MOVEMENTS OF VOLUNTARY MUSCLE. 
501 
Fig. 88. Shows four stages illustrative of contraction, seen on one occasion in a 
primitive fasciculus of a Skate. The first state is that of rest; in the 
second, the striae on one margin are approximated in sets, the contrac- 
tions at the same time moving onwards. In the third state, the contrac- 
tions implicate the whole breadth of the fasciculus, and still advance. In 
the fourth state, the striae are everywhere approximated, the fasciculus is 
more opake and thrown into close rugae. The existence of these rugae is 
an accidental circumstance, resulting from the contraction of neighbour- 
ing fasciculi (not represented in the figure) drawing the ends of this one 
nearer together than they are brought by its own contraction. 
Fig. 89. Margin of a large fasciculus from a young Crab, in water, showing the 
first stage of contraction. 
