Francis E. Lloyd —120— Carnivorous Plants 



was measured manometrically at 27° C. The rate was constant over a period of six hours, 

 at the end of which one leaf was fed with a fly and some egg albumen, while another was 

 kept as a control. Repeated measurements over a period of some 20 hours following the 

 feeding showed that the control leaf maintained a practically constant rate of both pho- 

 tosynthesis and respiration. The rate of oxygen production of the experimental leaf 

 appeared somewhat depressed, but its respiratory rate was considerably higher than that 

 of the control. By correcting the photos3Ti thesis measurements for respiration in the 

 usual way it was found that the corrected values do not differ significantly from the orig- 

 inal ones. The increased respiration obviously resulted from the availabiUty of substrates 

 for oxidation on the outside of the leaf, and may be caused by the plant itself or by con- 

 taminating micro-organisms. These experiments lend no support whatever to the idea of 

 an influence of feeding upon the rate of photosjm thesis of carnivorous plants." (C. B. van 

 NiEL, in ep.). 



The appendages of the leaf. — There are several kinds of appendages 

 but they are not all common to all species of Drosera. Some are im- 

 portant physiologically in relation to the carnivorous habit, others not. 

 To the former belong the tentacles and sessile glands, common to all 

 species; to the latter are the glandular and eglandular trichomes seen 

 in D. rotundifolia and other N. hemisphere species and the glandular 

 trichomes found in such species as D. gigantea, and distributed over 

 the whole plant body (75 — 16). We may add, at this point, that 

 the fringes of trichome-like structures were regarded collectively as a 

 ligule by Nitschke. It is a fringed membrane formed at the sides and 

 across the leaf base in D. rotundifolia and some other species {16 — 18), 

 but is absent from many others {D. Whittakeri, D. peltata, D. gigantea, 

 etc.) It has been regarded as stipular and is so called in the taxonomic 

 literature (Diels) though Small (1939) takes another view, that the 

 apparent membrane is merely a linear cluster of trichomes. That 

 similar trichomes are found abundantly on the rest of the petiole sup- 

 ports his contention. On the other hand it is difficult not to see in 

 the huge ligulate "stipule" possessed by some species {D. paleacea, 

 D. pygmaea) {16 — 18) in Australia, in which they serve to protect 

 the bud during periods of drought (Diels), an integration of a fringe 

 as it occurs e.g. in D. rotundifolia. 



Tentacles. — Of these, the stalked glands or tentacles are the most 

 conspicuous and have most frequently been described. They have often 

 called forth exclamatory remarks of wonder at their complex structure. 

 They have been described, but not always correctly, by Gronland, 

 Trecul, Nitschke, Warming, Darwin, Huie, Fenner, Homes and 

 probably others. The tentacles occur on the margin and upper surface 

 of the leaf blade and in some species on the tapering upper region of 

 the petiole, excepting those species which are strictly peltate. 



The "tentacle" consists of a tapering stalk topped by an oval gland. 

 The stalk arises from the leaf surface, as a mass of tissue including all 

 the elements of the leaf structure, epidermis, parenchyma and vascular 

 tissue. The terms "trichome" and "hair" are therefore not suitable, 

 though they have been used. 



The term "tentacle" is not a strict one; it has been equated with 

 "emergence" and serves if we think of the tentacle as an extension 

 of the leaf adapted to certain functions which makes'them so trichome- 

 like that they are no longer distinguishable from trichomes (Diels). 

 Nitschke and others regarded the tentacles as extensions of the leaf, 

 Warming as trichomes and Penzig as intergradients between 

 phyllome and trichome. 



