No. 398.] REVIEWS OF RECENT LITERATURE. 147 
returns of census enumerators. The result was that more or less 
complete returns were received of 4471 marriages in which one or 
both of the partners were deaf. After deducting marriages of less 
than a year’s standing, the total number of marriages of which the 
results in regard to offspring are reported is 3078, and number of 
children is 6782. These numbers are large enough to promise fairly 
trustworthy results. 
The first third of the book is taken up with a discussion of the 
results, and the rest is devoted to a tabular statement giving the 
details in regard to each marriage. This is followed by an index. 
Within the space of a review one cannot do more than refer to 
some of the conclusions which are of especial interest. Passing over 
the statistics in regard to the relative fertility of the deaf and the 
hearing, the proportion of deaf children in the total marriages of the 
deaf, etc., we come to a comparison between the proportion of deaf 
children born when both parents are deaf and the number when one 
parent only is in this condition, and we find the surprising result 
that in the first case there are only 8.458 per cent of deaf children, 
while in the second there is a considerably larger percentage, namely, 
9.856. This would seem to upset all one's ideas of heredity. But 
the anomaly is explained to a great extent when we take into con- 
sideration the nature of the deafness, whether congenital or acquired, 
the ancestry of the parents, and their relationship to one another. 
The author calls attention to the fact that deafness may be due to 
a number of causes, such as various infectious diseases, malformation 
of various auditory organs, and the like. It is not deafness as such 
that is inherited, but some tendency to disease, or some abnormal 
habit of growth. This makes it difficult to distinguish deafness 
which is congenital and that which is adventitious, even when the 
patient can be examined; and it is still more difficult to make the 
distinction from the reports of cases such as were used in this 
inquiry. Therefore it is not a matter of surprise that the author 
fails to give a good definition of the two kinds of deafness. 
Notwithstanding this uncertainty of definition, the results as to the 
relative frequency of deafness in children of congenitally deaf parents 
and parents adventitiously deaf are decidedly interesting. Thus it is , 
found that where both parents are congenitally deaf the percentage 
of deaf children is 2 5.931; where one parent is congenitally deaf and 
the other adventitiously deaf it is 6.538 ; while where both parents are 
adventitiously deaf it is but 2.326. But where one parent 1s con- 
genitally deaf and the other hearing 11.932 per cent of the children 
