Anatomy and Morphology of Utricularia brachiata. 127 
doubt that this view is untenable, owing to the innumerable 
transitions which are found between runners and “ leaves,” and the 
fact that bladders are found indifferently on both forms of organ. 
The conclusion is irresistible that both runners and “leaves” belong 
to the same morphological category. The alternative views we 
have to consider are briefly :— 
1. The “leaves” are of the nature of phyllomes and the 
creeping runners are specialised leaves. 
2. The runners are caulome structures, and the “ leaves ” have 
been derived from similar organs by a process of flattening. 
The arguments for the former view, stated by^ Goebel, depend 
primarily on a supposed analogy between the bladders of Utricularia 
and the remarkable tubes or utricles of the closely allied genus 
Genlisea. As Goebel remarks, there can be no doubt that the tubes 
of Genlisea are modified leaves. 
These tubes are curious forked structures with a highly developed 
eel-trap arrangement for catching small animals. The structure of 
these utricles, as Charles Darwin called them, has been thoroughly 
investigated, 1 and there is no need to enter into it here in detail. 
These eel-trap structures have been generally assumed to be 
homologous with the bladders of Utricularia. It appears, however, 
that they may well be of quite distinct origin and nature. It is very 
difficult to imagine the mode in which the transition from one form 
of trap to the other could have been effected. Both bladder and 
utricle are well-defined and highly specialised organs, and the range 
of variation in the two genera in the essential features of each form 
of apparatus is relatively small: variations in form of the upper lip of 
the Utricularia- bladder are abundant, and the details of arrangement 
of the trichome structures shew some diversity in the different 
species ; but there exists (so far as is known) nothing, normal or 
teratological, which points to any direct transition from such bladders 
to the utricle of Genlisea, or vice versa, or to the derivation of both 
bladder and utricle from an intermediate ancestral form. Another 
fact which supports this position is that the utricle of Genlisea is, 
as regards the leaf from which it was derived, a terminal structure ; 
whereas the U tricularia-bladdev is borne laterally. Though this is 
1 F. Darwin in C. Darwin's “ Insectivorous Plants,” 2nd Revised 
Edition, 1893, p. 360, et seq. 
Goebel. “ Pflanzenbiologische Schilderungen,” II. (1893), p. 121. 
,, Flora LXXVII., 1893, p. 208. 
Warming. Vidensk. Meddel. Nat. For. Kjobenh., 1874, 33, t. 5, 6. 
,, Ann. Sc. Nat., ser. 2, XI., p. 165, t. 5. 
