Recent Agricultural Puhliccotions. 
831 
enormous destruction of seeds. The great majority are eaten by animals, 
or fail to secure a suitable site for germination ; of those which do 
germinate, again, many are crowded out by their fellows. Darwin ob- 
served that, out of 357 seedlings which came up in a space of three feet by 
two, no less than 295 were destroyed by slugs and insects. Now the 
greater the chance against any given seed reaching any suitable locality 
and attaining maturity, the larger number of seeds must the plant produce 
in order to maintain its numbers, and, as a general rule, the smaller will 
the individual seeds be. On the contrary, the greater the chance that 
each seed enjoys of arriving at maturity, the smaller the number of seeds 
that is necessary, and in such cases it is an advantage that the seeds should 
be large. 
“ Hence parasitic plants generally produce a large number of vei’y small 
seeds, though there are exceptions due to other considerations, as, for instance, 
in the Mistletoe (I believe, indeed, in all the Loranthacese), where the 
seeds are carried by birds.” 
Every ripe seed contains an embryo which, under suitable 
conditions, is capable of growing into a plant like the parent plant. 
In some seeds, called exalhimiinous seeds, such as Bean, Pea, Clover, 
Turnip, Cabbage, the embryo occupies the whole of the inside of 
the seed. In others, such as Parsnip, Mangel, Wheat, the 
embryo does not occupy all the inside of the seed, the space being 
filled up with nutritive material called endosperm ; such seeds are 
described as albuminous or endospermic. In seeds of the latter type 
the arrangement of the embryo within the seed presents no special 
difficulties, as the endosperm simply fills up all vacant spaces. 
In the exalbuminous seeds, on the other hand, “ Nature has to ex- 
ercise much ingenuity, and adopts various devices to fill up the 
whole space.” One plan is to arrange the cotyledons face to face, 
and then roll them up into a ball ; on this principle the long strap- 
shaped cotyledons of the Sycamore are explained. Another method 
is again to arrange the cotyledons face to face, but then to simply 
double them up, as in the Cabbage, Mustard, and Radish. 
Some seeds, it is well known, never push their cotyledons 
above ground. The explanation is thus given (vol. i., page 
58) 
“ In such cases as the Lupin (fig. 4) the cotyledons become so fleshy and 
thickened that they almost lose the appearance of leaves ; in this instance 
they are set free by the splittmg of the testa. When, however, the testa (or 
seed-coat) does not readily split, and where in large seeds there is no endosperm, 
the difficulty of unfolding the cotyledons and extricating them from the seed 
becomes greater, and we arrive at cases where Nature seems to have 
abandoned the attempt, and, as in the Oak and Horse Chestnut, the cotyle- 
dons never quit the seed. Thus, among the Juglandeae, Pterocarya 
has leaf-like cotyledons, while those of the Walnut never quit the shell. 
Everyone, however, must have observed the elaborate folds into which 
the two cotyledons are thrown, folds which seem to have no significance or 
importance now, and which carry us back to a time when the Walnut, like 
the Pterocarya, had foliaceous cotyledons.” 
Growers are aware from experience that some kinds of seeds 
“ come up ” sooner than other kinds. Here, the size of the embryo 
exercises an influence. It is obvious that, supposing different 
