SEED 215 



MATURE SEED AND EMBRYO. 



(A) Dicotyledons. 



I. (a) SOAK some Broad Beans for 24 hours in water : 

 selecting one which is fully swollen, note its flattened 

 form, and the dark blotch (the hilum) at one edge of 

 it : this is the base of the seed, by which it was attached 

 to the parent plant. Dry the surface of the seed and 

 squeeze it gently, water will be seen to exude from a 

 small hole close to the hilum : this hole is the micro- 

 pyle, and is a guide to the position of the technical 

 apex of the seed, the whole being of the curved or 

 campylotropous type. 



Remove the tough outer seed-coat, derived from the 

 integuments, and the bulky, yellowish embryo, which 

 occupies the whole space within the seed -coat, will then 

 be disclosed : it is to be observed that there is here no 

 tissue derived from nucellus, and no endosperm, and 

 the seed is therefore described as exalbuminous : note 

 the following parts of it : 



1. The two fleshy cotyledons, which are attached 

 to one another at one point, which is their base. 



2. The conical radicle, which lies externally, and in 

 the seed has its pointed apex directed towards the 

 micropyle. 



3. Separate the two cotyledons, and between them 

 observe a bud, the plumule, composed of numerous 

 small plumular leaves. 



(&) Compare with the Bean the flattened seed of the 

 Cucumber or Gourd : the micropyle may be found by 

 the same means as before, at the pointed end of the 



