HARD WICKE 'S S CI EN CE-GO SSIF. 



229 



circulate in the system of the insect. It may also 

 undergo a chemical change, but as to this, it is not 

 easy to decide. 



A further question arises : — What becomes of the 

 body of the insect imbedded in tlie skin ? Is it, after 

 decomposition, absorbed by the blood, or is it ex- 

 pelled by perspiration from the pores of the skin? 

 We are inclined to think that the latter is the case. 

 A still further question arises :— What is the best 

 fluid to apply to the skin to allay irritation ? Speak- 

 ing from experience, we say, moderately strong 

 acetic acid or concentrated common vinegar. Our 

 knowledge of chemistry also points to this, acetic 

 acid being a solvent of animal substances. 



Finally, we may remark that the reproduction of 

 species with this insect appears to be by the deposition 

 of ova on the under parts of leaves, and underneath 

 the bark of small garden trees and shrubs. The 

 harvest-bug is believed to live one season only, as a 

 rule, but we have found it in a dormant state in 

 winter underneath the decaying bark of the garden 

 currant-tree. We failed, however, to ascertain as a 

 fact that it again became active in the succeeding 

 summer or autumn. 



In this, as in all the works of the Creator, we see 

 infinite design ; but the exact part this little creature 

 is designed to fulfil in the economy of nature is as yet 

 a mystery to man. 



I should remark that my sketch is from a very fine 



specimen. 



J. E. Stephens. 



Inland Revemce, Alloa, N.B. 



THE METAMORPHOSIS OF THE WHITE 

 CABBAGE BUTTERFLY. 



(Pier is brassica.) 



ON seeing the curious manner in which the 

 chrysalis of the butterfly is suspended by a 

 silken cord round its body, one would naturally ask 

 how this was accomplished. There is something so 

 wonderful that a creature like the 

 caterpillar should spin a thread of 

 silk, and so utilize it as to hang itself 

 up by it in a position suitable for the 

 future development of the butterfly, 

 that I do not think it a waste of time 

 or labour in attempting to explain the 

 way it is accomplished : this I have 

 endeavoured to do by the aid of the 

 accompanying sketches. I procured 

 a number of caterpillars and kept them 

 until they were full-fed, when they leave their food and 

 travel in search of a spot suited for them to undergo 

 their metamorphosis. In this case, being kept in a 

 glass box, they had to travel up the smooth glass. 

 This they easily accomplished by spinning a ladder of 

 silk in a zig-zag form. Having fixed themselves to a 



spot, they then rested quiet for some time, hanging 

 in the position of fig. 175. When about to commence 

 forming the silk cord that is to support the future 

 chrysalis, they do so by bending the head backward 

 to about the fourth segment of the body (fig. 176), and 

 then turning the head downwards on the right side, 

 so as to bring the mouth to the points, fig. 176. The 

 caterpillar there fixes the first line of silk, and then 

 carries the head over to the left side, spinning a line 

 of silk at the time, and fastening it down on the left 

 side ; again bringing a line of silk back over to the 

 right side, and fastening it down. This process is 

 continued and repeated until about forty lines of silk 

 are in this manner drawn across the body and the 

 head. At this time the silk is drawn so tight that, 

 to appearance, the head of the creature is in danger 



Fig. 175. Stage of metamorphosis Fig. 177. Chrysalis of 

 of P. I'rassictF. P. brassictr. 



Fig. 176. Another stage in ditto. 



of being severed from the body ; but this does not 

 happen, as the caterpillar is very soft and flexible, 

 and will bear a large amount of pressure. Now 

 comes the task of releasing the head from this bent- 

 back and tied-down portion. I confess that I watched 

 this movement with a degree of curiosity, and was 



