A. MAUTINELLI OX THE GERMINATION OF A SEED. 13 



be disconnected from the embryo whole, and in such integrity that it 

 has every appearance of a miniature plaster cast, as shown at Fig. 

 4 — the deep depression in the centre being the channel in which the 

 stem laid buried. Experiments have been made in separating the 

 embryo from its perisperm and supplying it with artificial nutri- 

 ment. They appear, however, to have been attended with so little 

 success that none of the experimentalists have boasted of their 

 2yroteges. 



But in Exalbuminous seeds, the bean, for example (Fig. 5), the 

 albumen is not thus separable from the cotyledons. It has been 

 entirely absorbed within their tissues, so that, with the plumule, they 

 occupy the whole cavity of the seed. In germination the cotyledons 

 of the bean remain beneath the ground, as shown in Fig. 6, and do 

 not in any degree partake of the character of leaves. They act 

 solely as repositories of assimilated material to nourish the plant in 

 its earlier stages. In this respect, the lupine, another example of 

 the class, does not differ from the bean ; but its cotyledons have 

 the faculty of developing chlorophyll and rising to the light (see 

 Fig. 7). They partially perform the function of leaves. I am, 

 however, able to show the true significance of these organs ; but if 

 a society existed for the prevention of cruelty to plants, I certainly 

 would not risk the exhibition of the lupine, shown in Fig. 8. 

 This plant was deprived of its cotyledons one week after germina- 

 tion, and for the two following months it only just maintained its 

 status quo, adding neither to its weight nor bulk. At the end of 

 that time I gathered it within the folds of my herbarium. 



From the above instances it would appear that the cotyledons 

 may assume three distinct phases. In the buckwheat they become 

 the first leaves of the plant, providing for the plumule until the true 

 leaves are formed. In the lupine, by the growth of the lower axis 

 of the stem, the cotyledons rise to the light as organs of assimila- 

 tion. But the bean grows only from the upper axis of the stem, 

 and hence the cotyledons remain in the ground. 



Now if one of the cotyledons of the bean is broken up, the 

 microscope reveals granules of a peculiar type. In polarised light 

 they are distinguished by a black cross, the characteristic feature of 

 starch, and that is confirmed by iodine, which colours the contents of 

 the granules blue. Whether we take a grain of buckwheat, a grain 

 of barley, or a potato, their examination would lead to the same 

 result. But their composition varies considerably in other respects. 



