1 12 
GERMINATION 
plumule presently comes above ground, often bent back 
on itself into a hook-shape, and begins to develope into the 
young shoot. The cotyledons as a rule come up too, turn 
green, and act as the first foliage leaves, but if there is any 
endosperm they first of all act as absorbent organs to take 
up the reserves it contains. In a few exalbuminous seeds, 
e.g. pea, the cotyledons are so gorged with reserves that by 
the time they are exhausted the young plant is well enough 
grown to be independent, and there is no need for them to 
turn green, nor do they. Such also is the case in a few 
albuminous seeds, e.g. the Gramineae. 
Observations made by Detmer 1 on the heights, weights, 
&c., of plants grown from heavy and light seeds show 
that, other things being equal, the former are as superior to 
the latter as the offspring of cross- to that of self-fertilisation, 
so that this is a very important factor in the life-history. 
It might pay a plant, so to speak, to give up cross-fertilisa- 
tion and expend the saving on heavier or more numerous 
seed. As usual, a balance must be struck between opposing 
necessities ; the heavier the seed the less its chance of dis- 
tribution. 
An interesting point frequently seen in seedlings is the 
exhibition of transitional stages towards the mature state 
(p. 29). Good examples are Acacia, Bossiaea, Ulex, Hakea, 
many succulents, &c. 
Vegetative Reproduction. Frequently portions of 
the vegetative organs, specialised in structure or not, are 
detached and grow into new plants. The detachment need 
not precede the growth of the new plant, but may follow it, 
as in the case of the young strawberry-plants formed upon 
the runners. It is of interest to notice the various ways in 
which the young daughter-plants may be nourished. If the 
detached portion be not green, as e.g. a potato tuber, reserve 
materials must be stored up in it to start its growth and keep 
it growing until it can assimilate for itself, so that it is the 
physiological though not the morphological equivalent of 
a seed (gardeners speak of ‘ seed-potatoes ’). If the young 
plant, as e.g. in the strawberry, remain in connection with 
1 Detmer, Keimungsphysiologie ; Lubbock, Seedlings ; Goebel, 
Organography of Plants ; Vandevelde, De Kieming der Zaadplanten , 
in Bot. Jaarb., Gent, 1897 (literature list). 
