When it is too late they are "listed" as not suitable for prison treatment.

Year by year in a country of presumably sane people this deplorable condition of things continues, and I am bold enough to say that there will be no reduction in the number of our prison population till proper treatment, training, and, if need be, detention, is provided in places other than prison for our afflicted youthful population when they become offenders against the law.
But reformatory and industrial schools have not only power to refuse youthful delinquents who are unsound in mind or body; they have also the power to discharge as "unfit for training" any who have managed to pass the doctor's examination, whose defects become apparent when under detention.
From the last Official Report of Reformatory Schools in England and Wales I take the following figures-- During the years 1906-7-8 14 imbeciles (males) were discharged on licence from reformatory schools; and during the same three years no less than 93 (males) were discharged by the Home Secretary's permission as "unfit for physical training." The 14 imbeciles in the Official Report are classified as dead, and the 93 physically unfit are included among them "not in regular employment." For the same period of years I find that 28 (girls) were discharged from English reformatory schools as being physically unfit.
The Official Report of Industrial Schools includes England, Wales and Scotland, and for the same three years I find that 13 (males) were discharged from industrial schools as being imbeciles, and 116 (males) as being "unfit for physical training." Strange to say, in the Annual Report the physically unfit are included among those "in casual employment," and the imbeciles are included among the "dead." From the same Official Report we have the statement that in one year, 1909, in England and Scotland 991 (males) and 20 (females) who had been discharged from reformatory schools were re-convicted and committed to prison.
How many of them were mentally or physically defective we have no means of knowing, for no information is given upon this point; but there is not the slightest doubt that a large number of them were weak-minded, though not sufficiently so to allow them being classified as imbeciles.
The terrible consequence of this procedure may also be gathered from the Report of the Prison Commissioners for England and Wales 1910, from which it appears that during the year 157 persons were certified insane among the prisoners in the local and convict prisons, Borstal institutions and of State reformatories, during the year ending March 31, 1910.
In addition to the above there were 290 (213 males and 77 females) cases of insanity in remanded and other unconvicted prisoners dealt with during the year, including 14 males and 2 females found "insane on arraignment," and 173 males and 65 females found insane on remand from police or petty sessional courts.

There were 30 (20 males and 10 females) prisoners found "guilty" but "insane" at their trial.
But the most illuminating report comes from the medical officer at Parkhurst Convict Prison; these are his words-- Weak-minded convicts and others whose mental state is doubtful continue to be collected here.

The special rules for their management are adhered to.

The number classified as weak-minded at the end of the year was 117, but in addition there were 34 convicts attached to the parties of weak-minded for further mental observation.
"The conduct and tractability of these prisoners naturally vary with the individual; a careful consideration of the history of each of the 117 classified weak-minded convicts indicates that about 64 are fairly easily managed, the remainder difficult to deal with, and a few are dangerous characters.
CLASSIFICATION OF WEAK-MINDED CONVICTS:-- (a) Congenital deficiency:- 1.