No. 3.] A HUMAN EMBRYO TWENTY-SIX DAYS OLD. 477 



forms a complete semicircle in the cervical region, larger but 

 more flat in the dorsal, and again somewhat smaller but semicir- 

 cular in the lumbar region. The Wolffian duct extends through- 

 out the body, extending just below the free surface and lying 

 on the dorsal side in the lumbar region and on the ventral side 

 in the cervical region. The glomeruli extend from the sixth 

 cervical nerve to the fifth lumbar, and there are about two or 

 three glomeruli to a segment. In the cervical region the tubule 

 connecting the glomerulus with the Wolffian duct is slightly 

 bent, in the dorsal region greatly convoluted, and in the lumbar 

 region it is straight. 



Clark University, Worcester, Mass., 

 May 14, 1891. 



