SHELLS V. INSECTS. 171 



the stomach of these three fish. No. 1 con- 

 tained a great quantity of small water-shells, 

 and nothing else whatever. No. 2 contained 

 not a single shell, but a quantity of insects, 

 principally winged black ants, midges, and 

 those peculiar black flies who seemed to de- 

 light in committing suicide in the eyes of 

 human beings. The stomach of No. 3 con- 

 tained nothing, or positively next to nothing; 

 anyhow I could not make out what it was. 

 A lawyer arguing the case might take this 

 difference in food as evidence of the cause of 

 the difference of the growth of these fish. 

 Anyhow, dissection proves the fact, that the 

 food is different as regards fish Nos. 1 and 2 ; 

 and this, combined with the arguments above 

 stated, will, I think, enable us to agree that 

 the cause of the phenomenon sent by ' Peter 



