12 



On the Germinatiox of a Seed. 



By A. Martixelli. 



(Read October 2Uh, 1879.) 



Plate I. 



Some time ago I planted some beans (Phaseolus muWjiorus), 

 which bloomed but bore no fruit. On digging up their stems, I 

 found that the roots had thickened into tubers ; and having examined 

 their composition, together with that of an unplanted seed, I came 

 to the conclusion that the materials which should have formed the 

 fruit were stored up in the tubers, so that the plant might have 

 another start in the spring. I was led further to examine the com- 

 position of several cereals, to trace the relation of the embryo to its 

 perisperm, or source of nourishment — endeavouring to gain some 

 knowledge of the purpose which the various parts of the seed sub- 

 serve in the process of germination. The results of these enquiries 

 form the subject of the present paper. 



Seeds may be divided into two classes — Albuminous and Ex- 

 albuminous. In the former the term alhwnen is intended to include 

 all the various materials composing the wliite substance of the seed, 

 although the seed may contain but a very small proportion of the 

 substance technically so named. Tlie classification is based upon 

 position. In albuminous seeds the albumen or perisperm may be 

 described as exterior to, and separable from, the cotyledons or seed- 

 leaves ; in the buckwheat, for example, a transverse section, as at 

 Fig. 1, Plate I., shows its thin leafy cotyledons, in graceful folds, 

 intersecting the perisperm. During germination this nutriment is 

 absorbed through the succulent tissues of tjie embryo, and, finally, 

 the cotyledons, bursting the seed coats, are thrown upon their own 

 resources and at once prepare organised material for the growth of 

 the plumule (Fig. 2). In the Marvel of Peru (Fig. 3) the albu- 

 men forms the central mass of the seed, and so completely is it 

 enclosed by the cotyledons that it can only be recognised by a thin 

 white line on either side of the stem. But, in this instance, it may 



