A HUMAN EMBRYO OF TWENTY-FOUR PAIRS OF SOMITES, 



BY FRANKLIN PARADISE JOHNSON. 



INTRODUCTION. 



The embryo herein' described was received February 9, 1914, from Dr. W. L. 

 Allee, of Eldon, Missouri. Accompanying the specimen was a letter with the 

 following information, but no further data regarding its history are obtainable: 



The patient menstruated January 20 to January 25. Menstrual flow recommenced 

 February 2, but it was freer and brighter in color than usual. On February 7 the speci- 

 men was aborted. Less than five minutes after abortion it was placed in 10 per cent 

 formalin, in which fluid it was sent to me. 



Fni. 1. Drawing showing pusitinn of cmlnyo in Hinrionic vc-M-lr. Si-ninn J5 

 (of embryo). Xlo diameters. 



The chorionic vesicle appeared as an elongated rounded body, of a cream 

 color and a very delicate texture. It measured 15 by 9 by 8 mm. Extending 

 from end to end of the vesicle, a flat fold with a slit in it was visible. It was 

 covered with villi everywhere except along the fold. For fear of ruining a valu- 

 able embryo no attempt was made to open the sac. The whole vesicle was run 



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