28 



parent curves. There is a greater incidence of insane mothers under 30 than fathers ; this is 

 due to puerperal cases, of which there were a fair number. These figures (16 and 17) are 

 constructed upon the data contained in Table I. The abscissae represent the age periods and 

 the ordinates the percentages of cases whose ages at the time of attack is first given. 



Collateral Heredity. 



The following table is compiled from 193 pairs of uncles and aunts with nephews and nieces 

 in which only collateral heredity is manifested, and 231 pairs of uncles and aunts with nieces or 

 nephews, in which are included those instances where one or both parents of the nieces and 

 nephews are also insane. The figures denote the percentage of cases whose first attack occurred 

 within the given age periods. 



TABLE II. 



UNCLES Ann AUNTS 



;wS/N4oWilcS 



COLLATERAL ONLY 



V 



Fig. 1 8 Fig. 19 



Fig. 1 8 shows the curves of uncles and aunts and nephews and nieces constructed from the 

 percentages in Table II. Fig. 19 shows the curves of uncles and aunts and nephews and 

 nieces, including those cases where one of the parents was also insane, so that there is direct 

 and collateral heredity. It will be observed that there is a considerable difference in the 

 offspring curves. When there is only collateral heredity there are a far larger number of 

 offspring in which the first attack occurred in the later periods of life, There is antedating, 

 but it is not nearly so marked as is shown in Fig. 19; nor is it nearly so marked as in parents and 

 offspring, Figs. 16 and 17. These figures are constructed from the daca contained in Table II. 



