7(5 



KNOWLEDGE 



[Ai'BiL, 1902. 



truth ros]>iratorj. Whatever the ri<,'ht exjihiuation may 

 be, Dr. Dolirn was eueourafjeii in his view of the matter 

 hj an incideuta.! result to which other investigations gave 

 rise. He cut in two a. specimen of his .species Burana 

 riiftilli, for the sake of examining its anterior half. The 

 remnant, which eonqiri.sed the last three pairs of legs, 

 was thrown back into the water. To his astonishment 

 this (liiiiidinta Baraiia, this headless section, the brainless 

 hinil-quarters of an animal, " lived for many weeks, the 

 movement of the fluids of the intestine and body went 

 regularly on, the creature moved its limbs completely like 

 an luidamaged sjiecimen, even the eggs appeared to grow 

 more and more mature." Once again it must be allowed 

 that if not the wholly unparalleled, at least the very much 

 unexpected had come to pass. In detachment the leg 

 of a " harvestman " (Phalangium) by its long-continued 

 twitchings presents an uncanny and reproachful appear- 

 ance, but that is only faintly comparable with the spook- 

 like behaviour of this Barana, which walked and all but 

 talked weeks and weeks after its head was cut off. 



VEGETABLE MIMICRY AND 

 HOMOMORPHISM.-II. 



By Rev. Alex. S. Wilson, m.a., b.sc. 



The curious shapes of some exotic orchids are probably 

 advantageous from their resemblance to insects and 

 birds. One of our native orchids IJsfrea uvnfn has a 



Fig. 3.— Orchid and Beetle. 



flower which in shape decidedly resembles a species of 

 beetle, Gramninptera heri.^, by which it is fertilised. 

 Perliaps in this case the insect mimics the flower, as 

 certainly happens with a pink-coloured Mantis in Java, 

 which so exactly resembles a pink orchid that butterflies 

 are attracted to it in mistake. The insect is carnivorous, 

 and lies in wait for its prey, which is easily secured 

 by the help of this strange disguise. Mutual resem- 

 blances of this description are rather characteristic of 

 the Orchidacese. From their resemblance, real or fanci- 

 ful, to butterflies, moths, bees, spiders, &c., various species 



m 



FlO. 4. — Orchids re.-seniblinf; Insects. 



of Jl iihrnrnid, .Xrotiiiin and Oplinj.-: derive their names 

 the butterily, spider, bee and fly orchises. 



In the orcliid Ophryu munrifera are two little pro- 

 tuberances regarded by the late H. Miiller as pseudo- 

 nectaries. Of this class of deceptive contrivances, how- 

 ever, we have a i)ett.er example in PariiaKsia pal u Hit-in, 

 one of the saxifrages. This flower ha.s five fan-like scales 

 alternating with the stamens; the margins of the scales 



Fig. 5. — Pseudo-nectaries of Parnassia. 



are fringed with hair-like processes, and each hair is 

 capped with what appears to be a drop of honey. These 

 ai-o really hard dry knobs, but so much do they resemble 

 drops of honey that flies lick them before discovering 

 the imposture. The intention of these sham nectar- 

 drops may either be to decoy unpi-ofitable guests from 

 the real nectar, of which a limited supply is produced 

 in the hollow of each scale, or to advertise it for the 

 benefit of the more intelligent visitors. 



Somewhat analogous to these pseudo-nectaries are the 

 greenish swellings which arise on the veins of the petals 

 of Eremurus. These little swellings present a striking 

 resemblance to aphides or plant^lice, and Kemer states 

 that a fly accustomed to hunt after aphides pierces and 

 sucks the swellings, apparently mistaking them for the 

 insects. 



Relations which remind us of the pink orchid and 

 Mantis mentioned above, seem to exist between the little 

 bladders of Utricuhirin and the entoniostracans. The 

 bladder-wort is a carnivorous plant with small sub- 

 merged vesicles in which minute insects and entcmo- 



FiG. 6. — Bladilcrwort and Entoniostracans. 



stracans are caught. In shape these little traps of 

 Utricularia are not unlike the body of a crustacean ; 

 the stalk corresponds to the tail, and near the entrance 

 of each bladder are several antcnnre-like filaments so 

 resembling certain appendages of the crustaceans that 

 they impart to the structure a ludicrous resemblance to 

 su(-h an entomostracau as Daphne. 

 This curious likeness was remarked 

 by Mr. Darwin and can hardly be 

 altogether accidental ; perhaps the 

 prey is more readily induced to 

 ap]iroach the snare by reason of the 

 rosemlilanee. Here also may be men- 

 tioned the imposture practised on its 

 victims by Darlingtonia, another 

 insectivorous plant. In the hood of 

 its pitcher-like leaf are several trans- 

 parent spaces through which the light 

 shines into the interior ; to these the 

 imprisoned flies are attracted and 

 thereby diverted from the only open- 

 ing through which escape is possible. Mistaking the 



Fio. 7. — Leaf pitcher 

 of Darlingtonia. 



