SEEDLINGS. 95 
causes and effects are co-related; that, for instance, an emarginate 
or lobed cotyledon is often coincident with a smaller or greater in- 
growth at the chalaza; that narrow cotyledons are often present, 
where for some reason there is not an easy exit from the seed; and 
in the endosperm, they would probably have never got free, but 
been torn from the axis, as does actually happen in a species of 
dnona figured on p. 104. Even supposing that many of the 
theories were not wonderfully suggestive, and that every explana- 
tion were untenable, we should still have about a thousand pages 
each family is an so toduaboree Seay in which are described the 
forms of fruit, seed and embryo occurring therein, and also of the 
cotyledons observed among the seedlings. Where possible, both 
Chaeuhes oe heiri, Al aie Ded at Hesperis nivea, Conringia 
perfoliata, Camelina sativa, Biscutella didyma, Lepidium graminifolium 
and spinosum, Iberis corifolia and wee tenella; and with slight 
modification, dithionema gracile and Iberis Lagascana ; the second 
type with bro ad and emuarginate cotyledons is ‘almost as widely 
distributed catch eon the Order 
Fundamental differences sometimes occur, even between species 
of a genus. Thus ere is a striking contrast between ogi 
of a hypogeal and epigeal nature: in the former they are fleshy, 
PSR and fill the seed in which they cuales serving merely 
as a store of food for the wabrie © seedling, while in the latter 
green, and loo and penaxe like an ordinary eaf. Clematis recta, 
leading types: seedlings with et and seedlings with sub- 
terranean cotyledons ; Rhus Thunbergiana is a good example of the 
latter, and Rhus typhina of the former. The same is noticed 
among the Ph aseolew, where the genera Phaseolus and Hrythrina 
both supply species illustrative of each class; but here the aerial 
cotyledons are not strictly foliaceous, remaining pale and fleshy and 
often turned to one side of the stem. ‘The horse-chestnut is in- 
