Boyer. — Mesoderm in Teleosts. 
. 
PLATE III. 
The embryos from which the drawings of this plate are made were killed with 
Perenyi’s fluid and stained with Kleinenberg’s haematoxylin. Figs. 17 and 18 are 
from an embryo of 79 hours. The sections are about 8 in thickness. Figs. 16 
and 19-22¢ were made from an embryo of about 76 hours. Sections are 7} @ in 
thickness. 
Figs. 16-18. TRANSVERSE SECTIONS. 
Fig. 16. Through the region of the auditory vesicle and fourth gill-pocket, show- 
ing right side. X 310. (See explanation of Fig. 19.) 
Fig. 17. Through the middle region of the first protovertebra, showing the left 
side. X 310. 
Fig. 18. Through the middle region of the second protovertebra, showing the 
right and left sides. X 510. 
Figs. 19-22%, SacGirrat Srecrions. 
Fig. 19. From the right side of the same embryo as Fig. 16. The anterior edge 
of the section in Fig. 19 joined the posterior (under) surface of the 
section shown in Fig. 16, and the planes of the two sections intersect 
each other at right angles. The vertical lines in Fig. 16 indicate the 
positions and direction of the planes of the sections shown in Figs. 
19-21, and are numbered correspondingly. X 175. 
Fig. 20. From the region indicated by the vertical line numbered 20 in Fig. 16. 
x 175. 
Fig. 21. From the region indicated by the vertical line numbered 27 in Fig. 16. 
ye LSE 
Fig. 22. Through the median plane of the chorda, in the posterior trunk region. 
< 310. The region embraced under A shows a portion of the 
chorda in which the cells are flattened, and the nuclei are conse- 
quently arranged in planes at right angles to the axis of the embryo. 
A’ (Fig. 22%) shows the anterior portion of this region, and A” em- 
braces the anterior end of the chorda, in which the nuclei are few, 
and have not yet arranged themselves in the vertical plane. 
Fig. 22%. Through the median plane of the chorda, showing the anterior end. This 
drawing is made from a part of the same section as Fig. 22. x 310. 
See also explanation of Fig. 22. 
