Makch 1, 1898.] 



KNOWLEDGE 



43 



^^Z ± t'^^'r fifth stage, a great change comes over 

 hem. The castmg of the skin on this occasion leaves 



them not green as heretofore, but with a coat of brown 

 ns ead ; this at least is what happens to the majority, 



though some few erratic individuals still retain the]; 



juvenile greeiiness, which, indeed, they never lose. Con- 



nf'T.S ""f '^'' '"'^"S'^ ^" '°^^''' ^^^'^ i« ^^ alteration 

 tut7lf\u fT": °° ^o'^ger rest amongst the fresh 

 fol age of the food plant, but descend to the ground when 



onlfl ^^' J^'''' ^^''' ^^^^^^'^ ''"l""^- i« as efficacious in 

 concealing them amongst the dead leaves, stems, and 

 b own soil, as it would have been in exposing them had 

 they remained embosomed in green. 



But this is not the only peculiarity. When first hatched 

 ISL 7 ^''° T'^'/^Ss of any kind, but after the first 

 change of skin, which takes place when they are five or six 

 clays old, they appear with two longitudinal white lines 

 stretchmg he whole length of the body. At this time 

 they are utterly unlike what they will ultimately become. 

 Alter a few days, the upper line, in the region of the 

 ientr-'^ ^^'\ segments behind the head, begins to show 

 signs of irregularity, a slight swelling appealing in each 

 of these segments These are the commencements of the 

 eye-spots, though from their present appearance it would 

 be quite impossible to predict what they might become- 

 indeed they are most_ inconspicuous, and only to be noticed 

 at all by a care ill mspection. By another moult they 

 pass into their third stage, when it is observed that the 

 ower line has disappeared, and the two white swellings 



W, aT If^""' r"^"''? now recognizable as distinct 

 spots. After thenext moult, the most noticeable change 

 IS that the mcipient eye-spots are larger and are now 

 suiTomaded by a b ack line. Again in the next stage, thi 

 fifth and last but one, the spots are much largfr the 

 black margins being spread out into a broad patch, and 

 he wh, e reduced to a ring by the appearance of a Violet 

 spot n Its centre so that it now begms to look something 

 like an eye. At the same time, the longitudinal lines 

 become almost obliterated and ,Ua,on„l ones take Jheir 

 place. In the final stage all these points are still more 

 emphasized and at the same time, the third and fourth 

 segments, which at first were no larger than the rest, have 

 become considerably swollen, while the head look diL 

 proportionately small, having grown hardly so much as 

 might have been expected. Hence the caterpillar suddenly 

 bulges ou in the third and fourth segments, and this 

 becomes all the more marked when the head is dkwn back 

 I^IV'^T'^'''' ^' eye-spots on the fourth segment are 

 brought into great prominence, and the whole of the 



!nl ■ V, ^^ '"'.f' ^""l""'^' ^ ^^'Sht resemblance to a 

 ZtMt \ ^'^^ f ^"v^- ''°°y 'y^'- Tbe effect, even 

 upon those who are familiar with the msect, is really quite 

 s artlmg, and it is chfficult to persuade oneself that those 

 glaring orbs are not really eyes with the most cruel and 

 penetratmg glance. 



Now these eye-spots are unquestionably of considerable 

 use to the msect ; for, suggesting as they do a Cgerous 

 animal which i will be as well not to molest, they^ warn 

 off any but the hungriest or most knowing of enemies and 

 save their possessor's life. And well the poor c eatm-e 

 needs such a defence, for it appears to bf a dec d d y 

 palatable morsel to insectivorous vertebrates. There is 

 direct evidence, too, that the above suggestion of the function 

 ot tne eyespots is not mere imagination. Dr Weismann 

 who has made a particular suidy of th cZr and 

 rnarkingsof the Sphin.id. in general, was especially Tn 

 terested in this species. He had an enclosure for 12 

 which was. open above, so that wild birds could easily fiy 

 m, and this they were often accustomed to do whenever 



the fowls were not there. On one occasion Weismann put 

 a large brown larva of the elephant moth in the food 

 trough, alter having removed the fowls. Flocks of 

 sparrows and chaffinches soon flew down as usual,'and 

 alighted near the trough in the hope of picking up gram 

 or other .stray food. One bird soon flew on to the edge of 

 the trough and was about to hop into it, when it caught 

 sight of the caterpillar. This deterred it, and it stood 

 jerking its head enquiringly from side to side, but did not 

 venture to go any nearer. One after another, about a 

 dozen of the birds acted m the same way ; when, however 

 the caterpillar was removed, they hopped into the trou<rh' 

 briskly enough The fowls themselves behaved somewhlit 

 similarly. When a specimen was placed in their midst, 

 they at first ran hastily towards it, evidently in expectation 

 ot a feast, but as soon as they came near to"it, they stopped 

 and ran round it irresolutely, and it was not till after 

 somethmg like a score of half-hearted attempts to seize it 

 in each of which courage had failed at the last moment, 

 that one more courageous than the rest at last reached the 

 msect, and finding that nothmg serious happened, pecked 

 away at it till it was demolished. Caterpillars of ordinary 

 appearance were, of course, swallowed at once without any 

 difficulty A domesticated jay was much more plucky 

 and swallowed the elephant caterpillar as soon as it was 

 ottered ; but as domestication has the effect of takinc. off 

 much of the shyness of birds in other respects, il is 

 possible that this boldness may have had a similar origin, 

 and that the bird would not have acted thus in the wild 

 state. 



We have not space to pursue this subject further, but 

 can only indicate the general conclusions which seem to 

 loilow from the experiments and observations mentioned 

 in this paper. These are, that the colours and patterns of 

 caterpillars are not accidental, but have an intimate 

 relation to their circumstances; that they can, at least in 

 some cases, be modified by their environment, and that 

 many have thus become useful to their possessors, whereby 

 again they tend to be perpetuated ; and finally, that the 

 order m which the changes of colour and pattern appear in 

 the life of the individual specimen is also that in which 

 they have been acquired in the life of the species, so that 

 the progressive changes observable in the present-day 

 caterpillar s individual experience reveal somethino- of the 

 facts which constitute the past history of the generations 

 which have preceded it. 



DEEP SEA DEPOSITS. 



By Kev. H. N. Hutchinson, B.A., F.G.S., Author of 



" Extinct Monsters." 



[First Paper.] 



THE wish to know something of what goes ou " at 

 the bottom of the deep blue sea " is a very natural 

 one, but until late years the bed of the ocean has 

 been a terra incoi/nita. Popular imagination, how- 

 ever, fastens itself more on the sunken treasures 

 a,nd dead men's bones than on the natural phenomena and 

 lile of the deep sea. We propose, however, to consider 

 only the scientific aspects of the subject, and to endeavour 

 to lay before the reader a brief account of the deposits now 

 in process of formation ou the bed of the sea. Eecent 

 deep sea dredging expeditions have opened out a new world 

 to the naturalist, the geologist, aud the geographer Of 

 this new world we will endeavour to give a few glimpses 

 though the light at present thrown on it is only as moon- 

 light to sunlight. Within the last thirty or forty years 

 many ships belonging to different nations have, by means 



