tions of the brain considered essential to those whose duty it is to bring this organ to its highest state of efficiency.
For various reasons, which it is not necessary to recapitulate, investigators interested in the study of the functions of the brain have at all times found themselves more or less in conflict with many of the accepted philosophical theories that served to obscure the issues and make progress difficult. King Frederick William's antagonism to the new ideas introduced by science into the study of psychology is a historic example of the difficulties which popular prejudice has created. This sovereign's refusal to believe in the application of the law of cause and effect to the study of mental phenomena, because he would thus be deprived of logical reasons for punishing the deserters from his Grenadier Guards, finds many analogies even at the present day.
All forms of conduct in the higher as well as the lower organisms are an expression and measure of the functional capacity of the nervous system. From the protozoa to man we can follow the constantly increasing complexity of function as revealed to us in behavior without being able to pick out a single trait as specifically characteristic of any particular organism. Herrick has called attention in a very interesting way to the fact that animals widely separated from each other in the scale of functional and structural complexity, as the annelid worms and the vertebrates, present striking differences in behavior referable to the contrasted types of nervous system represented in these two groups. The behavior of the former, stereotyped and predetermined, may be inferred from the structure just as the "plastic individual reactions of the intelligent type" are dependent upon special arrangement of the nervous mechanism of the latter. Between these two extremes are countless gradations in conduct as well as in the arrangement of the nervous system. The prevailing ignorance in regard to facts of the most elementary character relating to the structure and functions of the nervous system is well illustrated by the remarks of an English acquaintance, a graduate of Oxford and a recognized ecclesiastical authority upon matters of conduct, who when told, in reply to an inquiry, that fish had brains, after a brief period of meditation replied, "Really, that's quite an idea." What a strange comment upon our present methods of education that an individual altogether ignorant of the structural and functional capacity of the brain of a fish, which differs from the human brain only in the simpler arrangement of its elements and the greater limitation of its functions, should be considered an authority upon the training of the most complicated nervous system in the whole animal series!
The dawn of consciousness, the simplest form of memory, the element of choice in volitional acts, appear far down in the scale of living creatures, and this law of recapitulation in the behavior of organisms is