The "Droppers' of Tulipa and Erythronium. 
BY 
AGNES ROBERTSON, D.Sc. 
Quain Student in Botany , University College , London. 
With Plates XXXI and XXXII. 
I. Introduction. 
I N the course of Miss Ethel Sargant’s examination of monocotyledonous 
seedlings, she noticed in the Tulip and Dog’s Tooth Violet the peculiar 
descending stolons known to gardeners as £ droppers.’ These seemed to 
show features of some interest, and since the question lay outside the main 
line of her research, she proposed to me early in 1902 that I should find 
out what work had been done on the subject, and try to investigate it 
further. I am indebted to Miss Sargant not only for suggesting this 
research, but also for handing over to me her Tulipa and Erythronium 
seedlings, and allowing me to examine her preparations of these genera. 
I have also to thank Mr. R. I. Lynch, M.A., of the Botanic Garden, 
Cambridge, and Mr. E. Aveling Green, of Berrystead, Beds, who have been 
most generous in supplying me with material and information. This 
investigation has been carried out in the laboratory of University College, 
and I have much pleasure in acknowledging the kind help I have received 
from Professor F. W. Oliver, especially in connexion with the literature. 
II. The Movements of Bulbs in the Soil. 
(a) Migration. 
A great drawback of the vegetative reproduction so characteristic of 
bulbous plants is that it tends to overcrowding. The lateral bulbs are 
produced close together, and have no opportunity of colonizing fresh soil. 
This is got over in certain special cases by the replacement of sessile by 
stalked bulblets. De Vriese 1 records cases in which Ixia lutea and carminosa 
produced their lateral bulblets at the end of stalks from 1 to 15 centimetres 
1 W. H. de Vriese, Bydrage tot de Morphologic der Bollen, Tydschr. v. Natuurlyke 
Geschiedenis, Leiden, 1841. 
[Annals of Botany, Vol. XX, No. LXXX. October, 1906.] 
