124 BIOLOGY 



egg. The relation of these different bodies to one another and 

 to the general process of reproduction will be considered in a 

 later chapter. 



LABORATORY WORK ON THE CASTOR BEAN 



Seeds may be obtained at almost any seed store. For the study of the 

 seeds they should be soaked over night in water, which will soften them so 

 that the outer covering may be removed and the seed readily dissected. 



The study of the plant structure should be made from young seedlings. 

 Soak the beans in water over night and then plant them in a box containing 

 moist sawdust, covering the box with a piece of glass to prevent evapora- 

 tion. Place the box in a warm place and water the seeds daily, keeping 

 the sawdust quite moist. The seeds will sprout quickly and at varying 

 periods of growth plants may be removed, the sawdust washed from their 

 roots, and the plants studied as a whole. 



For the study of the stem both cross sections and longitudinal sections 

 should be made with a sharp razor, the piece of the stem to be sectioned 

 being held between two bits of pith which are hollowed out to receive them. 

 These sections may be mounted in water and studied directly, without 

 any further preparation. Some points can be seen more satisfactorily by 

 the use of various stains. It is best to begin with the study of a young 

 seedling about two inches high, and to follow with older plants which will 

 show the growth of the fibrovascular bundles and their fusion into a ring. 

 All of the points mentioned in the text should be studied. 



The study of the root is made in the same way. To obtain root hairs, 

 it is better to sprout sunflower seeds by placing them, after soaking in 

 water, between two layers of blotting paper in a covered dish, which should 

 be kept moist and warm. After two or three days the rootlet of the young 

 seedling will show a mass of root hairs. They should be examined through 

 a lens without disturbing the seedling, and then one of the rootlets should 

 be placed in a watch glass in water and examined with a microscope. 



The epidermis of the leaf may be studied by stripping off with fine forceps 

 a bit of the epidermis from the upper or under side of a leaf. Any plant 

 will serve for this, and it is well to examine the epidermis of several different 

 plants. The study should be made with a high power. The internal 

 structure of a leaf must be made by cross sections. These are very diffi- 

 cult to make, and prepared, stained sections should be furnished by the 

 instructor. 



The stems of other plants showing annual rings of growth should alsc 

 be studied in both cross and longitudinal sections. Twigs of the pine, 



