The Tachytes 



consider its supreme .talent as an anatomist. 

 Many a time I have insisted upon the incom- 

 prehensible wisdom of instinct; I do so again 

 at the risk of repeating myself. An idea 

 is like a nail: it is not to be driven in save 

 by repeated blows. By hitting It again and 

 again, I hope to make it enter the most re- 

 bellious brains. This time I shall attack 

 the problem from the other end, that is, I 

 shall first allow human knowledge to have 

 its say and shall then Interrogate the insect's 

 knowledge. 



The outward structure of the Praying 

 Mantis would of itself be enough to teach 

 us the arrangement of the nerve-centres 

 which the Tachytes has to injure in order to 

 paralyse its victim, which is destined to be 

 devoured alive but harmless. A narrow and 

 very long prothorax divides the front pair 

 of legs from the two hinder pairs. There 

 must therefore be an isolated ganglion in 

 front and two ganglia, close to each other, 

 about two-fifths of an inch back. Dissec- 

 tion confirms this forecast completely. It 

 shows us three fairly bulky thoracic ganglia, 

 arranged in the same manner as the legs. 

 The first which actuates the fore-legs, is 

 placed opposite their roots. It is the largest 

 of the three. It is also the most important, 



