Dec, 21, 1883.] 



♦ KNOWLEDGE ♦ 



371 



ending in two sharp points ; they move sideways and close 

 upon one another like a pair of shears. Next come a pair 

 of more delicate jaw-like organs, the maxillx', each of which 

 carries a large, jointed appendage, the maxillary palpiss, the 

 last joint, the largest, shaped something like an axe-head ; 

 these hatchet-like pieces are by far the most conspicuous ob- 

 jects in the head. Between the maxdlie Ls a thin plate, the 

 labium carrying another and smaller pair of jointed organ.s, 

 the labial palpi. Now the presence of the pair of horny 

 sheaths covering the transversely - folded membranous 

 wings, and tlie structure of the organs of the mouth, which 

 are adapted for biting, and not for sucking or licking 

 juices, are characteristics of the order of beetles ; and so, if 

 a stag-beetle, dung-beetle, Colorado beetle, or other member 

 of the order be examined, the wings and mouth will, as a 

 rule, be found to be constructed on the same plan. 



Like other beetles, too, ladybirds pass through a series 

 of remarkable transformations during their brief life. The 

 parent insect lays her yellow eggs on some plant infested 

 with aphides, or blight, as they are popularly called. From 

 the eggs emerge little six-footed creatures of a slaty colour, 

 sprinkled with yellowish dots, and further ornamented with 

 a number of warts or tubercles. They attack and make 

 short work of the aphides, and grow fat upon the diet. 

 But after a while, a great change occurs ; the grub becomes 

 transformed into a pear-shaped body, wholly devoid of 

 limbs, and attached by the smaller end to a leaf or 

 some other support. In this condition it remains for a 

 time perfectly quiescent ; then the skin bursts, and there 

 creeps forth a limping, soft creature, in form a ladybird, but 

 in consistency something like a boiled pea. Exposure to the 

 air after a time hardens its skin and at the same time 

 deepens its colour, and then we have the adult ladybird 

 fully equipped for setting about the great task of the per- 

 petuation of its kind. When on the wing it flies vigo- 

 rously, but it is a poor pedestrian, walkmg at no great rate 

 and with no very certain steps, and ready at slight provo- 

 cation to tuck its legs in close to its body and feign death, 

 in which condition it may be tossed about without manifest- 

 ing any signs of vitality. This is not its only means of pro- 

 tection, for it is able to exude a yellow oily fluid of power- 

 ful and rather ofiensive odour, and no doubt of equally un- 

 pleasant taste. This must make it an extremely nauseous 

 morsel to any foe that has the temerity to attempt to make 

 a meal of it. Not only during its grub-like babyhood is it 

 the ruthless destroyer of aphides, when it has assumed the 

 responsibilities of adult life the old taste still persists, and 

 the war of extermination is i)rosecutcd with vigour, those 

 bifid mandibles forming excellent weapons for tearing to 

 pieces the bodies of the sluggish but luscious plant-lice. 

 It must therefore be reckoned as one of our insect friends, 

 and its frequent presence in large numbers in hop-gardens 

 will be regarded with satisfaction, when we remember how 

 peculiarly lialjle the hop-plant is to the attacks of aphides. 



Our British fauna can boast of about a score of species 

 of ladybirds. Some of these are very abundant, others 

 scarce ; some arc very constant in their coloration, others 

 vary so much that it is diflicult to hud two specimens 

 exactly alike. In some species the spots are black on a red 

 or yellow ground, in others cream-coloured or yellow on a 

 black or dark red ground. The spots may be either round 

 or angular ; they are generally simple, but in one or two 

 instances are surrounded by a ring of another colour. 

 Finally, on(^ species has no spots at all, but a distinct black 

 M-like mark on the thorax. The spots vary in number in 

 the difl'erent species, but are, as a rule, remarkably constant 

 in difl'erent specimens of the same species. Tlius th«ro are 

 species with li, 5, 7, 11, 12, 13, U, IC, 18, 19, and 2ii 

 spots respectively, that is, reckoning only those that adorn 



the wing cases. The commonest of all is that which has 

 two spots, one on each wing-case ; its usual coloration is 

 black spots on a red ground, but sometimes the black 

 spreads so as to almost entirely cover the back, leaving 

 only two shoulder-spots of red, and the insect then looks so 

 difl'erent that it is diflicult to believe that it is the same 

 species. Some species, the most handsome of the group, 

 are specially addicted to fir-trees ; others occur in damp 

 places, and some few, such as the two and seven-spotted 

 forms, may turn up anywhere. 



CAYEENS IK EARTH AND MOON. 



By Richard A. Proctor. 



AS I find few points in my views about the future of 

 the Earth-World received with more difficulty than 

 my statement that the waters of the sea, if they should 

 eventually retreat into the earth's interior, as Sir Isaac 

 Newton suggested, could certainly never retreat into cavi- 

 ties — seeing that " such cavities could no more exist in the 

 solid frame of the earth than within the mass of an ocean," 

 I take ))leasure in quoting some remarks by Mr. W. 

 Mattieu Williams, bearing very pertinently on this matter, — 

 as well as some remarks relating to limestone caverns, 

 showing one of the ways in which waters once above the 

 earth find their way below its surface. It will be inferred 

 from Mr. Williams's words that some persons, presumably 

 Oxonians or Cantabs, have recently been advocating the 

 preposterous theory of which he so eS'ectually disposes. 

 And although it may seem to many that the theory re- 

 quires no answer, being inherently too absurd for belief, 1 

 know from experience that the case is otherwise. Many 

 who have spoken to me after my lecture on the " Life of 

 Worlds " have shown that they still retain a vague han- 

 kering for this impossible view, which associates itself con- 

 veniently with Sir David Brewster's explanation of the 

 small density of the external planets. 



I may add that the capacity of some persons for starting 

 ofl' with a full and complete idea — as they suppose — of a 

 special theory, from perhaps a casual and blundering 

 remark about it in some news)iapcr paragraph, would be 

 regarded by many as absolutely incredible. 



It will be observed that Mr. Williams in touching on the 

 theories which he himself advanced in his ingenious, though 

 rather crude, " Fuel of the Sun" speaks of them with great 

 confidence, — a tone not usually sustained as advancing 

 study teaches the limited nature of our knowledge, and 

 the utter impossibility of forming any widely extending 

 theory (especially a theory of the universe). That however 

 need not prevent the reader from accepting the grains of 

 real information conveyed in what follows. The " perpe- 

 tual motion " theory, which underlies what Mr. Williams 

 suggests as to the unvarying condition of the several 

 orders of bodies in the universe, seems, oddly enough, 

 acceptable, on a very large scale, to those who would 

 laugh at it if advanced in regard to mechanism on 

 some more appreciable scale, — who might even invite 

 the inventor of the mechanism, as Robert Stephenson 

 did in such a case, to cairy himself round the 

 room by the waistband of liis own trousers and tht-n 

 explain his perpetual motion. Mr. Williams's wider per- 

 petual motion (really but a much magnified mistake) might 

 lead rud(^ persons to suggest a more heroic achievement, — 

 he might be asked to convey himself by the atore-mentioned 

 waistband on a lecture tour round the world and then try 

 to establish the perpetual mechanism of suns and sun 

 systems, and (as an additional trifle) the amazingly ini- 



