210 PRACTICAL BOTANY 



be thus laid bare, or the embryo must be removed from 

 the ovule. The former is the more accurate method, 

 though the latter is much the easier: the latter will 

 therefore be adopted. 



Press gently with a needle upon the cover-slip of 

 the above preparation, so as to burst the ovules : the 

 embryo will escape in some cases without injury ; but 

 this will only be the case when fresh material has been 

 used ; after hardening in alcohol the embryos will not 

 readily leave the ovule. Neutralize the potash with 

 dilute acetic acid. The structure of the embryos, 

 which now lie freely suspended in the fluid, may be 

 easily studied. 



Apply the same method for the preparation of 

 embryos, from ovaries of various ages, both younger 

 and older than that first taken. A series of prepar- 

 ations may thus be obtained illustrating various stages 

 of development of the embryo, such as are figured in 

 ordinary text-books. 



Note more especially the following successive stages 

 of development : 



1. The suspensor, consisting of one or more cells 

 and terminated by a single embryonic cell. 



2. The embryonic cell divided into octants arranged 

 in two tiers : the suspensor is elongated and the cells 

 divided so as to form a series, of which the basal cell 

 (that nearest the micropyle) is usually enlarged greatly, 

 so as to exceed the embryo in size, and beginners are 

 apt to mistake it for the embryo: the terminal cell 

 next the embryo (the hypophysis) encroaches between 

 the four lower octants of the embryo. 



3. The octants so divided as to form three layers 



