( xlvii ) 



aud transplanting the larva from one to the other, and vice versa, 

 and at various points, in the above-mentioned period, before 

 pupation. If the transplantation took place a short time before 

 the larval skin was thrown off, the pupal colour corresponded with 

 the previous surroundings in which a far longer time had been 

 spent. In this way it was found that the pupse are affected, to 

 some extent, by the colour of their surroundings duriug the time 

 when the larvae are suspended, head downwards, for mauy hours 

 before pupation, although to a much greater extent if the same 

 surroundings were also present during the quiescent state before 

 suspension. Still the fact was very important, because the 

 suspended larva might be subjected to experiments which could 

 not be tried upon the free, although passive, larva. The first and 

 obvious theory, as to the larval organs which were affected by the 

 colour, was that the ocelli performed this function, but no difference 

 was caused when these were covered carefully with a thick layer of 

 opaque varnish which, if necessary, was renewed. It was then thought 

 that the large aud complex spines might contain a terminal organ 

 with such a function, but no effect was produced when they were 

 snipped off. Then the frame, exhibited to the Society, was devised 

 with the object of deciding whether the influence makes itself felt 

 through some organ in the head, or by the general surface of the 

 body. The frame consisted of a shallow box, divided into 

 parallel areas of equal size, which were alternately gilt and 

 covered with black paper. Along the lines of junction of the 

 areas, which extended actoss the box, cardboard shelves were 

 fixed, which were in each case gilt on the side towards the gilt 

 area, and black towards that which was black. The shelves were 

 perforated with holes, pierced at equal distances, close to the gilt 

 aud black surfaces of the box, the holes being of such a size that 

 the larva of V. urtictn would pass through easily, but leaving as 

 small a space as possible between the latter and the sides of the 

 aperture. As soon as suspension had taken place the boss of silk, 

 with the larva attached, was carefully removed and pinned on to 

 one of the areas, in such a position that the head and thoracic 

 segments could be pulled through one of the holes in the shelf 

 which separated the area from the one below it. Hence nearly 

 the whole of the body of the larva was exposed to one condition, 

 and its head and anterior part to an opposite condition. When 

 the frame was filled (t. e., when a suspended larva passed through 



