VI. HISTOLOGY OF MUSCLE TISSUE 
A. SMOOTH OR UNSTRIATED INVOLUNTARY MUSCLE. 
1. Tease on a slide a few shreds from a portion of the muscular 
coat of the intestine of a cat or other mammal (fresh material), 
which has macerated for 48 hours in 20% nitric acid. Add 
glycerine and cover. Study the preparation with the compound 
microscope, and note that each muscle fiber consists of a single 
elongated, spindle-shaped cell with one granular, elongated nucleus, 
. and with numerous fibrils extending lengthwise through the cyto¬ 
plasm. Draw a jew well-selected examples. 
2. Study transverse sections (Lab. SI. Coll.) through the small 
intestine of Necturus or other amphibian. Note that the mus¬ 
cular coats, both circular and longitudinal, are composed of smooth 
muscle cells closely packed together with their long axes parallel 
to each other. Draw a detail showing a longitudinal section of a 
few adjacent cells (from the circular coat), and one showing a jew 
cells in cross section (from the longitudinal coat). 
B. STRIATED VOLUNTARY MUSCLE. 
From your study of all the following preparations note that a 
striated or voluntary muscle fiber consists of a long, cylindrical, 
multinucleate structure, or syncytium, enclosed in a delicate 
membrane, the sarcolemma, and ending at each end in the case of 
vertebrates in a conical attachment to a bundle of tendon fibers. 
Within the sarcolemma and visible only with high power, are 
innumerable minute fibrils, extending throughout the entire 
length of the fiber and exhibiting minute cross striations. These 
are the contractile elements of the liber, and their cross striations, 
visible en masse even under low power, give the fiber as a whole its 
cross-striated appearance. Note whether nuclei are scattered 
throughout the thickness of each fiber or lie only immediately 
beneath the sarcolemma (cf. rabbit and Necturus in this regard). 
1. Tease in a drop of normal salt solution on a slide, a few 
shreds of voluntary muscle from a recently killed animal, for 
50 
