Robertson . — The ‘ Droppers' of Tulipa and Erythronium. 431 
have been investigated by Mr. Woodhead l , both as regards their behaviour 
and internal structure. 
Among the Lilioideae we meet with a great range of bulb structure. 
Perhaps the most primitive type of bulb is that of such a plant as the 
White Lily, in which the scales are obviously leafy, the outer ones being 
actually formed from the bases of the foliage leaves. A slightly more 
advanced stage is reached in the Turk’s Cap Lily (L ilium Martagon ), in 
which there are no ground leaves, and so all the bulb leaves, not merely 
the inner ones, take the form of specialized scales. A much more sophisti- 
cated type is that of the so-called Tunicate bulb,’ in which each scale leaf 
is a closed sheath, with only a small opening at the top. The most specialized 
methods of descent into the soil with which we are acquainted are met with 
in Scilla, Tulip a , and Erythronium among the Lilioideae, and Gagea among 
the related Allioideae, all of which have tunicate bulbs. The curious 
behaviour of the Wild Hyacinth is described by Rev. C. Wolley Dod as 
follows : — 4 The smallest bulbs, which I take to be the produce of the seed 
shed eighteen months before, in the July of the previous year, are at 
a depth of one or two inches, and the size of a small pea ; the two-year- 
olds are at an average depth of four inches, and at least 70 per cent, of 
them are curiously elongated, being three times as long as broad. Those 
three and four years old — for I think some rest contented with the depth 
reached in the third season’s growth, and some take another dive in their 
fourth season — are six or seven inches deep. Thus the crown of the new 
bulb is, on an average, \\ inch below the base of the old one, and I feel no 
doubt that it is formed where it is found.’ Mr. Woodhead 1 has published 
a full and interesting account of the life history of the Wild Hyacinth, 
and the structure of the curious elongated bulbs by which it lowers itself 
into the soil. 
The most highly specialized method of descent, that by ‘ droppers,’ is 
discussed in detail in the following sections. 
III. Tulip ‘ Droppers.’ 
Tulip growers have long been familiar with e droppers ’ (‘ sinkers ’ as 
they are called in Holland), and a good many accounts of them and 
references to them occur in horticultural and botanical literature ; but it will 
be convenient to leave the discussion of these until after the description of 
my own observations. 
(a) The Non-Flowering Tulip. 
Fig. %a shows a typical, immature, non-flowering plant of Tulipa 
saxatilis, in the state in which it would be found about March. The 
1 T. W. Woodhead, Notes on the Bluebell {Scilla festalis, Salisb.), The Naturalist, Feb. 
and March, 1904. 
