Robertson. — The ‘ Droppers' of Tulipa and Erythronium. 439 
EXPLANATION OF PLATES XXXI AND XXXII. 
Illustrating Miss A. Robertson’s paper on the ‘ Droppers J of Tulipa and Erythronium. 
f — foliage leaf; d. = dropper ; d.b . — tip of dropper containing bulb ; d.w. — dropper wall ; sc. = 
scale leaf; Lb. lateral bulb; st.= dwarf stem; v.b. = vascular bundle; m.r.— midrib; d.m.r.— 
dropper mid-rib; d.v.b. dropper vascular bundle ; x. = xylem; ph. = phloem; r. = main root; r v ~ 
first adventitious root; adv. r. = crop of adventitious roots ; c = cotyledon. 
PLATE XXXI. 
Fig. 1. Bulb of Galanthus nivalis (June, 1903) showing prolongation of axis, and formation of 
new bulb some little distance from parent (Nat. size). 
Fig. 2. Non-flowering plant of Tulipa saxatilis (March, 1902). 
Fig. 2 a. Whole plant (f nat. size). 
Fig. 2 b. Bulb with outer scale leaf removed (Nat. size). 
Fig. 2 c. Bulb with inner scale leaf and axillary bulb removed, showing continuity of base of 
foliage leaf and dropper (Nat. size). 
Fig. 2 d. Longitudinal section of tip of dropper showing bulb (slightly enlarged). 
Fig. 2 e. Transition region of foliage leaf, stem, and dropper in carbolic acid to show veining 
(slightly enlarged). Three main veins run up the back of the leaf from the stem base. The 
bundles supplying the adaxial side of the dropper all arise as branches from these three. 
Fig. 3. Diagram to represent the mode of origin of the dropper of Tulipa by invagination of 
the tubular base of the foliage leaf fused on one side with an outgrowth from the stem. The stem 
is distinguished by cross-hatching. 
Fig. 4. Tulipa Clusiana (December, 1903). 
Figs. 4 a, b, c } d. Stages in the dissection of the bulb (Nat. size). Fig. 4 d. shows a small 
dropper forming the continuation of the foliage leaf. Also a lateral bud. 
Figs. 4 e,f, g, h. Diagrams of sections cut at the levels marked by these letters in Fig. 4 d. 
The bundles are not yet completely differentiated into xylem and phloem (x 13 circa). 
Fig. 40. Section at the level at which the tabular cavity of the leaf base opens to the exterior. 
Fig. 4/. Section near top of lateral bulb. 
Fig. 4g. Section through attachment of lateral bulb. Bundles are passing from the stem into 
the dropper. 
Fig. 4 h. Dropper free from stem. Note circle of bundles on adaxial side. Bundles in stem 
rudiment are becoming irregular. 
Fig. 5. Tulipa saxatilis (March, 1902). 
Fig. 5 a. Central part of bulb showing rudimentary stem to which is attached base of foliage 
leaf, dropper, and adventitious roots (Nat. size). 
Fig. 5 b. Section at the level marked B in Fig. 5 a, showing dropper and bases of numerous 
3- to 5-arch adventitious roots, embedded in the rudimentary stem. 
Fig. 6. Tulipa praecox (March, 1902). 
Figs. 6 a , b, c, d, e. Dissection of bulb by removal of successive scale leaves. This bulb has 
a dropper in connexion with its foliage leaf, and also a second dropper from a lateral bulb. The 
second dropper is slightly connected with the outer tissues of the first. 
Figs. 6 /, g, h. Three views of the transition region of the leaf and main dropper in carbolic 
acid (slightly enlarged). Five veins on the midrib side of the leaf run straight into the stem 
rudiment, and four veins on the sheathing side run straight into the abaxial side of the dropper. The 
fifth vein on the sheathing side of the leaf connects with an arch from the stem rudiment, and does 
not continue down into the dropper. Some veins come' straight from the stem rudiment and run 
down into the back of the dropper which is also partly supplied by branches from the five main 
leaf veins. 
Fig. 6 k. Apex of second dropper in carbolic acid (slightly enlarged). 
