DEPARTMENT OF EMBRYOLOGY. 



George L. Streeter, Acting Director. 



At the outset of the current year the Department of Embryology 

 suffered an irreparable loss through the death of its Director, Professor 

 Franklin P. Mall, on November 17, 1917. Owing to his wide influence 

 in the development of scientific medicine and medical education, this 

 great blow is not limited to our department alone, but also deeply 

 concerns the medical profession at large, and particularly all those 

 who are interested in the advancement of the science of human em- 

 bryology. 



At the time of his death Dr. Mall was engaged in the preparation 

 of two papers; one, a monograph on the implantation of the human 

 ovum, which was being prepared in cooperation with Dr. J. Whitridge 

 Williams, who has undertaken the completion of the study; the other, 

 an analytical survey of all the pathological ova in the Carnegie Em- 

 bryological Collection. This was to be a joint paper with Professor 

 Arthur W. Meyer. The plan of the study had been definitely laid 

 out and the work had advanced far enough to enable Professor Meyer 

 to continue it without interruption. It is now nearly completed. 



Since the last report two studies by Dr. Mall have been published. 

 One of these concerns the frequency of localized anomalies in human 

 embryos and infants at birth. An embryo normal in form, even 

 though it be surrounded by diseased or deformed membranes, is 

 classed by him as normal, on the theory that the pathological condi- 

 tions under which it may have developed were not sufficiently serious 

 to produce any change in the embryo. If the latter is normal in 

 all but one respect it is termed normal with a localized anomaly. As 

 far as can be determined, such an embryo would have survived but 

 for the factor that caused the expulsion of its membranes. It is from 

 this group that one might expect monsters at term. 



The pathological embryos show a variety of changes ranging from 

 macerated fetus and fetus compressus to complete disintegration of 

 the ovum, where only a few villi are left. These are segregated by Dr. 

 Mall into seven groups according to the severity of the process. Tables 

 covering the first 1,000 specimens in the collection show that 396 

 (nearly 40 per cent) are pathological, of which 31 per cent are uterine 

 and 9 per cent ectopic. Localized anomalies were present in 10 per 

 cent of the pathological embryos, while in the normal group they 

 occurred in 6 per cent of the cases. All of the pathological specimens, 

 whether with or without localized anomalies, were aborted during the 

 first half of pregnancy. Specimens belonging in the normal group 

 usually fall within the first five months, but older ones are occasionally 

 met with, there being one in the sixth, one in the eighth, and five in 



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