But supposing we had a trustworthy body of facts bearing upon the weight and structure of the criminal brain, we should still require to know much more of brain functions in general before satisfactory conclusions could be drawn from these facts. We know something, it is true, of the physiological functions at certain cerebral regions, but as yet nothing is known of the localisation of any particular mental faculty, whether criminal or otherwise. A conclusive proof that the study of the brain, as an organ of thought, is still in its infancy, is found in the fact that the fundamental question is still unsolved, whether the whole brain is to be considered one in all its parts, so far as the performance of psychic functions is concerned, or whether these functions are localised in certain definite centres. Till these fundamental difficulties are cleared away, the presence of anomalies in certain convolutions of the brain will not prove very much one way or the other.[35]
[35] A masterly article on the “Localisation of Brain Functions” will be found in Wundt’s Philosophische Studien Sechster Band, 1. Heft Zur Frage der Localisation der Grosshirnfunctionen, Von W. Wundt. Compare also The Croonian Lectures on Cerebral Localisation, by David Ferrier. London: 1890.
An examination of the criminal face has so far led to no definite and assured results. In the imagination of artists the criminal is almost always credited with the possession of a retreating forehead. As a matter of fact, Dr. Marro, one of the most eminent representatives of the anthropological school, assures us that this is not the case. After comparing the foreheads of 539 delinquents with the foreheads of 100 ordinary men, he found that criminals had a smaller percentage of retreating foreheads than the average man.[36] He also found that projecting eyebrows, another trait which is supposed to be a criminal peculiarity, were almost as common among ordinary people as among offenders against the law. Projecting ears is another peculiarity which is often associated with the idea of a criminal. But Dr. Lannois states that after a careful examination of the ears of 43 young offenders, he found them as free from anomalies as the ears of other people.[37]