THE NEW ENTOMOLOGY. 113 



r " Thus has the evolutionary idea of life been assailed, and more 

 especially with Entomological arms. For instance, although we 

 may cite mimicry as a most cogent evidence of modification of 

 form or colour by the pressure of the environment, and indeed 

 believe that there can be no other tenable theory to explain its 

 manifestation ; yet when we come to consider the method of 

 change, step by step, we feel almost crushed by a sense of the 

 impossibility of a rational explanation of the modus operandi. 

 A Pieris could only obtain protection by its resemblance to a 

 Heliconia when that resemblance had become approximately 

 perfected; but what started the development along that particular 

 line, and what carried it on '? We must necessarily believe the 

 change to have been very gradual, a few scales at a time, and in 

 many generations. How was it then, if the species needed that 

 protection for its very existence, that it was not exterminated 

 before it had time to arrive at that pitch of resemblance which 

 alone could afford the necessary protection ? You perceive the 

 difficulty, and this is only one of a thousand which the entomo- 

 logist can ask. 



Thus most of my readers will be aware that the pages of one 

 of the "serious" reviews have lately been the arena for an 

 encounter of the greatest interest and moment between two of 

 the most eminent of living Biologists. I refer to Mr. Herbert 

 Spencer and Professor Weismann. Their weapons are taken 

 almost exclusively from the entomological armoury ; and the 

 Sphinx-like riddle on which the Englishman attempts to impale 

 his adversary is something like this. 



If, as you contend, all specialized forms are the result of the 

 pressure of the environment acting through heredity, and fur- 

 ther, if acquired variations are not transmitted, how do you 

 explain the very specialized forms of worker ants and bees ? For 

 not only is each species clearly differentiated from the rest, 

 but these workers, so differentiated, are themselves structurally 

 distinct from the males and fertile females of the same species. 

 Yet the workers or neuters, being sterile, cannot transmit bene- 

 ficial variation, and the environment which justifies such 

 variation in the workers has no application to the males and 

 perfect females which do transmit. 



The difficulty is not a new one, but the question is one of the 

 many which are much easier to ask than to answer. How the 

 German Professor replies, and how his opponent rejoins, and 

 what are the arguments they employ, with these I will not further 

 weary you, for whoso will may read them in the pages of the 

 * Contemporary.' I have indeed only referred to all this to 

 demonstrate how Entomology is not now merely the innocent 

 hobby of a few mild enthusiasts, but has become the necessary 

 equipment of the modern scientific Biologist. 



Perhaps I ought to add, as a further department of the new 



