HEREDITY AND MANIC-DEPRESSIVE PSYCHOSES 341 



that 42 additional cases will arise among the brothers, sisters or other rela- 

 tives, the minimum number necessary to effect a significant change in the 

 results. 



Among fathers, there were 4 expected cases and 3 actual cases; among 

 mothers, expected 4, and actual 4; among grandfathers, expected 6, actual 2; 

 among grandmothers, expected 6, actual 2; among uncles, expected 10, 

 actual 4; among aunts, expected 10, actual 4; among brothers, expected 12, 

 actual 11; and among sisters, expected 10 and actual 10. In none of these 

 degrees of relationship can the divergence between actual and expected 

 results be considered significant. In the case of brothers and sisters the 

 total of affected individuals will however, undoubtedly exceed the expected 

 total in the course of time. 



Among the 95 female patients, we find 22 cases in which the father had 

 some mental or nervous defect or disease. The patients represented in these 

 22 families had 154 brothers and sisters with known histories. Of these 

 7 developed psychoses, compared with an expected total of 6.6. Additional 

 cases may be expected before the generation has completed its span of life. 

 Considering the 19 families in which the mother of the patient showed a 

 mental or nervous disorder we find that there were 105 siblings, among 

 whom there were 7 psychoses, compared with an expectation of 4.8 cases. 

 Making allowances for the incompleted lives of the generation and for the 

 12 brothers and sisters who showed some mental or nervous disorder other 

 than that of a recognized psychosis we may state that there is a strong 

 probability that the difference between actual and expected results is sig- 

 nificant and indicates a preponderance of mental disease in the siblings of 

 these patients. 



Taking all types of mental disease into consideration we may conclude 

 that the frequency of affected individuals in the families of the 60 male and 

 95 female patients with manic-depressive psychoses does not seem to point 

 to a hereditary explanation of the origin of mental disease in this stock. 

 When we select those cases in which the father of the patient was affected, 

 we again find inconclusive results. But when the mother was affected, 

 we find reason for believing that the frequency of affected children was 

 greater than the expected. The results are clear cut in the case of the 

 female patients, and in view of the greater total of such cases to begin with, 

 these results should be given greater weight than in the case of the families 

 of the male patients. 



We have, however, been dealing with an aspect of the polymorphic theory 

 of the transmission of mental disease. Let us now consider the facts with 

 relation to the manic-depressive psychoses exclusively. We have no 



