Has the criminal any bodily and mental characteristics which differentiate him from the ordinary man? Does he differ from his fellows in height and weight? Does he possess a peculiar conformation of skull and brain? Is he anomalous in face and feature, in intellect, in will, in feeling? Is he, in short, an individual separated from the rest of humanity by any set or combination of qualities which clearly mark him off as an abnormal being? As these matters are at present exciting considerable attention, let us now look at the criminal from a purely biological point of view.  
A good deal of diversity of opinion exists among competent authorities respecting the stature of criminals. Lombroso says that Italian criminals are above the average height; Knecht says German criminals do not differ in this respect from other men; Marro says the stature of criminals is variable; Thomson and Wilson say that criminals are inferior in point of stature to the average man. Whatever may be the case on the Continent, there can be little doubt that as far as the United Kingdom is concerned, the height of the criminal class is lower than that of the ordinary citizen. In Scotland the average height of the ordinary population is (559) 67.30 inches; the average height of the criminal population, as given by Dr. Bruce Thomson, is (324) 66.95 inches. According to Dr. Beddoe, the average height of the London artizan population is (318) 66.72 inches; the average height of the London criminal (300) 54.70 inches; the average height of Liverpool criminals, according to Danson, is (1117) 66.39 inches. Danson's figures point to the fact that there is hardly any difference in height between the criminal classes of Liverpool and the artizan population of London It has, however, to be borne in mind that the population of the North of England, being largely of Scandinavian descent, is taller than the population of the South of England. The height of Liverpool criminals should be compared with the average height of the Scotch, to whom they are more nearly allied by race. If this is done, it will be seen that they fall considerably short of the normal stature.
 
The difference between the height of the criminal population and that of the most favoured classes is more remarkable still. According to Dr. Roberts' tables, the average height of the latter is 69.06 inches; the London criminal is only 64.70 inches. There is thus a difference of from four to five inches between the most highly favoured classes and the London criminal class. The difference between the criminal class and the merely well-to-do is not quite so great. Selecting Mr. Galton's Health Exhibition measurements as a test of the stature of the well-to-do classes, the results come out as follows:—Health Exhibition measurements, 67.9 inches; London criminals, 64.70 inches. The criminal is thus between two and three inches inferior in height to the well-to-do portion of the community. In fact, the height of the London criminal is very nearly the same as that of the East-End Jew. According to Mr. Jacobs, in a paper communicated to the Journal of the Anthropological Institute, the average stature of the East-End Jew is 64.3 inches; his co-religionist in the West-End is 67.5 inches. We may accordingly take it as the outcome of these measurements that the criminal population of Great Britain is inferior in point of stature to the ordinary population.
 
From stature we shall pass to weight. Lombroso and Marro say that the weight of Italian criminals is superior to the weight of the average Italian citizen. On the other hand, the weight of London criminals is almost the same as that of London artizans, but inferior to the weight of the artizan population in the large English towns taken as a whole. Average weight of London criminals (300) 136 pounds; average weight of London artizan (318) 137 pounds; average weight of artizans in large towns generally, 138 pounds. The London criminal is considerably inferior in weight to the well-to-do classes, as will be seen from Mr. Galton's Health Exhibition statistics. Average weight, Health Exhibition, 143 pounds; average weight, most favoured class (Roberts), 152 pounds. These figures show that the criminal class in London is seven pounds lighter than the well-to-do, and sixteen pounds lighter than the most favoured section of the population.
 
Hardly any investigations have been made in this country respecting the skulls of criminals, and the inquiries of continental investigators have so far led to very conflicting results. It is a contention of Lombroso's that the skulls of criminals exhibit a larger proportion of asymmetrical peculiarities than the skulls of other men. On this point Lombroso is supported by Manouvrier. But Topinard, an anthropologist of great eminence, is of the opposite opinion. He carefully examined the same series of skulls as been examined by Manouvrier—the skulls of murders—and he discovered no marked difference between these and other skulls. Heger, a Belgian anthropologist says that the skulls of delinquents do not differ from the skulls of the race to which the delinquent belongs. In fact, till more exactitude is introduced into the methods of skull measurement, all deduction based upon an examination of the criminal skull must be regarded as untrustworthy. A striking instance of this was witnessed at the proceedings of the Paris Congress of Criminal Anthropology held in 1889. When the skull of Charlotte Corday, who killed the revolutionist Marat, was subjected to examination, Lombroso declared that it was a truly criminal type of skull; Topinard, on the other hand, gave it as his opinion that it was a typical female skull. On this point Topinard was supported by Benedict.[34] As long as such divergencies of view exist among anthropologists it is impossible to place much stress upon inquiries relative to the conformation of the criminal skull. Before a beginning can be made with inquiries of this character, there must be some fundamental basis of agreement among investigators as to what is to be accounted asymmetrical in skull measurements and what is not. Even then it will have to be remembered, before coming to conclusions, that no skull is perfectly symmetrical—every one showing some variation from the ideal type. When the extent of this variation has been absolutely demonstrated to be greater in the case of criminals than among other sections of the community, we shall then be approaching solid ground. At present we must wait for further light before anything can be said with certainty with respect to the criminal skull.
 
Just as little is known at present about the brain of criminals as about the skull. Some years ago Professor Benedict startled the world by stating that he had discovered the seat of crime in the convolutions of the brain. He found a certain number of anomalies in the convolutions of the frontal lobes, and he came to the conclusion that crime was connected with the existence of these anomalies. But he had omitted to examine the frontal convolutions of honest people. When this was done by other investigators, it was found that the brain convolutions of normal men presented just as many anomalies, some investigators (Dr. Giacomini) said even more than the brains of criminals. According to Dr. Bardeleben, there is no such thing as a normal type of brain. Weight of brain is a much simpler question than brain type, but so far it is impossible to say whether the criminal brain is heavier or lighter than the ordinary brain. The solution of this comparatively simple point is beset by a certain number of obstacles. It is not enough, Dr. Binswanger tells us, to weigh the brains of criminals and the brains of ordinary persons and then strike an average of the results. The height and weight of the persons whose brains are averaged are essential to the formation of accurate conclusions; till these important factors are taken into account, all deductions based upon weight of brain only rest upon an unsure foundation.
 
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]
 
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]
 
As it is the Italians who have studied these matters most exhaustively, it is mainly to them we must go for information. In a little book on the skeleton and the form of the nose, Dr. Salvator Ottolenghi comes to the somewhat curious result that the bones of the criminal nose offer many anomalies of a pre-human or bestial character; but the nose itself is straight and long, or, in other words, just as highly developed as the noses of ordinary men. Careful inquiries have been undertaken by criminal anthropologists into the colour of the hair, the length of the arms, the colour of the skin, tattooing, sensitiveness to pain among the criminal population, but these laborious investigations have so far led to few solid conclusions. According to Lombroso, insensibility to pain is a marked characteristic of the typical criminal.[38] "Individuals," he says, "who possess this quality consider themselves as privileged, and they despise delicate and sensitive persons. It is a pleasure to such hardened men to torment others whom they look upon as inferior beings." On this point M. Joly is at variance with Lombroso. "I asked," he says, "at the central hospital, the Santé, where all persons who become seriously ill in the prisons of the Seine are looked after, if this disvulnerability had ever been noticed. I was told that far from that, prisoners were always found very sensitive to pain ... Honest people, industrious workmen, the fathers of families treated at the Charité or the Hôtel-Dieu (Paris hospitals), undergo operations with much more fortitude than the sick prisoners of the Santé."[39] On this point, therefore, as on so many others, we are still without a sufficient body of evidence, and must, meanwhile, suspend our judgment.
 
Let us now consider the criminal's physiognomy. In this connection it must be borne in mind that a prolonged period of imprisonment will change the face of any man, whether he is a criminal or not. Political offenders who have undergone a sentence of penal servitude, and who may be men of the highest character, acquire the prison look and never altogether get rid of it. If a man spends a certain number of years sharing the life, the food, the occupations of five or six hundred other men, if he mixes with them and with no one else, he will inevitably come to resemble them in face and feature. A remarkable illustration of this fact has recently been brought to light by the Photographic Society of Geneva. "From photographs of seventy-eight old couples, and of as many adult brothers and sisters, it was found that twenty-four of the former resembled each other much more strongly than as many of the latter who were thought most like one another."[40] It would, therefore, seem that the action of unconscious imitation, arising from constant contact, is capable of producing a remarkable change in the features, the acquired expression frequently tending to obliterate inherited family resemblances. According to Piderit, physiognomy is to be considered as a mimetic expression which has become habitual. The criminal type of face, so conspicuous in old offenders, is in many cases merely a prison type; it is not congenital; men who do not originally have it almost always acquire it after a prolonged period of penal servitude.
 
But apart from the prison type of countenance, it is highly probable that a distinct criminal type also exists. Certain professions generate distinctive castes of feature, as, for instance, the Army and the Church. This distinctiveness is not confined to features alone, it diffuses itself over the whole man; it is observable in manner, in gesture, in bearing, in demeanour, and is constantly breaking out in a variety of unexpected ways. In like manner the habitual criminal acquires the habits of his class. Crime is his profession; it is also the profession of all his associates. The constant practice of this profession results in the acquisition of a certain demeanour, a certain aspect, gait, and general appearance, in many instances too subtle to define, but, at the same time, plain and palpable to an expert.
 
The slang of criminals is also explicable on the same principle. Every trade and calling has its technical terms. The meaning of these terms is hidden from the rest of the world, but the origin of their existence is not difficult to explain. The jargon of the criminal arises from the same causes and is constructed on exactly the same principles as the technical words and phrases of the man of science. When a man of science is compelled to make frequent use of a phrase, he generally gets rid of it by inventing some technical word; it is precisely the same with criminals. With them technical words are used instead of phrases, and short words instead of long ones in all matters where criminal interests are intimately concerned, and on all topics which are habitually the subjects of conversation among the criminal classes. The language of the Stock Exchange with its Bulls, Bears, Contangos, and other short and comprehensive expressions for various kinds of stocks, is on all fours with the slang of criminals, and it is not necessary to resort to atavism in order to explain it. It arises to supply professional needs, and criminal argot springs up from exactly the same cause.
 
Summing up our inquiries respecting the criminal type we arrive, in the first place, at the general conclusion, that so far as it has a real existence it is not born with a man, but originates either in the prison, and is then merely a prison type, or in criminal habits of life, and is then a truly criminal type. As a matter of fact, the two types are in most cases blended together, the prison type with its hard, impassive rigidity of feature being superadded to the gait, gesture and demeanour of the habitual criminal. In combination these two types form a professional type and constitute what Dr. Bruce Thomson[41] has called "a physique distinctly characteristic of the criminal class." It is not, however, a type which admits of accurate description, and its practical utility is impaired by the fact t............