A depraved environment, which counsels or even insists on wrong-doing, and the bad example of parents or relatives, exercise a still more sinister influence on children than desertion. The criminal family Cornu, finding one of their children, a little girl, strongly averse to their evil ways, forced her to carry the head of one of their victims in her pinafore for a couple of miles, after which she became one of the most ferocious of the band. _Meteoric Causes_ are frequently the determining factor of the ultimate impulsive act, which converts the latent criminal into an effective one. Excessively high temperature and rapid barometric changes, while predisposing epileptics to convulsive seizures and the insane to uneasiness, restlessness, and noisy outbreaks, encourage quarrels, brawls, and stabbing affrays. To the same reason may be ascribed the prevalence during the hot months, of rape, homicide, insurrections, and revolts. In comparing statistics of criminality in France with those of the variations in temperature, Ferri noted an increase in crimes of violence during the warmer years. An examination of European and American statistics shows that the number of homicides decreases as we pass from hot to cooler climates. Holzendorf calculates that the number of murders committed in the Southern States of North America is fifteen times greater than those committed in the Northern States. A low temperature, on the contrary, has the effect of increasing the number of crimes against property, due to increased need, and both in Italy and America the proportion of thefts increases the farther north we go. _Density of Population._ The agglomeration of persons in a large town is a certain incentive to crimes against property. Robbery, frauds, and criminal associations increase, while there is a decrease in crimes against the person, due to the restraints imposed by mutual supervision. "He who has studied mankind, or, better still, himself [writes my father], must have remarked how often an individual, who is respectable and self-controlled in the bosom of his family, becomes indecent and even immoral when he finds himself in the company of a number of his fellows, to whatever class they may belong. The primitive instincts of theft, homicide, and lust, the germs of which lie dormant in each individual as long as he is alone, particularly if kept in check by sound moral training, awaken and develop suddenly into gigantic proportions when he comes into contact with others, the increase being greater in those who already possess such criminal tendencies in a marked degree." In all large cities, low lodging-houses form the favourite haunts of crime. _Imitation._ The detailed accounts of crimes circulated in large towns by newspapers, have an extremely pernicious influence, because example is a powerful agent for evil as well as for good.