Fig. 21. 
Fig. 22. 
BREED. — Muscle Metamorphosis. 
mee 
. 16. 
PLATE 6. 
Posterior face of lateral (right) portion o- cross section of the meta- 
thorax of an zmago showing the parts affected by the contraction of 
musculus episternalis (e’stn.). > 160. 
Cross section of the largest fibre of musculus metanoti. Drawn from a 
resting larva about midway in its development.  X 800. 
Cross section of that portion of musculus metanoti which has been de- 
rived from the largest fibre of this muscle in the larva. Drawn from 
an imago. Compare Fig. 14. X 800. 
Cross section of a functional larval muscle fibre. Feeding larva. X 800. 
Longitudinal section of a fibre of retractor mesothoracis inferior. Drawn 
from an imago. X 1600. 
Cross section of a fibre of flexor alae metathoracis secundus drawn from 
the same series of sections. X 1600. 
Cross section of flexor coxae metathoracis secundus. Drawn from a 
young pupa. X 800. 
Cross section of a circular muscle fibre of the foreintestine of an zmago. 
x 1600. 
Cross section of three fibres of flexor coxae metathoracis secundus. 
Taken from an old pupa. Compare Fig. 19. xX 800. 
Cross section of a functional larval muscle fibre. Feeding larva. XX 800. 
Figs. 23-32. Of these figures, Figs. 23-25, 30 and 31 form a series of longitudinal 
Fig. 
Fig. 
Fig 
> 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
23. 
24. 
25. 
26. 
Pal 
28. 
29. 
30. 
ol. 
32. 
sections, and Figs. 26-29 and 32 a series of cross sections, of small por- 
tions of muscle fibres of the wing type. These drawings illustrate the 
changes in the finer structure of these muscles during their metamor- 
phosis. All of the figures are magnified 1600 diameters. 
Feeding larva. Longitudinal section of part of a functional fibre. 
Restinglarva. Longitudinal section of part of musculus metanoti. 
Resting larva a few hours before pupation. Longitudinal section of part 
of musculus lateralis metathoracis anterior. 
Feeding larva. Cross section of part of a functional fibre. 
Resting larva. Cross section of part of flexor coxae metathoracis 
secundus. 
Resting larva a few hours before pupation. Cross section of part of mus- 
culus metanoti. 
Midway pupa. Cross section of part of musculus lateralis metathoracis 
posterior. 
Midway pupa. Longitudinal section of part of musculus metanoti. 
Young imago. Longitudinal section of part of musculus metanoti. 
Old pupa. Cross section of part of extensor alae metathoracis. 
