Figure C 13 showing the inheritance of progressive muscular atrophy (after Eichhorst).
Figure C 14 a partial reproduction of a pedigree comprising over 2,000 people of the family Nongaret suffering from inherited stationary night blindness (compiled by Cunier, Truc and Nettleship). With regard to these figures it is to be noted that only a fraction of the offspring is affected with the illness, the remainder being perfectly normal. It is remarkable with the bleeders (Hæmophilic persons) that the females do not suffer from the disease though they transfer it to their male offspring; a similar latent disposition is observable in other hereditary conditions, especially colour-blindness.
W. Weinberg shows in Table C 15 the frequency of tuberculosis within families. He adds: "This is a comparison of the experiences of married tubercular individuals, regarding the frequency of tuberculosis among their parents, brothers and sisters, with the corresponding experiences of their husbands or wives who come on an average from similar surroundings. The experiences of the latter represent the normal expectation. It is especially striking that the family influence tells most with the children of the well-to-do." The well-known fact that the tuberculous frequently come from tuberculous stock is clearly demonstrated in the figures of this table.
In Table C 16 Dr. Otto Diem shows the distribution of particular taints in every hundred of the tainted members among the nearest relations (parents, grandparents, uncles, aunts, brothers and sisters) of the entire material he deals with. It is shown for instance that with the mentally sound, 15% of the tainted relatives were mentally diseased against 45.9% with the mentally diseased. Figure C 17 shows the share of this percentage among the parents only. It is demonstrated that with the mentally diseased a much larger percentage of the total hereditary taint is traceable to parental madness, alcoholism, abnormality of character, than with the mentally sound.