CONTINUITY OF THE RACE 



615 



havior of the individual so radically that 

 he must be institutionalized. Because of the 

 expense involved, most states are far behind 

 in buildings and other facilities to take care 

 of all those needing such attention. The 

 situation seems to be growing worse from 

 year to year. Competent authorities who 

 have studied the problem carefully feel that 

 it will eventually reach a hopeless situation 

 unless something is done to curb the ever 

 increasing number of mentally defective 

 people. There is no doubt that many of 

 these mental illnesses, like physical defects, 

 are gene-controlled, so that a careful study 

 of them should yield some valuable infor- 

 mation to aid in guiding our future actions. 



One kind of nervous disorder, called mi- 

 crocephalic idiocy, is inherited as a reces- 

 sive, meaning that an afflicted individual 

 must have two genes for the defect. It usu- 

 ally springs up in families of normal par- 

 ents, as one might expect. However, a large 

 proportion of the children resulting from 

 the marriage of an idiot to a normal person 

 would be idiots. Fortunately such marriages 

 are rare and the line usually dies with the 

 defective person. 



Another very serious congenital disease 

 is Huntington's Chorea, in which there is 

 a marked degeneration of brain tissue, 

 resulting in poor muscular coordination, 

 twitching, and jerking movement. In addi- 

 tion, there are other associated defects 

 which contribute to produce socially and 

 mentally deranged individuals. The most 

 unfortimate part is that the disability does 

 not become apparent until middle life 

 (25-55 years of age) after most, if not all, 

 of the children have been born. Thus the 

 trait is passed on to the next generation 

 before it is recognized in the parent. Cases 

 of the disease in this country have been 

 traced back to three brothers who arrived 

 here from England in 1630. The malady has 

 shown up hundreds of times in the several 

 thousand descendants of these men, and 

 studies have revealed that about one-half 

 of the children of afflicted persons develop 



the disease some time after they are 25 

 years old. A person who knows that he 

 might develop it or pass it on to others is 

 under terrific mental strain, which in itself 

 is often sufficient to bring on nervous dis- 

 orders. 



A host of other mental disorders encom- 

 passed in the term schizophrenia are known 

 to be gene-controlled. Schizophrenics suffer 

 from delusions of persecution or grandeur 

 or they may become completely apathetic, 

 oblivious to the world around them. Such 

 response to the outside world is naturally 

 incompatible with success in society as we 

 know it. A large proportion of mental pa- 

 tients in our hospitals are schizophrenics 

 and the number seems to be increasing an- 

 nually. During times of stress, such as in 

 periods of war or depression, the number 

 seems to increase. Apparently such people 

 are on the verge of mental collapse, and 

 any undue stress is sufficient to affect the 

 breakdown. It seems that this type of insan- 

 ity itself is not inherited but is due rather 

 to a genie constitution that cannot remain 

 normal under stress. This is owing to reces- 

 sives, because schizophrenics are usually 

 found in families of normal parents, a fact 

 that makes it next to impossible to breed 

 out. 



MEDICAL GENETICS 



From such studies as those indicated 

 above, the medical profession seems to have 

 found some information of real clinical 

 value. Data accumulated by the pure ge- 

 neticists for the past fifty years is just now 

 reaching a point in its development where 

 some practical use can be made of it by 

 physicians. This has resulted in the young 

 flourishing science of medical genetics, 

 which is not to be confused with eugenics 

 (see later), a subject that has enlisted the 

 active participation of people outside the 

 field of medicine. 



Professor L. H. Snyder has cited many 

 illustrations of the use of genetics in the 



