TULIP DROPPERS ' 469 
It is precisely this last mentioned method of growth that 
regularily occurs in the formation of a new bulb in a vegetative 
plant of the tulip (see figs. 10 and 13). The radial growth of 
all nodes and internodes is eccentric; the increase in diameter 
of the node of the green leaf is much greater than that which 
the node immediately below made. None of the internodes 
elongate much except the one directly below the green leaf 
and in this one the elongation is unequal and is codrdinated 
with the eccentric growth of the node above. Viewed from 
below the surface of this, the internode is crescent shaped in out- 
line and the form of the entire internode is that of an asymmetri- 
cally truncated cone. It is from its crescent shaped surface 
that the new crop of roots emerge. 
If now the internode immediately above the leaf node also 
makes an unequal elongation coérdinated with the growth of 
the leaf node, then the conditions which make a dropper are 
realized (see diagrams 18, 19 and 20). The excessive unequal 
elongation of the two internodes is on opposite sides of the 
Same stem and these come to lie parallel to each other along 
the node which has made the extremely asymmetrically radial 
growth. The node and the internodes thus become drawn out 
into a long ribbon-like structure of stem tissue. The base of 
the green leaf remains attached at all points of the periphery 
of the node and its growth is so codrdinated that no lesions 
result. The region of greatest active growth in the stem portion 
of the dropper lies just behind the bulb in the region indicated 
by the dotting in figure 20. 
During the earlier part of the spring season of growth, about 
March 20 to 30 at the New York Botanical Garden, a plant 
which is burying its bulb appears as shown in figures 6, 7, 8 
and 9. The apex of the dropper with the main bud enclosed 
protudes through an opening that it has forced through the 
surrounding scales which at this stage are still fleshy. In 
every instance thus far observed by the writer the dropper 
broke through the fleshy scales along the line of their juncture 
with the stem and emerged at the lowest point of position 
(see figs. 1, 2, 3, 6, 7, 8, 9 and 11). 
