I/O 



THE TEACHING BOTANIST 



grain as ovary united to seed ; and they may be led to notice 

 that the micropyle is not present, and that the scar of attach- 

 ment, while functionally a hilum, is not strictly so morpho- 

 logically. The occurrence of food substance outside of the 

 embryo in Morning-glory and Corn should be used to make 

 them seek for it in Beans and Horse-chestnut, and thus to 

 work out the differences between " albuminous >: and " ex- 

 albuminous" seeds. 



FIG. 15. Diagrammatic figures of embryos of Lima Bean, Morning-glory, 

 Horse-chestnut, and Corn, shaded to show morphologically equivalent parts. 

 Diagonal lines = hypocotyl ; vertical lines = cotyledons ; dots = plumule; 

 circles = food substance. 



Of the greatest morphological value is the Exercise 7 

 which is one of the best I have ever tried for inculcating a 

 true idea of morphology, the more especially when combined 

 with similar diagrams of germinated stages of the same seeds. 

 In making these diagrams all unessentials should be omitted, 

 and an effort made to represent only the principal correspond- 

 ing parts placed in corresponding positions. The diagrams 

 should be somewhat as illustrated in Fig. 15, except that the 

 equivalent parts can be brought out much better by colored 



