XVI."] THE BEAN PLANT. 479 



e. The contents of the embryo-sac are best studied 

 in material which has been preserved, when quite 

 fresh, in absolute alcohol, and then transferred to 

 a mixture of alcohol and glycerine. The alcohol 

 is allowed to evaporate, and the sections are then 

 made, and mounted in glycerine. With a high 

 power the following structures may be made out 

 in the embryo- sac : 



act. At the micropylar end three cells forming collec- 

 tively the " egg-apparatus." The most deeply in- 

 serted of the three is the ovum itself, the other 

 two are the synergidae and undergo no further 

 development. 



ft ft. About the middle of the sac the large nucleus. After 

 fertilization this divides, repeatedly, to form the 

 nuclei of the endosperm-cells, which are soon absorbed 

 in this plant. 



yy. At the end opposite the micropyle the three "anti- 

 podal cells." 



f. The seeds. 



i. Soak some dried beans in water for twenty- four 

 hours; they will slightly swell up and be more readily 

 examined than when dry. 



a. Note the black patch (the hilum) on one end of 

 the bean, marking where the stalk (funiculus) which 

 fixed it in the pod was attached to it. 



b. Having wiped all moisture off the bean gently 

 press it while observing that part of the black 

 patch which is next its broader end : close to 

 the patch a minute drop of fluid will be observed 

 to be pressed out through a small opening, the 

 micropyle. 



c. Carefully peel off the outer coat (testa) of the seed : 



