390 Darwin, and after Darwin. 
because it is the one which has been published most 
recently, and partly because it is of particular interest 
as occurring so low down in the zoological scale. I 
am indebted to the kindness of Mr. and Mrs. Peckham 
for permission to reproduce these few selected drawings 
from their very admirable work, which is published by 
the Natural History Society of Wisconsin, U.S. It is 
evident at a glance that all these elaborate, and to our 
eyes ludicrous, performances are more suggestive of 
incitation than of any other imaginable purpose. And 
this view of the matter is strongly corroborated by 
the fact that it is the most brightly coloured parts of 
the male spiders which are most obtruded upon the 
notice of the female by these peculiar attitudes--in 
just the same way as is invariably the case in the 
analogous phenomena of courtship among birds, 
insects, &c. 
But so great is the mass of material which Darwin 
has collected in proof of all the points mentioned in 
the foregoing paragraph, that to attempt anything 
in the way of an epitome would really be to damage 
its evidential force. Therefore I deem it best simply 
to refer to it as it stands in his Descent of Man, 
concluding, as he concludes,—* This surprising uni- 
formity in the laws regulating the differences between 
the sexes in so many and such widely separated 
classes is intelligible if we admit the action throughout 
all the higher divisions of the animal kingdom of one 
common cause, namely, sexual selection” ; while, as 
he might well have added, it is difficult to imagine 
that all the large classes of facts which an admission of 
this common cause serves to explain, can ever admit 
of being rendered intelligible by any other theory. 
