JOURNAL OF MICROSCOPICAL SCIENCE. 
EXPLANATION OF PLATES XVII AND XVIII, 
Illustrating Mr. Sedgwick^s Memoir on Development of 
the Kidney in its Relation to the Wolffian Body in the 
Chick.^^ 
Complete List of Reference Letters. 
Ao. Aorta. At. Alimentary canal, cl. Cloaca, c. v. Cardinal vein. 
ep. Epiblast. hp. Hypoblast, i. c. m. Intermediate cell mass. i. c. mJ 
Cell mass, which later becomes the intermediate cell mass. m. e. 
Mesentery. M. d. Mullerian duct. k. b. Kidney blastema. k. t. 
Kidney tubule, n. c. Notochord, p. Protovertebra. p' . Cell mass, 
which later becomes a protovertebra, p. v. Body-cavity, p. e. Peri- 
toneal epithelium. t. Testis. u. Ureter. ve. Vertebral body. w. 
Wolffian body. w. b. Wolffian blastema, w. d. Wolffian duct. w. t} 
Primary Wolffian tubule, w. t? Secondary ditto, w. t? Tertiary ditto. 
Fig. 1. — Section between the fifteenth and sixteenth protovertebrse 
of a chick with twenty-three protovertebrae, showing the rudimentary 
continuation of the body-cavity into the intermediate cell mass and the 
connection which the latter has obtained with the Wolffian duct. The 
intermediate cell mass in anterior and posterior neighbouring sections 
has separated from the peritoneal epithelium. 
Figs. 2, 3, 4, and 5. — Sections taken from a duck embryo with about 
thirty-two protovertebrae, illustrating the development of the Wolffian 
tubules. Hart, cam., ob. 4. 
Fig. 2. — Section through the thirtieth segment, intermediate cell mass 
continuous with peritoneal epithelium, and containing a rudimentary 
prolongation of the body-cavity. Lumen of Wolffian duct doubtful. 
Fig. 3. — Section through the twenty-ninth segment, intermediate 
cell mass separate from peritoneal epithelium. 
Fig. 4. — Section through the twenty-sixth protovertebra, showing 
features similar to above. 
Fig. 5. — Section through the twenty-second protovertebra ; eom- 
mencing diflferentiation of Wolffian tubule. 
Figs. 6 — 10. — Sections illustrating the more modified development^of 
the Wolffian blastema, as seen in the chick behind the twentieth segment. 
Fig. 6. — Section through a chick with twenty-six protovertebrae 
behind the four last-formed segment, showing the thick peritoneal 
epithelium, the Wolffian blastema in connection with the mass of cells 
which will become a protovertebra. Hart, cam., ob. 4. 
Fig. 7. — Section through the twenty-ninth protovertebra of a chick 
with twenty-nine protovertebrse, showing the thick peritoneal epi- 
thelium and the Wolffian blastema in connection with the provertebrai. 
Hart, cam., ob. 4. 
Fig. 8. — Section through the twenty-fourth segment of a chick with 
twenty-six protovertebrm, showing the Wolflian blastema separate from 
protovertebrm and thick jieritoneal epithelium. Hart, cam., ob. 3. 
