00 J. W. SLATER, ESQ., F.C.S., F.E.S., ON 



why are many insects, known to be venomous or offensive, 

 clad with remarkably gay colours. Mr. Wallace and my late 

 friend Thomas Belt held that these colours are a danger- 

 signal, and have observed that such creatures are in fact 

 shunned. I have found that some of the most strikingly 

 coloured caterpillars feed on deadly plants and retain poison- 

 ous principles in their bodies. Yet Mr. Grant Allen, on the 

 other hand, does not believe in warning colours, but asserts 

 that poisonous plants, such as the arum, have, by a process of 

 Natural (Selection, developed intensely brilliant colours so as 

 to allure birds to eat them. The seeds are then supposed to 

 vegetate more luxuriantly in the decaying body of the 

 poisoned bird. I cannot learn that Mr. Allen has ever met 

 with a dead bird with arum-berries in its crop. 



It would surely be a boon to the scientific world if the 

 leading Darwinians would come to some understanding con- 

 cerning natural selection and tell us what we are expected 

 to believe. 



But I must now ask if this process can produce new 

 species? It has been admitted that before natural selection 

 can come into play, variation must have already set in. 

 Suppose a pair of animals existing in the primeval world 

 had produced a hundred fertile ova. There are then only 

 two possible cases: the young animals springing from these 

 ova must either be one and all exactly alike, or they must 

 exhibit certain differences. In the former alternative there 

 is absolutely no ground for natural selection to work upon ; 

 the very idea of selection implying differences in the objects 

 among which a selection is to be made. In the second alter- 

 native the varieties being, by hypothesis, antecedent to the 

 action of natural selection, cannot be its effects. Hence in 

 either case we have something which the Darwinian theory 

 is quite unable to account for. We want a law which shall 

 go deeper than Natural Selection, before we can understand 

 the origin of species. At present we are merely offered, as it 

 were, a rope ladder with no point from which it may be sus- 

 pended. 



We may ask how can Natural Selection have developed in 

 any animal a power far beyond its utmost need? There is a 

 small black spider in Southern Russia, that lurks among grass. 

 Horses and cattle are often bitten upon the lips whilst 

 grazing, and sometimes die in consequence. How can such 

 a poison have been developed? What benefit can it confer 

 upon the spider ? It is, of course, unable to eat the dead 



