Francis E. Lloyd — 254 — Carnivorous Plants 



It is of interest and mere justice to record that the velum had been 

 seen previously by two observers, both in 1891. Giesenhagen, I be- 

 lieve it was, made a drawing for Goebel's paper of 1891 of a trans- 

 verse section of the threshold of U. flexuosa. In this drawing the velum 

 was shown in the clearest manner, but no mention of it was made in 

 the text. And in 1891, at Cambridge (England) R. E. Fry, a student 

 who was later to become an eminent art critic and Professor of Art 

 in that university, and who is better and more widely known as 

 "Roger Fry," prepared a Ms. which was never pubhshed, but to 

 which I fortunately had my attention drawn when attending the 

 International Botanical Congress in 1930. It was lying on the shelves 

 of a bookshop. Roger Fry was evidently a close observer, for in one 

 of his drawings, meticulously executed in fine pencil and color, he 

 showed the velum, and in his description he described the pavement 

 epithelium (he used Goebel's 1891 term), saying that "the whole of 

 this secretes mucilage, the cuticles of the hairs being raised in a mass;" 

 but he did not examine further into the matter. One cannot help 

 wondering why others, who saw other minute details, failed to see the 

 velum. Roger Fry's Ms. has now been deposited by me in the 

 Library of the School of Botany, Cambridge University. 



Two mechanical types of trap. — Having described in some detail 

 the structure of the trap of Utricularia vulgaris, it must now be pointed 

 out that, though working according to the same mechanical principles 

 and being of the same morphological type, there are two distinct kinds 

 of traps (Lloyd 1936c). They can be distinguished readily by the 

 posture of the door in its relation to the threshold (Text fig. 9). If we 

 consider the entrance as tubular, in one kind the tube is short, in the 

 other long. U. vulgaris has a trap with a short tube entrance. In it 

 the door stands approximately at right angles to the axis of the tube, 

 or at any rate forming a wide angle with it. In the other kind, of 

 which U. capensis is a good example, the entrance is tubular (Ste- 

 phens 1923), and the door stands obhquely, forming a narrow angle 

 with the axis. Considered as a valve, this is the less efficient, ceteris 

 paribus, but its inferiority is compensated for in various ways, to be 

 noted. Of the latter kind there are two variants represented by such 

 species as U. monanthos, and U. dichotoma, on the one hand and Poly- 

 pompholyx on the other, all purely Australasian types, with differences 

 demanding separate description. 



The description of U. vulgaris above given will serve as a standard 

 of comparison. Correlated with its position in the short tubular 

 entrance, the shape of the door is such that its sagittal measurement 

 is less than its transverse. The top of the threshold is narrow. In 

 U. capensis, with a long tubular entrance, the door has reversed 

 measurements: it is longer than broad, and the threshold is broad 

 (29 — 12, 13). The door stands obhquely. A glance at the diagram 

 (Text fig. 9) will reveal these differences. It is seen that, considered 

 as a check valve, the long door, presenting a re-entrant angle with the 

 threshold, and with no opposing seat, is, with respect to the direction 

 of the water pressure, at a disadvantage. In our blood vessels the 

 valves, which are also obliquely set flaps, are in the reverse position. 

 But from the point of view of the efficacy of the trap, the door would 



