30 H. E. JORDAN 
are pale medially and darker staining and knobbed terminally. 
There is obviously going on a transfer of deeply staining substance 
from the middle of Q toward the middle of J. This process is 
earried still further in the fiber of figure 19, where relatively 
pale thick contraction bands have formed. This stage corre- 
sponds to the so-called homogeneous phase of contraction ofcertain 
writers. The thick, pale, early contraction bands condense 
into the typical definitive thin deeply staining contraction 
bands of the fully contracted fiber (fig. 20). These same steps 
are shown in longitudinal series within four sarcomeres in figure 
10, drawn from a preparation of leg-muscle fiber of the grass- 
hopper. 
Figure 16 is given to illustrate the character and distribution 
of the nuclei. This fiber is in the relaxed condition and only 
lightly stained. The nuclei are centrally placed (fig. 17) and are 
larger and smaller spheroidal bodies, with a delicate reticulum 
and relatively large, irregular, very chromatic net-knots. The 
nuclei occur arranged in long axial columns; indeed, in certain 
fibers they seem to occupy the core of the entire fiber. Where 
they occur in shorter groups, the terminal nuclei appear to be 
smaller than those more medially placed. Occasionally a regular 
progressive decrease in size occurs in both directions from the 
middle to the terminals of the group (fig. 16). No mitotic 
figures were seen. Nuclear multiplication is here exclusively 
by the amitotic mode. Cross-sections (fig. 17) show that the 
fibers are of irregular cylindric form, and that the myofibrils 
(sarcostyles) are of the lamellar type. These lamellar sarco- 
styles occasionally show a peripheral radial splitting, giving rise 
to Y-shaped sarcostyles as seen in transverse section. 
b. Wing muscle 
The wing muscle differs markedly from the leg muscle. It 
consists of robust fibers, of irregular polygonal form in trans- 
verse section (fig. 11). The fibers are enveloped by a delicate 
sarcolemma. An occasional nucleus is peripherally placed, the 
majority are scattered indiscriminately throughout the fiber. 
The nuclei are small oval bodies and are very chromatic; in 
