PLATE I—(continued). 
Fig. 
22.—Muscular fibres from the back and leg of a luman feetus, between the 
second and third month: @,a fibre in which the investing sarcous- 
substance has been formed more thickly on one side than on others. 
By this unequal growth the nuclei are left near the surface at dif- 
ferent parts of the fibre. J. A fibre undergoing contraction, and 
becoming more cylindrical and of more uniform structure ; on one 
of its sides are two nuclei joined by granular process, for the de- 
velopment of a new fibre; magnified 420 diameters. ¢, d, ef. 
Smaller fibres from the thigh, maguified 670 diameters; at e the 
transverse strie are very strongly marked; in the others are seen 
numerous large and dark granules. g Is a larger fibre from the 
same locality, magnified 670 diameters. 4. A small fibre from the 
same, in the first stage of formation; two nuclei are joined end- 
wise by a delicate granular substance, and give off tapering pro- 
longations of the same delicate substance from their opposite 
ends ; along one side of the wholea band or fibre has been formed ; 
magnified 420 diameters. 7. Another fibre from the same; at its 
lower part the lateral band or investing substance has increased 
in thickness, so that the axis is nearly obliterated, aud the fibre is 
of nearly uniform structure; the striations are also strongly 
marked. j. Two other fibres lying side by side; the larger has 
thick, lateral bands, divided into fine transverse striae, with a dis- 
tinct axis, which resembles the other younger fibre at its side; by 
altering the focus the whole surface of the fibre was found to be 
striated, as in the large fibre (g) in this figure, so that the axis is 
invested by a tube of striated substance. 
23.—Muscular fibres fram a human fcetus of four months. 
24.—Nucleated fibres of the tendon of a muscle of an arm of a human feetus 
two months: 4, as they are arranged 7 sifu; a, separated, and 
more highly magnified. 
