faintly seen at the edge of the caruncle) to 

 the chalaza, near the other end. 



II. Remove the testa and observe the delicate inner 

 seed coat, endopleura, enclosing the kernel. 



III. Split the kernel longitudinally, so as to expose the 

 embryo. Examine under a dissecting microscope, or with 

 a good lens. Draw the inner surface of one of the halves 

 so as to show 



1. The outline and venation of the cotyledon. 



2. The short, straight radicle. 



3. The surrounding endosperm (tissue containing food 



material). 



IV. Record in detail what you have observed. Note 

 important differences between the castor oil seed and com- 

 mon bean. 



INDIAN CORN. Zea Mays, L. 1 



I. Study closely the external features of the grain. 

 How do the two sides differ ? 



1 The grain of corn is really a seed-like fruit, in which the coats of 

 fruit and seed are blended. Specimens for dissecting should be placed in 

 water the day before they are to be used. 



