ON THE FREQUENCY OF LOCALIZED ANOMALIES IN 

 HUMAN EMBRYOS AND INFANTS AT BIRTH 



FRANKLIN P. MALL 



EIGHTEEN' riGTRES 



111 a paper published nine years ago on the causes underlying 

 the origin of human monsters, I made the assertion that local- 

 ized anomalies were more common in embryos obtained from 

 abortions than in the full term fetus, without, however, adduc- 

 ing conclusive evidence in support of this theory. ^ 



In a footnote on page 27 of that publication I gave a list of 

 embryos with their chief defects, comparing them ^\dth the 

 percentage of frequency of monsters born at full term. An 

 objection to be raised to such a statement is the fact that there 

 is not a complete correspondence between anomalies in the 

 embryo and those found in the fetus at the end of pregnancy. 

 For instance, spina bifida in young embryos is always complete 

 while at full term the open canal is covered over with skin. 

 Cyclopia and exomphaly are the same in the embryo as at 

 birth, but the deformities of the head and neck of the embryo 

 are of such a nature that it cannot live long enough to admit 

 of comparison with like malformations found at term. With 

 these difficulties clearly before me, I have made an effort to 

 define sharply the anomalies in embryos, so that a satisfactory 

 comparison might be made with those found in monsters at the 

 end of pregnancy, as described in the literature. 



I shall mention first cyclopia, for it seems to me that it is 

 the type of monster which is now best understood. This clearer 

 conception is due largely to the excellent experimental work of 

 Stockard, and partly to the fact that the cj^clopean state can 

 exist quite independently of other marked deformities of the 



^ Mall, F. P. A study of the causes underlj^ing the origin of human monsters. 

 Jour. Morph., vol. 19, 1908. 



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THE AMERICAN JOUnXAL OF ANATOMY, VOL. 22, NO. 1 



