ARTHUR F. COCA 



1005 



Table I (taken from the article by Spain and Cooke) shows the incidence of the 

 two atopic conditions in the offspring under the three categories of hereditary influ- 

 ence. It is seen that, under a bilateral influence, nearly 70 per cent of the offspring 

 were destined to be affected. This figure approximates the percentage (75) that 

 should be expected if the condition is dependent upon a single Mendelian dominant 

 factor, both parents being assumed to be hybrid with respect to it. The percentage 

 incidence found under a unilateral influence approximates the expectation (50 per 

 cent) on the assumption just mentioned. 



In discussing the considerable percentage (about 40) of atopic individuals with 

 negative family history, Spain and Cooke call attention to the fact that these indi- 

 viduals were practically "self-selected from among 11,500 individuals of the general 



TABLE I 



Showing the Percentage of Atopic Children Estimated to Develop 

 IN THE Three Classes* 



Inheritance 



Bilateral: 



Present findings 



Cooke and Vander Veer . 



Combined findings 



Unilateral: 



Present findings 



Cooke and Vander Veer . 



Combined findings 



Negative : 



Present findings 



Cooke and Vander Veer . 



Combined findings 



32 

 26 

 S8 



52 

 263 



228 



►J H 



83 

 70 



666 



ISO 

 816 



289 

 631 

 920 



Atopic 

 Children 



Number 



5° 

 39 



321 



77 



398 



104 

 205 

 309 



Per Cent 



of 



Total 



60. 2 

 55-7 



58.0 

 48.2 



51-3 

 49.8 



35 9 

 32.4 

 34- 1 



16. 



23- 



19- 



33- 



27. 



30- 



32. 



35- 

 33- 



2 < 



Estimated Atopic 

 Children 



Number 



59 S 



47.2 



106.6 



373-8 



91. 2 



460. 1 



126.0 

 244.0 

 370.0 



Per Cent 



of 



Total 



71 .6 

 67-5 

 69 -5 



56.1 

 60.0 

 58.0 



43-6 

 38.6 

 41. 1 



* From Spain and Cooke. 



population." In other words, it would not be permissible to consider the ancestry of 

 this group free from the atopic character, unless 11,500 antecedents had been acces- 

 sible for examination in this regard — an impossible requirement. However, this idea 

 does not explain why a single dominant character should so often be missing in both 

 parents of the child that exhibits it; and, furthermore, the assumption of a single 

 dominant factor does not easily explain the differences of degree in the inheritance 

 that are revealed in the hereditary influence upon the age of onset. 



The influence of heredity upon the age of onset of atopic hypersensitiveness is 

 seen in the characteristic difference in the graphic representation of this feature as it 

 is found under the three categories of atopic inheritance. The three curves plotted by 

 Cooke and Vander Veer and Spain and Cooke, in their study of nearly one thousand 

 cases, are so evidently characteristic that one can doubt the hereditary control of the 

 age of onset only by assuming a gross error in the assembling of the data. These dif- 

 ferences can be expressed in part by noting that, by the tenth year of life, atopic 



