440 Robertson . — The ‘ Droppers' of Tulipa and Erythronium . 
Figs. 7 and 8. Erythronmm americanum. 
Figs. 7 a and b. Young bulb (February, 1904). Fig. 7 b. Longitudinal section showing lateral 
bulb within the tubular base of the foliage leaf which will later form a dropper. 
Fig. 8. Older bulb (April, 1904). Two droppers have grown out. 
PLATE XXXII. 
Fig. 9. Tulipa sp. (Calcutta). 
Fig. 9 a. Seedling (Nat. size). 
Figs. 9 b , c, d t e. Transverse sections showing the vascular connexion of cotyledon, main root, 
and dropper ( x 146). 
Fig. 9 b. Cotyledon near base showing two bundles with a common protoxylem group. Outer 
parenchyma and epidermis omitted. 
Fig. 9 c. A little lower than Fig. 9 b , showing a branch going off to the dropper from each 
limb of the double bundle. 
Fig. 9 d. Diarch root on the right formed from the main part of the cotyledon double bundle, 
and dropper vascular system on the left formed from the two branches named d. v. b. in Fig. 9 c. 
These at first unite into a V-shaped double bundle, which in this section is beginning to divide up. 
On the right the first adventitious root is coming off. 
Fig. 9 e. Dropper and root quite separate. The vascular system of the dropper now consists of 
a midrib and two laterals. 
Fig. 10. Erythronmm grandifiorum. 
Fig. 10 a. Seedling. .j = seed. (Nat. size.) 
Figs. 10 b, c, d, e. Transverse sections showing relation of vascular system of cotyledon, root, 
and dropper. Outer parenchyma and epidermis omitted, i. v. b. = inverted vascular bundle ; l x and 
/ 2 = lateral bundles ( x 146). 
Fig. 10 b. Near base of cotyledon. 
Figs. 10 c and d. Transition region, d.m.r. — dropper mid-rib. 
Fig. to e . Triarch root completely formed to the right and dropper vascular system to the left. 
r. c. = root cylinder. 
Fig. 11. Tulipa sp. (Gesneriana ?). Flowering tulip with a dropper from one of its lateral 
bulbs (July, 1906). f st. — flowering axis. (£ nat. size.) 
