SELECTION 163 



Mantis,' Mantis religiosa, occurs in Italy 

 in a green and a brown form. The former is 

 usually to be found on green grass, the latter 

 on herbage browned by the sun. Mr. Cesnola 

 tied down among green herbage twenty green 

 Mantis, and among withered grass a similar 

 number of brown individuals. After seven- 

 teen days they were all alive. He also 

 tethered twenty-five green Mantis among 

 brown herbage, and they were all dead after 

 eleven days. The converse experiment was 

 also made, forty-five brown Mantis being 

 exposed on green grass, and of these only ten 

 survived at the end of seventeen days. Most 

 of the Mantis were killed by birds ; five of the 

 green ones were killed by ants. Here, then, 

 is a proof, quite conclusive though the num- 

 bers are small, of the selective value of the 

 protective colouration of both races of 

 Mantis. If green Mantis and brown Mantis 

 be exposed on green grass, the green ones 

 will survive rather than the brown, the 

 death-rate will be selective. Such a simple 

 experiment gives more solid support to the 

 view that protective colouration is due to 

 natural selection than any accumulation of 

 probabilities. ' 



It is of enormous importance that cases 

 similar to the above should be accumulated, 

 so that stability may be given to the theory 



