Pouiton.j 392 L^^ay '6. 
experience. Certain ITynienoptera allied to wasps possess an 
instinct which leads them to sting larvae and store them up in 
their nests as food for their young. It is generally believed that 
the larva is stung in the central part of the nervous system so 
that it can no longer struggle. I say "generally believed" 
because it has been pointed out to me by so distinguished an 
observer as Dr. Peckham of Milwaukee, that certain facts are 
opposed to the generally received account. It is to be hoped 
that the observations which are chiefly due to Fabre will be 
repeated and tested as minutel}^ as possible. The prey is stored 
up in the mud-tube or burrow of the hymenopteron, and keeps 
perfectly fresh because it is alive, although completely paralyzed. 
Larvae stored iip in this way appear to live much longer than 
those which, in the full possession of their faculties, are deprived 
of food. 
Now this is a very wonderful instinct, and it has been argued 
that here is a case which cannot be explained except on 
Lamarckian lines, I maintain, on the contrary, that it is a case 
which cannot by any possibility be explained on Lamarckian 
lines. 
The wasp-like insect has no opportunity of learning by experience 
because it can never know whether the larva stored up is a failure 
or a success. If the larva had not been stung, or, accepting the 
received accounts, had been stung in the wrong place, it would 
struggle and perhaps kill the young grub ; or dying of starvation 
it might dry up and be useless as food. But the hymenopteron 
never goes back to inquire. It makes all the difference to the 
young grubs whetlier the food provided for them is in an appro- 
priate condition or not, but it makes no difference whatever to the 
parent insect. The latter seals up the chamber in which its eggs 
have been laid and never opens it again ; it has no chance of not- 
ing the failure or success of the food it has provided. It is clearly 
a case like that of the cocoon which cannot be explained on the 
Lamarckian theory and must be explained on the Darwinian. 
And this latter interpretation is easy : those insects which possessed 
the nervous mechanism impelling them to provide food in an ap- 
propriate condition gave to their offspring the 0|)portunity of sur- 
viving and inheritiiig the same instinct. While others, impelled 
to perform less eflicient actions, were thereby cut off from any 
representation in the next generation. 
