REPRODUCTION 417 
that this is the regular method of the multiplication of the 
yeast-plant, where each division of the protoplasts brings 
into being a new individual. The process can be noticed 
through all the families of the vegetable kingdom, though 
as we advance upwards in the scale the separated body 
becomes more and more complex. We have the gemme- 
of certain Alge and Bryophyta, which are multicellular ; 
we have in certain Mosses branches which become detached 
by the dying off of the shoot behind them. Many Ferns 
develop buds upon the pinne of some of their leaves, 
which when separated from the latter grow into complete 
ferns. Among the Phanerogams we notice a great variety 
of this method of reproduction, many structures being 
developed normally to secure it, while others can be made 
to lead to it by artificial means. We have the propagation 
of plants normally by the formation and separation of 
tubers, buds, and corms; by the young plants which are 
developed from the nodes of runners and stolons. The 
artificial method of bringing it about is illustrated by cut- 
tings, which are pieces of the stem, bearing buds; these 
when detached and planted in suitable soil, put out adven- 
titious roots from the base of the cutting and develop into 
plants like the original one. Other instances are afforded 
by the buds which many leaves, notably those of Bryo- 
phyllum and certain Begonias, put out when wounded. 
These also develop adventitious roots, and young plants 
arise which become independent. 
This method, in which we never meet with the prepara- 
tion of cells which are specialised in the direction of 
reproductive powers, is usually spoken of as vegetative 
reproduction or vegetative propagation. 
Some curious cases of it are known. In the embryo 
sac of Calebogyne there is no fertilisation of a sexual cell 
in the manner which will shortly be described, but still one 
or more embryosarise. Thisis caused bya vegetative bud- 
ding of certain cells of the nucellus of the ovule, which grow 
into the interior of the embryo sac, and develop into embryos. 
27 
