l6 Proceedings of the 



is alive and fresh from the pupa-case. These sacs are afterwards flattened 

 dovm and lost to sight. Every now and then the growth-fluid is suspended, 

 whilst colour or strengthening power is driven forward ; but just before 

 the wings attain their full size, a sudden flush of pigment, dilute in character, 

 is forced through the nerves and into the scales themselves, which after- 

 wards receive the last of the strengthening fluid (used chiefly in the 

 secondary cilia of the wings) ; this also gives an individuality to the 

 scaling, and thereby possibly increases buoyancy. By this time the wings, 

 having obtained their full development, are thrown over the back ; the 

 surplus fluid is absorbed or returned to the body, rendering the colouring 

 less vivid ; and the arteries and veins consolidate. After a little time the 

 insect tries its wing muscles, and then again reposes for a time, often in a 

 different position. The times of day andnight for emergence vary considerably. 

 Sometimes an imago seems to make no progress in its development; 

 this is quite as often due to an excess as to want of power ; a gentle 

 touch, so as to make it change its position and extrude moisture, will 

 generally facilitate matters. Insects bred as cripples or with imperfections 

 should never be retained for breeding purposes ; for defects, whether of 

 form or colour, whether as three-winged, notched in the cilia, or with 

 twisted antennae or tibia, are distinctly stated by various authors to be 

 congenital. Varieties, too, will beget varieties, and transmit iheir peculi- 

 arities unchanged to their offspring, so that it would appear to be in the 

 blood to use a common and colloquial expression, and, this being so, the 

 elaborate theories of variation are reduced to a simpler code, though the 

 primary causes are still distant and but little understood. Fortunately 

 my subject does not require me to go deeply into this matter, but I must 

 shortly consider how far differences of atmosphere and light may tend at 

 the time of extrusion to develop aberrations. Firstlj^ we may take it as 

 a fair axiom that great heat develops colour brightness among the blues, 

 reds or yellows. This may often be seen in insects of a second brood. 

 The o-enus Ephyra is a good example. Next, that damp (unless this happens 

 to be extreme) during the pupal condition does not effect the imago, ex- 

 cepting in the case of a sun bleach, which is most usually seen in the 

 Diurni. I have made many experiments on sun-bleaching, but without, at 

 present, arriving at any definite results. Thirdly, it has been suggested 

 that varieties are caused by and owing to a supercharged electric atmo- 

 sphere. This might be tested by allowing a number of larvae to pupate 

 below the soil of a breeding-cage, and by means of a battery passing 

 currents constantly through the earth about the period of emergence. Of 

 conjecturally altered specimens by this means, Mr. Bond has Pamphilus, 

 a variety of which he attributes to some such cause ; and 1 exhibit Janira 

 bred by myself this year, the first of which was hatched out and developed 

 durinc a violent thunderstorm on the morning of the '26th June ; the 

 second, which is not so strongly marked, appeared on the 28th, thunder in the , /^ 

 ■distance with lightning all night ; but other species coming out at the same 

 time in a normal condition, I attach little importance to the matter ; but 



