216 CHARLES R. STOCKARD 



smaller component represented by a malformed partial body, 

 attached to or protruding from it. 



The cause of doubleness and twinning in these human speci- 

 mens is in all probability the same as in the other cases dis- 

 cussed. The rate of development of the egg was probably 

 arrested during an early stage, and perhaps on account of some 

 interference or delay in implantation on the uterus. Very 

 recently I have obtained a specimen through the kindness of 

 Dr. Frank Erdwurm, of New York, which is of great value in 

 an understanding of twin development in man. 



The specimen secured by Doctor Erdwurm is shown by photo- 

 graph in plate 5. A living female baby weighing 6| pounds was 

 enclosed within the upper membranes seen in the photograph. 

 The cord from this baby is connected to the upper placenta near 

 its lower border. After delivering the child, a second chorionic 

 sac ruptured and discharged its fluid to the surprise of the 

 observer. Later the two dead fetuses seen in the picture were 

 delivered along with the placental mass. The fetuses proved 

 to be identical twin girls enclosed within a common chorion and 

 attached by their cords to a common placenta. The photograph 

 clearly shows the single membranous sac in which they were 

 enclosed and the positions of attachment of their cords to the 

 placenta. 



The size and other conditions of the fetuses indicate a stage 

 of about six months' development. They had evidently been 

 dead for a long time, probably about three months. The heads 

 and bodies were somewhat macerated and shriveled and the 

 blood-vessels had broken down in their placenta so that this no 

 longer had any circulatory communication with the uterus. 

 The two umbilical cords had become so wound around each other 

 and knotted, as to completely cut off the connection of the fetal 

 bodies with the placental circulation. The two fetuses were no 

 doubt asphyxiated after six months of development. 



This structural evidence is substantiated by the behavior of 

 the mother. She had passed through the first six months of 

 pregnancy in a normal fashion and then became greatly dis- 

 turbed, so that it was feared that her pregnancy might be inter- 



