1024 



THE NATURE BOOK 



one and a half to three minutes, and if 

 a leaflet should be restrained for a while, 

 the rate of travelling is very much 

 increased. Although it is nothing like 

 so perceptible, the larger leaflets also 

 change their position, moving first to the 

 right, and then to the left, with a slow, 

 continuous movement. The most singu- 

 lar point about the jerks of the leaflets 

 of the Telegraph Plant is that they seem 

 to occur quite spontaneously, and not 

 in reponse to any external stimulus. 

 The explanation of this strange pheno- 

 menon is still wanting, neither is it easy 

 to see that the plant derives any beneiit 

 from its remarkable habit. Specim.ens 

 of the Telegraph Plant are to be seen in 

 most botanical gardens. 



Among the insectivorous plants there 

 are to be found some striking instances 

 of plant sensation ; indeed, certain of the 

 species are very highly specialised in this 

 direction. The Droseras, or Sundews, 

 are well-known little plants found in 

 various parts of the world, the genus 

 being represented in Great Britain by 

 three examples. The Round-leaved Sun- 

 dew {D. rotiindifolia) is found commonly 

 in boggy places. The plant, although 

 small, is rendered somewhat conspicuous 

 on account of its rosettes of bright-red 

 leaves. It is worth while to examine 

 the foliage rather closely. The leaves are 

 seen to be covered with clubbed hairs, 

 at the ends of which are produced sticky 

 glands. 



It is strange that the foliage of the 

 Sundew seems to have a peculiar fascina- 

 tion for flies and other insects, all^cit that 

 these little creatures as a rule, pay a 

 heavy penalty for their curiosity. So 

 sensitive are the hairs on the Sundew 

 leaf that the struggles of a fly held by 

 the sticky secretion induce the processes 

 to close round the unfortunate victim, 

 so that escape is quite out of the question. 

 At the same time these movements are 

 accompanied by an excretion of a diges- 

 tive fluid which aids the leaf to assimilate 

 the nitrogenous matter in the body of the 

 fly. Another curious feature in the 

 behaviour of the tentacles of the Sundew 

 leaf is that they entirely fail to respond 

 in any way to drops of water which are 

 allowed to fall on the foliage. As well, 

 too, it is remarkable to note that althougli 



small stones may be enclosed by the 

 tentacles, 3'et in these instances there is 

 no discharge of the digestive fluid. 



Even more remarkable than the Sun- 

 dew is the Venus Fly-trap {Dioncva 

 ynnscipitla), a little plant which is a native 

 of the swamps of North Carolina. The 

 leaves of this plant, which mostly lie out 

 flat on the soil, are composed of two 

 very distinct parts, a stalk and a blade. 

 The stalk, a leafy expansion which really 

 performs the functions of ordinary foliage, 

 is joined to the blade by a narrow neck. 

 The blade is formed of two plates which 

 are united by a rib fashioned somewhat 

 on the lines of a hinge. The outer edges 

 of the plates are furnished with borderings 

 of rough bristle-like hairs. The sensitive 

 part of this little trap exists in three 

 cilia arranged in triangular fashion on 

 each half of the blade. To touch one of 

 these ever so lightly is to induce a rapid 

 closing of the little apparatus ; the plates 

 snap up together, the fringe of hairs 

 interlocks — the whole proceeding strongly 

 suggesting the shutting of a very per- 

 fectly contrived trap. 



Now, if the object which comes into 

 contact with one of the sensitive hairs 

 should happen to be a fly, the 

 result is, of course, disastrous for the 

 unfortunate insect ; no escape is possible 

 for the victim, whose body will be retained 

 by the Dionsea leaf until the desired 

 nutrient properties have been absorbed. 

 In order to attract the flies, it .ippears 

 that the upper surfaces of the plates are 

 furnished with certain small glands which 

 secrete a viscous fluid peculiarly alluring 

 to insects. It is singular that no other 

 part of the leaf of the Venus Fly-trap is 

 at all responsive to contact. The back 

 of the organ, even the surface of the 

 plates themselves, may be touched ; 

 but unless one of the bristles is jarred the 

 little trap remains immovably open. 

 Experiment with this strange plant showed 

 that whilst the blades would enclose 

 small pieces of stone, for instance, yet 

 these would not be retained for any 

 length of time. A short while after 

 acceptance, the blades will slowly open 

 and permit the unwanted sub tance to 

 roll away. 



There is no doubt that there is a great 

 deal in the behax-iour of roots which it is 



