This scale devised for the school children of France has been tested in the elementary schools of Italy and of the United States. It has been found to be right in principle, although tests and ages require some slight adjustment when applied to children of other races than the French.
Now when we apply these tests to the unfortunate people denominated imbeciles and feeble-minded, we make the surprising discovery that some of them, although they may live to an advanced age, are never able to perform the tasks allotted to a child of three and that none of them can do more than pass the tests suitable to a child of ten. Here then is the explanation of mental defect; it is the failure of the mind to develop further than to a certain stage. The next step was to ascertain whether or not this unfortunate character was hereditary, and the merit of solving this, perhaps the most important of eugenic problems, must be accorded to Dr. Goddard,[1] a doctor attached to the staff of the Vineland Institution for insane and mentally defective children in the state of New Jersey. This institution is a charitable one, which takes in defective children and gives them the best education which they are capable of receiving. All the inmates are tested on admission, and at suitable intervals afterwards, by the Simon-Binet scales.
Now Dr. Goddard secured the services of a certain number of educated investigators, who received a special course of training in the institution itself and were then sent forth to investigate the ancestry of the inmates so far as this could be accomplished. This they did by gaining the confidence of the relatives of the inmates, to whom the acceptance of the care of their afflicted children by the Vineland Institution was a great boon, and who were naturally anxious to learn about their progress and quite ready to talk about the first appearance of what to them was an ordinary malady. In this way the investigator was enabled to find out whether any of the brothers or sisters of a particular child were mentally defective, whether his parents or his grand-parents had been similarly affected, or whether there were circumstances pointing to some accident as the cause of the trouble. By proceeding along these lines it was possible to draw up an ancestral chart for each inmate of the institution. In this chart a square indicated a male relative, a circle a female; if it appeared that the relative was mentally defective the square or circle was blackened—if on the other hand the relative was clearly normal a square (or circle as the case might be) with the letter N inscribed was placed on the chart. Where definite information was lacking a blank square or circle was added.
The chart was revised at intervals, a fresh investigator being employed for the research on which the revision was based. In practically no case did renewed inquiry lead to the conclusion that relatives formerly regarded as defective were really normal; on the contrary, at every fresh examination more doubtful cases resolved themselves into definitely feeble-minded ones and the child's chart was correspondingly blackened.
The net results of Dr. Goddard's investigations were as follows. In the case of 6,000 children a mentally defective ancestor was ascertained; and about one-fourth of these children were definitely feeble-minded and about one-fourth definitely normal; the mental condition of the remainder could not be ascertained. In the case of 1,500 children there was a definite history of an accident which might be regarded as the cause of the mental condition, and 804 children are classified as of "neuropathic" ancestry, i.e. the descendants of epileptic or hysterical parents, a condition which seems akin to feeble-mindedness. It should be remarked that these numbers included not only the inmates of the institution but their brothers and sisters and cousins who were outside and many of whom were quite normal mentally. Where both parents were mentally defective practically all the children were feeble-minded: out of 750 such children investigated only six were reported as normal; and considering the low grade of sexual morality maintained by such people the parentage of these children must be the subject of considerable doubt. In the case of one such family, where both parents were mentally defective, two children out of a large number were normal but these two were black and therefore of obvious illegitimate origin. Where one parent was defective and the other, though normal, had a defective ancestor, then as a rule some of the children in the family were defective and others normal. The same results were obtained where both parents themselves were normal but where one of them was descended from a defective ancestor.
Now these results are in accord with the newest and best-attested results of researches into the inheritance of certain characters in the lower animals and in plants; the laws governing this kind of inheritance are termed Mendelian because they were first ascertained by Gregor Mendel, an Augustinian monk in the middle of the igth century. Mendel's work was unnoticed by most of his contemporaries and was only rediscovered and confirmed by further research in 1900. Briefly the laws which he discovered may be summarized thus:—
(1) In different breeds or strains of the same species characters often appear in pairs so that only one of the pair appears in one strain: such characters are termed allelomorphs. (2) When two such strains are crossed, in the first generation of hybrids only one of the allelomorphs appears: this is termed the dominant character; the allelomorph which fails to appear is termed the recessive character. (3) If the first generation of hybrids be used as parents of a second generation of hybrids, one-fourth of these will exhibit the recessive character, and these if used to propagate a further generation will give rise to nothing but recessives for however many generations propagation may be carried on. (4) In cases (such as plants) where self-fertilization is possible the three-fourths of the second hybrid generation which exhibit the dominant character can be individually tested as to their hereditary potentialities. It is then found that one-third of them (i.e. one-fourth of the whole generation) give rise to nothing but dominants, but the remainder (i.e. one-half of the whole generation) behave as did the first generation of hybrids, i.e. each gives rise to progeny three-fourths of which exhibit the dominant character and one-fourth the recessive character.
These results were interpreted by Mendel as proving that the first generation of hybrids produced two kinds of germ cells in equal numbers, each kind bearing one of the allelomorphic characters, and that these two kinds were mixed at random in fertilization. Bateson and Punnett[2] later gave reasons for believing that the recessive quality of a character was due to the fact that it was caused by the absence of something which was present in the dominant, and that when two germ cells united in fertilization, if one of them bore the dominant character, that was sufficient to ensure the appearance of that character in the resulting organism.
Menfal defect is therefore a recessive character due to the want of something in the fertilized egg which gives rise to the mentally defective child, something which is present in the germ from which the healthy child originates. We now understand why two defective parents can give rise only to defective children and why a normal child can spring from the union of a normal and a defective parent, and further why such a child may in turn give rise to defective children as well as to normal ones.
The social implications of this discovery are fundamental and far-reaching. We see at once and this is in accordance with the experience of the Vineland authorities why all efforts to raise the mentally defective above a certain level by education are bound to fail. Further, we see that unless such defectives are segregated for life and prevented from breeding they constitute a constant source of potential poison to the race.
If we regard all children who fail to attain a greater mental age than nine as defective, they can be conveniently arranged in three groups, viz. (a) those who never attain a mental age of more than three years, who are termed idiots; (b) those who never attain a mental age of more than six years, who are termed imbeciles; whilst (c) those reaching mental ages of seven, eight and nine years are termed in English law "feeble-minded," but by the American authorities "morons" (Gk., μώρος, foolish). Neither idiots nor imbeciles constitute a social danger since their incapacity is so great that they are unable to support themselves in the ordinary battle of life and must therefore be maintained
