liv 



wasp alone secretes a non-acid poison. This fact surely merits further 

 examination. 



" Turning to structural peculiarities among insects, we find facts less 

 favourahle to the views of Dr. Beale and to the anti-evolutionist inferences 

 whicli he evidently draws. Thus, M. J. Kiinckel, in his lately published 

 researches on the nervous system of the Diptera declares that each family 

 of that order has its nervous system constructed upon a pecuHar and 

 invariable plan, and that the number of nervous centres varies gradually 

 from one family to another. M. E. Brandt also shows that whilst the 

 convolutions of the so-called 'pedunculated bodies of Dujardin' vary in their 

 development in different species, yet that such variations occur also among 

 different individuals of the same species. No one can doubt, for instance, 

 the common descent of the working bee, the queen, and the drone, yet in 

 the last-mentioned insect these convolutions are much simpler than in the 

 former. 



" Being, however, desirous of investigating Dr. Be.de s supposition 

 further, I thought it might be useful to make a comparative examination, 

 in a number of species, ef some parts not liable to be modified by adaptive 

 influences. It may seem strange that I should have selected for this 

 purpose parts which have been so often and so unsuccessfully examined as 

 the wing-scales of Lepidoptera. I proceeded, however, in a manner which 

 has probably not been getieral. From each of the seventy-one species 

 which I examined I took, as a rule, six portions of scales from determinate 

 regions of the wings — viz., from the centre of the fore wings, from the 

 middles of the anterior and exterior margins of the fore wings ; from the 

 middle of the posterior margin of the hind wing, from near its root, and 

 from the middle of the hind wing underneath. Special portions were also 

 taken from eye-spots, wherever situate, from the wing-tails of FiqnUonida:, 

 or from other parts where a structural peculiarity might be expected. For 

 convenience sake all these portions were put up as dry slides, and 

 submitted to a comparative examination with a microscope. 



" I may say that I found none of those exceptional differences between 

 any one species and other species in the same genus which would be 

 required to serve as an argument against evolution. The differences between 

 the scales from two distinct species are often less striking than those from 

 the two sexes of one species or from different parts of one individual. 



" Whilst the apices of the scales vary to an almost endless extent, and 

 in a manner in which I have hitherto failed to trace any definite principle, 

 there is great regularity in the insertion of the stem of the footstalk. This 

 is either attached to a rounded or pointed extremity of the scale like the 

 stalk of an ordinary leaf, or it is inserted between two projecting lobes or 

 angular appendages which may vary considerably in shape and proportion. 

 The latter style of insertion is found in all the diurnal Lepidoptera which 



