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STUDIES ON PATHOLOGIC OVA. 



far more reliable data, because the variations in thickness of the membranes are 

 slight and one has then to contend only with the question of distention from hy- 

 dramnios or other causes. 



Since the curve is fairly regular throughout, and the disproportion of the 

 cases but slightly greater as the older conceptuses are reached, I think it can be 

 assumed that it is approximately correct in its general relations. With advancing 

 age it is seen that the length of the fetus more and more approximates the greatest 

 dimension of the chorionic vesicle. This is in agreement with common observa- 

 tion and shows that the greatest chorionic dimension no longer can be of any 

 special value for determining the fetal age. Moreover, in older conceptuses the 

 vesicle no longer retains its form. 



Since the majority of the tubal specimens fall considerably below the curve, 

 it is evident that development of the fetus was considerably retarded in these 

 specimens. Only a few fall above the curve, but one of these is so very far. above 

 that one is compelled to conclude that the greatest dimension of the chorion was 

 not obtained in this case, or the chorionic vesicle must have been torn and the 

 amniotic fluid drained off. As will be noticed, the length of the fetus in this case 

 exceeds that of the membranes in which it was contained. 



From the curve it is seen that the relations apparently existing between the 

 chorionic and cyemic dimensions are approximately those shown in table 6. 



TABLE 5. (From Evans.) 



TABLE 6. 



A comparison of the estimates on the accompanying graph (Chart 1) with 

 the estimates of other investigators previously referred to shows that those of 

 Evans agree most closely with these. However, the present curve can be regarded 

 as provisional only, for it is based upon but 255 cases and upon external measure- 

 ments alone. 



