At Marseilles in 1868 and 1872, the newspaper reports of a case of child desertion provoked a perfect epidemic of such cases, amounting in one instance to eight in one day. Before Corridori murdered the Head-master of his boarding-school, he is said to have declared: "There will be a repetition of what happened to the Head-master at Catanzaro" (who had been murdered in the same way). The anarchist Lucchesi killed Banti at Leghorn shortly after the murder of Carnot by Caserio, and in a similar manner. Certain forms of crime which become common at given periods, the throwing of bombs, the cutting up of the bodies of murdered persons, particularly those of women, and frauds of a peculiar type may certainly be attributed to imitation, as may also the violence committed by mobs, in whom cruelty takes the form of an epidemic affecting even individuals of mild disposition. _Immigration._ The agglomeration of population produced by immigration is a strong incentive to crime, especially that of an associated nature,--due to increased want, lessened supervision and the consequent ease with which offenders avoid detection. In New York the largest contingent of criminality is furnished by the immigrant population. The fact of agglomeration explains the greater frequency of homicide in France in thickly populated districts. The criminality of immigrant populations increases in direct ratio to its instability. This applies to the migratory population in the interior of a country, specially that which has no fixed destination, as peddlers, etc. Even those immigrants whom we should naturally assume to be of good disposition--religious pilgrims--commit a remarkable number of associated crimes. The Italian word _mariuolo_ which signifies "rogue" owes its origin to the behaviour of certain pilgrims to the shrines of Loreto and Assisi, who, while crying _Viva Maria!_ ("Hail to the Virgin Mary!") committed the most atrocious crimes, confident that the pilgrimage itself would serve as a means of expiation. In his _Reminiscences_ Massimo d' Azeglio notes that places boasting of celebrated shrines always enjoy a bad reputation. _Prison Life._ The density of population in the most criminal of cities has not such a bad influence as has detention in prisons, which may well be called "Criminal Universities."