INTRODUCTORY. 



11 



have no hesitation about accepting the facts 

 recorded. There is another feature in this 

 periodical moulting equally interesting, and 

 that is that the spines, hairs, warts, and other 

 appendages of the skin, so conspicuous in 

 many of the caterpillars, are shed with the 

 skin, and, we learn from the same high autho- 

 rity, are replaced by similar ones which existed 

 and have been perfected beneath the skin that 

 has been cast, although of necessity bent down 

 an<l flattened between the new and old cuticles. 

 The observations of Swammerdam are con- 

 firmed by precisely similar ones recorded by 

 B iimet, but have been called in question in 

 M)ine of their details by Herold ; still these 

 objections have only been raised in respect of 

 the moulting of some of the minor air-vessels. 

 No doubt has been expressed as regards the 

 larger air-vessels commonly known as trachese. 



After this formidable operation of moulting 

 is accomplished, the body is excessively soft 

 and tender; the head, after wards so hard, and 

 the legs afterwards so horny and so sharp- 

 pointed, are as pliable and yielding as the 

 most delicate skin, and are covered with a 

 transparent gummy fluid, which was pre- 

 viously confined between the new skin and 

 the old : as the creature now lies exhausted 

 by the exertion, the fluid gradually evaporates, 

 and the new skin gradually acquires the hard- 

 ness and dryness of the old one : and when 

 the caterpillar has thoroughly recovered its 

 former state, its appetite seems to return, and 

 its voracity to be redoubled, as if to make 

 amends for its lengthened abstinence. Its 

 colours, which on first emergence were dull 

 and faint, become vivid and distinct, and its 

 whole appearance is altered and improved by 

 the ordeal through which it has passed. 



The caterpillars of butterflies are extremely 

 fastidious about their food, in this respect 

 differing very essentially from other leaf-eating 

 creatures. We know that horses, cows, sheep, 

 and pigs will eat with apparent relish almost 

 any foliage that is offered them, and birds in 

 a cage seem glad of every green leaf. With 

 caterpillars it is otherwise ; they uniformly 

 refuse almost everything except the leaves of 

 Uutt particular species of tree, shrub, or herb 



on which the parent had laid its egg. It is 

 very interesting to observe the wonderfully 

 perfect power of discrimination which they 

 exhibit, a power that seems vested in twelve 

 minute microscopic eyes, seated six on each 

 cheek, almost close to the mouth : these eyes 

 are highly convex lenses: strikingly reminding 

 one of a Coddington lens : such is the extreme 

 convexity of these eyes, that it is impossible 

 for them to convey an idea of any object to 

 the insect using them unless they are brought 

 into contact, or nearly so; consequently, the 

 caterpillar seems to examine with bis mouth 

 the surface of each leaf before he ventures to 

 nibble. If you take a caterpillar from oak 

 and put it on hawthorn, it will maunder about 

 in hopeless helplessness ; and if you change 

 one from hazel to birch, the same effect will 

 be produced : the position of these microscopic 

 eyes is admirably adapted for the purpose they 

 serve : they are only capable of discerning an 

 object immediately below them. How differ- 

 ent is this from the conduct of the parent 

 butterfly, which selects even from a distance 

 the leaf designed by Nature to serve as food 

 for her offspring. 



The caterpillars of butterflies are composed 

 of thirteen rings or joints, which entomolo- 

 gists call segments. 



The first segment is the head, and is fur- 

 nished with two short antennae, two feelers, 

 two jaws, and the twelve minute microscopic 

 eyes to which I have already alluded. 



The second has two spiracles or breathing 

 holes, one on each side, and two jointed legs. 



The third has two jointed legs only. 



The fourth has two jointed legs only. 



The fifth has two spiracles only. 



The sixth has two spiracles only. 



The seventh, eighth, ninth, and tenth, have 

 each two claspers and two spiracles. 



The eleventh and twelfth have each two 

 spiracles only. 



The thirteenth has two claspers only. 



It is almost useless to say anything about 

 the use or objects of the ANTENNA, after all 

 that has been written ; but it is the general 

 fault of all scientific men who have written 

 ou the subject to assume that they must bs 



