SOCIAL EVOLUTION AND SOCIAL HEREDITY 283 



lower animals, and yet every one knows of a suffi- 

 cient number of instances of young mammals being 

 brought up upon artificial food, to convince him that, 

 in spite of the lack of contact with their parents, they 

 develop identical instincts with those of their race. 

 Even the complicated instincts of the social insects 

 are included in the same general law. The common 

 bumblebee produces eggs in the fall. In the spring, 

 under the heat of the sun, they hatch each egg into an 

 individual, that has never seen its parents. This 

 individual begins at once to follow the instincts of 

 the race, builds for herself a nest, and in the course 

 of a few short weeks produces a new community with 

 the individuals differentiated and fully supplied 

 with the normal instincts of the species. Instances 

 might be multiplied ad libitum, but they are hardly 

 necessary. These few are sufficient to show that the 

 adult animal, including its instincts as well as its 

 structure, is represented in the egg. The instincts 

 are a part of the organism, and even in the egg there 

 is a structure which will inevitably develop an organ- 

 ism showing the numerous instincts as the result of 

 its delicately adjusted machinery. This does not 

 necessarily mean that there is in the egg a structure 

 as complicated as that of the adult. Over this ques- 

 tion biologists are still in dispute. It simply means 

 that in the egg there is a structure of such a nature 

 as to lead inevitably, under the influence of normal 

 conditions, to the regular structure of the adult, and 

 this includes the varied machinery upon which are 

 dependent the instincts, as well as the bones and 

 muscles. The whole problem is one of organic struc- 

 ture. 



The instincts which develop in animals may be 



