8 Introduction to Botany. 



7. After the drawings have been pronounced satisfactory 

 by the instructor, impart different tints to the separate 

 structures by means of colored pencils, using the same 

 colors for the corresponding parts in the germinated and 

 ungerminated seeds. Thus : color the cotyledons yellow, 

 the plumule and whatever develops from it green, the cau- 

 licle orange, the radicle and succeeding roots red, reserve 

 food outside of the embryo blue, and when the cotyledons 

 contain reserve food dot their yellow color with blue. 



8. In the germinating Lima bean, what structures grow 

 most rapidly at first ? Can you see any physiological 

 reason why one structure should develop before another ? 

 How does the seedling manage to rise through the soil 

 into the light and air ? 



9. Make a cross section of the main root where a whorl 

 of rootlets arises, and show by a drawing the method of 

 origin of the rootlets. What advantage do you see in the 

 disposition of the rootlets in a regular order around the 

 main root ? 



10. Follow the behavior of the cotyledons, and try in 

 this way to determine their functions. In your judgment, 

 at what stage does the process of germination cease ? 



11. After two or more sets of leaves have developed, 

 make drawings to show their position on the stem with 

 reference to the next higher or lower set. What signifi- 

 cance do you see in a regular arrangement of the leaves ? 



12. Examine the terminal bud of the seedling with a 

 lens and determine what structures develop from it. 



Castor Bean. 



13. Make drawings of the external appearance of a 

 castor bean from the two most important points of view. 

 Scale, x 2. 



