150 
ADAM SEDGWICK. 
The tubules of the Wolffian body do not develop from 
serial involutions of the peritoneal epithelium, but from the 
cells of the intermediate cell mass. The intermediate cell 
mass is so familiar to all students of Avian embryology that 
Fig. 1.’ — Section from a chick of the second day, showing the inter- 
mediate cell-mass. M. c. Medullary canal. P.v. Protovertebra. 
}F. d. Wolffian duct. p.p. Body-cavity, c. h. Notochord, a. o. aorta. 
1 For the woodcuts, figs. 1 and 2, I have to thank Mr. Balfour. Fig. 1 
is from the * Elements of Embryology.’ 
