78 



The Journal of Heredity 



there is abundant proof of differences 

 in susceptibility in different families, 

 and in different members in the same 

 family. It has been noted (Park and 

 Zinj^her) that when the younj^est mem- 

 ber of the family ^nves a neKati\-e 

 Schick reaction, on the introduction 

 of dii:)htheria toxin, the rest of the 

 members of that family, will also give 

 a nej^'ative reaction, showinj^ that they 

 are all immune to a diphtheritic infec- 

 tion. As an illustration of a difference 

 in susce])tibilily or resistance in children 

 of the same family, I may cite a recent 

 experience. In a family in which there 

 were three children, the oldest, who was 

 five years of a<je was attacked with 

 measles. He infected the other two 

 children, two \-ears, and eight months 

 of age resjjcctively. The younger had 

 an extremely mild attack of the dis- 

 ease, as infants under 9 months usually 

 do; but the older had an extremely 

 severe attack with com i)licat ions, and 

 died. 



Years ago, the French school es- 

 pecially laid great stress on the so-called 

 diatheses. They were, of course, very 

 much overdone; but now the ]jendulum 

 has swung a little too far in the other 

 direction, and the diatheses have been 

 ver\- largely discarded as factors in the 

 causation of disease. A similar change 

 has taken place in the use of venesec- 

 tion. At one time, practically all ail- 

 ments were treated by blood letting, 

 and probably in some cases very great 

 injury was done; but now, it is often not 

 done in cases in which it might be life 

 saving. I believe all pediatrists will 

 admit that there are two diatheses, 

 namely, the so-called exudative, and the 

 spasmophilic, diatheses. 



PATHOLOGIC SYMPTOMS OFTEN SOUGHT 



In the etiology of diseases not dis- 

 tinctly of microbial origin, tuberculosis, 

 syphilis, and alcoholism, are constanll\' 

 sought. These conditifms do undouln- 

 edly often play an imjiortant part: but 

 since the introduction of the Wasser- 

 mann reaction, the rdle of sy])hilis has 

 certainly attracted too much attention. 

 Everyone admits that the etiological 

 im]X)rtance of syphilis was fonnerlv 

 freciuenlly overlooked f)r unrecognized; 



but now its irrjiortance is surely over- 

 estimated, especially in conditions which 

 are inherited. Recently Holt reported 

 that in fifty-six children with various 

 congenital anomalies, the Wassennann 

 reaction was negative in every case. 



When no other plausible explanation 

 of a congenital disease is obtainable, 

 toxemia, during j^regnancy, is a favf)rite 

 solution of the> difficulty. As an illus- 

 tration, take amaurotic family idiocy. 

 Hirsch believed that it was due to some 

 toxic substance in the mother's milk. 

 But the disease has occurred in infants 

 who were artificially fed; the same 

 mother ma\' give the breast in turn to 

 several children, and some will develop 

 the disease while others will remain 

 normal. That the disease is not due 

 to any disease or toxemia of the mother 

 during pregnancy, is shown by the fact 

 that the mother may have alternately 

 a nonnal and an abnormal child. 

 (Fig. 16.). I have reported (Archives 

 of Pediatrics, December, 1915) a case of 

 amaurotic family idiocy in one of twins, 

 the other child developing in a i^erfectly 

 normal manner. It is very difficult to 

 conceive of any form of toxemia in the 

 mother that would affect only one of 

 twins. The two children were fed in 

 exactly the same way; they lived in 

 exactly the same surroundings. On a 

 hereditary basis it is not difficult to 

 ex])lain this difference. It is a well- 

 recognized fact that the two ova are 

 distinct, and that twins may be unlike 

 in very many respects. 



tl 



it. 



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fiwrnii-^ 



!i icinalc adcclcd oT ' 



\>I\l UOIK. FAMILY IDIOCY 



'I1u" :il)()Vo t-hart shows tlu' amrstry of a 

 case of amaurotic family idiocy from 

 Falkcnlicim. Tlic hand points to the pa- 

 tient. 'IMic numerals in circles represent 

 number of chiMren whose sex was un- 

 known. (Fig. U)-) 



