8 STUDIi:S OF SEEDS AND SEEDLINGS 



Carefully remove for study the structures discovered within. Exam- 

 ine them with the lens. Describe all parts of the kernel with included 

 embryo. 



The substance surrounding the embryo is the albumen ; the leaves 

 are the cotyledons ; the axis, or stemlet upon which they are borne, is 

 the caulicle. 



Draw : (1) The embryo separated from the albumen ( x 2).i (2) A 

 longitudinal section of the kernel cutting the cotyledons in halves ( x 3). 



White Lupine. — The parts all become visible on removing the seed 

 coats and separating the well-marked halves of the seed. Xote caulicle, 

 cotyledons, and between the latter a third part, the plumule, of several 

 diminutive members. Compare with the embryo of Castor Bean, 

 noting striking differences. 



Draw the embryo with one cotyledon removed, so as to show the 

 plumule ( x3). 



Indian Corn. — Lying just beneath the surface of the grain is a 

 roughly wedge-shaped body. Remove this, leaving the pasty portion 

 — the albumen. In one face is a cleft. Pull this apart, exposing 

 structures within. 



Study the embryo now in hand. A longitudinal section will help. 

 In order to identify more surely the members of the embryo, study 

 also a sprouted seed, in which root and plumule show plainly. The 

 large single cotyledon is one feature to be especially noted. 



Compare and correlate all its different portions with the parts of 

 the embryos of Castor Bean and Lupine. 



Draw surface and sectional views of the embryo to show the 

 structure ( x 3). 



From the examples above answer the question. To what extent 

 is the new plant already formed within the seed before germination 

 begins ? 



Exercise II. The Provision of Food Designed for the 

 Earliest Growth of the Young Plant 



1. Where is the nourishment stored ? Answer this for Castor Bean, 

 Lupine, and Indian Corn. In addition, examine seeds of the Four- 

 o'clock, and others provided by the teacher. 



Longitudinal sections will generally show at once the location of the 

 food store, whether outside the embryo, in which case the seed is said to 

 be alhuminous, or within the much swollen tissues of the nascent plant 

 itself, when the seed is called exalbuminous, or lacking in albumen. 



Classify the seeds studied as albuminous or exalbuminous. 



1 This means the drawing is to be two times the size of nature. 



