treme cases the lower part of red patch appears almost obliteratecP' 

 with black scales. Blue scales appear between white patch and- 

 band, and sometimes on the other side, and hind end, of red band. 



I now come to a very interesting continental creature. It 

 belongs to the same group as those to which we have just referred^ 

 but it is double brooded, and the two broods are about as unlike- 

 one another as can possibly be imagined ; the summer brood is 

 brown-black, with a bold cream coloured interrupted band running- 

 through both wings, reminding us of our white admiral. The- 

 spring brood, however, is tawny orange, with innumerable small 

 dark brown markings, reminding us of oar pearl bordered fritillary ; 

 these in nature succeed each other ; by art, we can alter nature's 

 arrangements, and make the chrysalis which ought to yield the- 

 spring brood, produce the summer one. Nay, more, we can alter 

 the size and shape of the spring into the summer form, and thert 

 put on the spring colour. 



The next sketch illustrates the two broods of the purple thorr.^ 

 the spring being the upper figure. It will be observed that the • 

 outer edge of the dark inner portions joins the front margin at aa 

 acute angle. This is one of the effects of cold ; so to is the angu- 

 lation on the corresponding edge of dark mark in the lower wing, , 

 as also the production of the tip, giving it a scalloped appearance ; 

 the lower, summer brood, you will notice differs considerably in 

 these particulars ; by art we can breed from the eggs of the summer 

 form either the summer or spring form, and " vice versa, " at our 

 will. But, having produced the spnng form, we cannot reinstate 

 the summer shape or markings, though we can alter the dark spring 

 markings into the warmer red hue of the summer brood. Among 

 Mr. Webb's selection will be found an instance of this — this may 

 occur in nature, in art it is effected by first administering a month 

 of cold, then two days at 99deg. F., afterwards the temperature of 

 an ordinary room, say 70deg. F. 



From the foregoing it will be seen that this method of investi- 

 gating the secrets of nature, though yet in its infancy, has even 

 now disclosed seme of her workings — has given us a peep into her 

 laboratory, so to speak ; and it is reasoxiable to anticipate, from 

 the startling results already obtained, that when the number of 

 careful observers and diligent students is multiplied, and they get 

 to work to accumulate a further supply of facts, our scientists will 

 set themselves the task of putting that and that together, and we • 

 shall reach a fnr higher standard of knowledge, not only concern- 

 ing the variation of butterflies and moths, but of other creatures 

 which constitute the animated world, whose variabihty is still 

 ■wrapt in considerable mystery 



After the lecture. Dr. Knaggs pointed out the wonders and^. 



