ABSTRACT
In Part I, we attempted to show how the various mental processes devolop pari passu with the development of the nervous system. It follows that just as we have stages of growth physically so we have levels of intelligence. In a general way this is not a new thot, since every one knows that a ten year old child is more intelligent than an eight year old, and an adult more intelligent than a youth. It is, however, not appreciated that these levels are as definite as the physical stages; just as a child should be of a certain height at a certain age, so he should have a certain degree or level of intelligence. Nor is it appreciated that this development of intelligence—this growth from one level to the next higher—is inherent in the nature of the growing organism, and is not a matter of education or training. White (55) says:
