28 
treme cases the lower part of red patch appears almost obliterated” 
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 pear! 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 them 
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 an 
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 spring 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 scme of her workings—has given us a peep into her 
laboratory, so to speak; and it is reasonable 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 wilk 
set themselves the task of putting that and that together, and we- 
shall reach a far higher standard of knowledge, not only concern- 
ing the variation of butterflies and moths, but of other creatures. 
which constitute the animated world, whose variability is stilk 
wrapt in considerable mystery 
After the lecture, Dr. Knaggs pointed out the wonders and 
