26 
BULLETIN OF THE LABORATORIES 
In both direct and indirect superposition the bud first formed is the 
largest, the best developed, and the one most likely to grow and to form 
a branch. If several buds produce branches, those from the later 
buds are successively smaller. If the largest and earliest bud dies, 
the next in age takes its place and produces the branch. Insects fre- 
quently cause the death of branches ; early frosts may nip the tender 
shoot ; birds, squirrels and other animals frequently feed upon the buds 
themselves ; in all these cases the smaller, more undeveloped buds 
may come into play and be called upon to continue the life and growth 
of the plant. Superposed buds are thus a provision of nature to 
remedy the loss of buds or branches, however occasioned. Buds are 
usually formed a short time after the tissues of the leaves have become 
differentiated from the stem, and the ordinary scaly buds of ligneous 
plants can be seen in a rudimentary condition almost as soon as the 
leaves can be distinguished by the naked eye. By the time the leaves 
are fully developed the scaly buds have also reached a stage bordering 
on maturity, and this generally before the middle of summer. Be- 
tween this time and autumn they undergo a slow change and indura- 
tion which prepares them for winter. Superposed buds of the same 
axil originate at different times, but the bud first formed develops sub- 
sequently to the formation (differentiation) of the subtending leaf. 
The difference in time in the appearance of the several buds is some- 
times very slight, so that they seem to originate almost simultaneously. 
This is true of Gymnocladiis , in which, however, the difference in size 
is well marked at an early period. 
Superposed buds do not appear in all the axils of a plant ; it is 
even uncertain whether they can be found in all individuals of any 
single species. Nor do they always appear in equal numbers. The 
existence of accessory buds is a sign of vigor ; the leaf-axil does more 
than the normal amount of work whenever it produces more than one 
bud. The period of greatest vigor and most rapid growth is not 
when the plant is small and struggling for life, but when it has reached 
some size and has abundant roots. Accessory buds in herbaceous 
plants are usually found, therefore, in the upper axils of the plant, and, 
if more than two buds be found in any of the axils, the greatest num- 
ber will be found in the most vigorous axils. But these are not the 
axils last produced, because at this time of a plant’s history the flowers 
are being formed, a period just proceeding the plant’s maturity and de- 
cay, when there is not much need for accessory buds, unless it be to con 
