128 THE EVOLUTION OF INSTINCT 
solitary forms and the highly organized social state repre- 
sented by the hive bee. The various grades of social life 
which these insects present have been described in a very 
interesting little treatise by Buttel-Reepen on ‘ Die stam- 
msgeschichtliche Entstehung des Bienenstaates.”” The series 
of forms which Buttel-Reepen describes indicates very 
clearly that there has been a gradual specialization of 
function in the queen from a condition in which she performed 
all the duties of the household to one in which her functions 
are confined practically to reproduction. A sort of division 
of labor has come about so that the workers and the queen 
together perform the labors formerly accomplished by 
the queen alone. Herbert Spencer is therefore in the main 
right in his contention that the fact that the neuters have 
instincts not found in the queen is due to the queen’s having 
lost them in specializing in the direction of increased capacity 
for reproduction. It is possible to maintain, therefore, that 
the transmission of acquired characters may have moulded 
the instincts of the worker caste up to that point in social 
evolution at which they came to be practically sterile. 
The differences between the queen and worker are 
occasioned by differences in food. With a diminution of 
the food supply and a consequent arrest of development 
of the organs of reproduction there is a suppression of the 
reproductive instincts, but the fostering and household 
instincts are retained. The worker, we might say, halts at 
a phyletically older period. The queen with a richer food 
supply develops beyond to a stage in which what might 
have become worker characters are suppressed in the interest, 
perhaps of greater reproductive efficiency. The condition 
might be compared to what is found in certain parasitic 
isopods in which the adult female after having passed through 
aetive and highly organized stages of metamorphosis comes 
