30 
BULLETIN OF THE LABORATORIES 
alba {2), C. sulcata^ C. totnenfosa and C. porcina^ all have the upper one 
of the two superposed buds so excessively developed, that the lower 
remains quite insignificant, often obsolete. C. miavcarpa and Juglans 
regia have the lower buds of larger size. Robinia Pseudacacia has 
two superposed buds, both of which often develop, but the upper one 
outgrows the other. In this species the buds are formed beneath the 
surface of the petiole scar, so as to be invisible until growth begins in 
spring. Sometimes three buds in one row are seen bursting through 
the scar which has encased them all winter. Menispermmn Cana- 
dense (17) has also two or three buds covered by the circular petiole 
scar, through which they burst in spring. Two of three buds 
often develop into branches. Gymnocladus Canadensis (6), which 
has buds enclosed by circular pit-holes in the bark, frequently presents 
four or five of these to one axil, the lowest being reduced to a mere 
dot. The upper two are always quite a distance apart — the lower 
ones less so. Sanibiicus, which is usually credited with the existence 
of buds inversely superposed, presents a poor case in S, Canadensis^ 
in which the lower buds seem to develop from the upper, and not to 
be independent of it. 
Various species of Rubiis also show superposed buds having the 
general aspect of those of Sambucus Canadensis. In some species 
which usually produce three or more buds in the same axil, the upper- 
most bud is greatly developed and often supported by a basal internode 
one-eighth to one-half an inch in length. Carya olivaeforniis (3) 
has two or three buds, the upper two well developed and some distance 
apart. The support of the upper is small, often obsolete. C. am- 
ara, with two or three buds placed closer together, has a support for 
the upper bud, often one-third of an inch long. In Ptero-carya 
Caiicasica (15,) we find the extreme in length of the support-one-half to 
three-fourths of an inch. Three buds are normally produced in the 
same axil. Liviodendron Tullpifera has three buds close together, 
the upper with a support often half an inch long. These species offer 
a sort of transition to those in which the upper bud develops immedi- 
ately into a branch. 
The only case among herbs, known to me, which would prop- 
erly fall under this class, is that of Dicentra Cncidlaria (9). The 
grains clustered about the roots of this plant are known to be 
either the bases of aborted leaves, or the true bases of the leaves 
themselves. Both kinds of grains, when sufficiently developed, will 
