I50 THE POPULAR SCIENCE MONTHLY 



feet development of them. A defective child goes through the stages 

 of its development more slowly than the normal child, and fails to reach 

 the later stages. Such a child has not a different heredity from the 

 normal child, but simply a less complete expression of it. If this is 

 true, defects measure environmental control. Every defect has some 

 objective cause which acts as a check on normal growth. "We make 

 progress, therefore, in the study of defects as we connect them with bad 

 environments. 



We can thus detect physical defects. To ascertain and measure 

 mental defects the needed criterion is found in the law of the associa- 

 tion of ideas. If a mental defect has at its basis a harmful association 

 of ideas, we may confidently affirm that its origin is environmental. AU 

 ideas are postnatal, and hence all associations must be formed after 

 birth. We do not need a biologic character to create a new association 

 of ideas, but only some reorganization of experience. In harmony 

 with these facts and principles there should be four stages of child 

 development, which appear in the following order : 



1. The elementary life stage. 



2. The sensory stage. 



3. The stage of bone formation. 



4. The motor stage. 



On the basis of this analysis, there should be a t}'pe of man who has 

 the elementary vital functions, but lacks the later organic developments. 

 That such a type exists can be shown, and its indices readily pointed 

 out. This type has high cheek bones, a sloping forehead, a flat, broad 

 nose, and a defective lower face and chin. The central part of the 

 face is fully developed, while its upper and lower parts are imperfect. 

 The people of this type are short in stature, broad at the hips, and 

 round-headed. All the vital functions are normally developed, but tlie 

 later stages of growth are defective. Such people thrive in a simple 

 environment, especially if they have a pictorial religion and a conven- 

 tionalized morality. 



A second physical type is also easily described. Here the upper 

 part of the head is fully developed, and the central part of the face is 

 defective ; the nose is peaked and narrow at the base ; the teeth are bad ; 

 the mouth is small ; and the chin is pointed. This physical description 

 has a meaning that can be readily interpreted. The retardation has 

 taken place late in pregnancy after the brain has passed through its 

 initial development. A child's face lengthens downward as the child 

 matures. A weak, short lower-face indicates, therefore, a stoppage of 

 growi;h after the middle-face and upper-face have been formed. A per- 

 son of this type is likely to be short and thin and have a poorly devel- 

 oped bone structure. The type is usually regarded as intellectual when 

 contrasted with the first type, which is often designated as sexual. 



