118 THE EVOLUTION OF INSTINCT 
The Lamarckian theory of the origin of instinct has in 
more or less modified forms enjoyed a wide popularity among 
writers on genetic psychology. The veteran psychologist 
‘Wundt in his discussion of theories of instinct in his Human 
and Animal Psychology assumes unquestioningly the trans- 
mission of acquired characters, practically ignoring the 
doctrine of natural selection, and even representing that 
Darwin “explains instinct as inherited habit”! 
One of the most extreme positions is that of Eimer who 
rejects the theory of natural selection and adopts the pure 
Lamarckian standpoint. One of his arguments in favor of 
this theory is drawn from the instincts of the mason wasp, 
Odynerus parietum. This species provisions its nest with 
larve which it paralyzes by stinging them in the ventral 
ganglia. After collecting several larve and storing them 
in a hole in the ground, the wasp lays an egg on the store of 
food, seals up the hole with clay, and then begins the con- 
struction of another nest. “What a wonderful contrivance”! 
exclaims Eimer, “What calculation on the part of the animal 
must have been necessary to discover it! The larve of the 
wasp require animal food. Dead food enclosed in the cell 
would soon putrefy; living active animals would disturb the 
egg, and accordingly the wasp paralyzes grubs and packs 
them like sacks of meal one after another in the cell. How 
did she arrive at this habit? At the beginning she prob- 
ably killed larve by stinging them anywhere and then 
placed them in the cell. The bad results of this showed 
themselves; the larve putrefied before they could serve 
as food for the larval wasps. In the meantime the mother- 
wasp discovered that those larve which she had stung in 
particular parts of the body were motionless but still alive, 
and then she concluded that larve stung in this particular 
way could be kept for a longer time unchanged as living 
