For the segregation of the graver criminals, the management must be as scientific as it is now in insane asylums.

It is absurd to impose segregation in prison for small errors.

For the graver crimes committed by atavistic or congenital criminals, of by persons inclining toward crime from acquired habit or mental alienation, the positive school of criminology reserves segregation for an indefinite time, for it is absurd to fix the time beforehand in the case of a dangerous degenerate who has committed a grave crime.

They are not so usual as to hotels, eating-houses, theatres, or other public places, probably because in such it is more easy to secure the desired segregation without legislation.