26 
of the same plant they should, apart from slight differences 
of nutrition, not only be all similar but actually of the 
same constitution. “It is true that bud variation does 
occasionally arise in plants, but it is a comparatively rare 
phenomenon, and consequently we find that as a rule 
plants, raised by vegetative methods, maintain the char- 
acter of the parents and do not show the sporting with 
which one is familiar when raising plants from seed. THe 
purity of the strain is thus easily maintained by vegetative 
propagation. 
Let us now examine some of nature’s methods of 
vegetative reproduction. In the first place, we have such 
well-known examples as tubers which form the chief 
method of propagation of the potato and of the Jerusalem 
artichoke. A tuber is the swollen-up end of an under- 
ground branch. This can be clearly seen by digging up 
a young potato plant and following these subterranean 
shoots from the parental stem to their tuberous tip. Both 
the branch and also the tuber show the rudiments of 
leaves, reduced to small scales and spirally arranged 
round the potato. On an old potato the sickle-shaned 
mark below each eye or lateral bud represents the insertion 
of the leaf or leaf scar, and at one end of the potato where 
these become more crowded together, we have the terminal 
bud of the tuber. This is called the “rose” end. At the 
opposite end we can generally find the scar or heel where 
the branch of which the tuber is the dilated tip, was joined 
to it. In all cases tubers are filled with stored food 
material, mainly starch in the case of the potato. When 
potatoes are set in the spring, the terminal bud grows 
up to form the main stem of the new plant, while the 
other eyes remain generally dormant. The new tubers are 
formed from specialised underground branches produced 
from the lower region of thc main stem. The latter is 
therefore often earthed up so as to promote the develop- 
ment of these side shoots. It is a very common practice 
before setting potatoes, to place them side by side with 
the “rose” end uppermost and allow the terminal shoot 
to commence its development in daylight. By this means 
the shoot does not elongate so rapidly as when grown > 
underground, that is, in the dark, and thus the lateral 
buds, which will develop into tuber producing shoots, are 
morc closely crowded together and more numerous. This 
method therefore results in a greater vield of new tubers. 
