62 
MAMMALIAN ANATOMY 
3. Teased preparations of nerve fibers which were stained, 
while fresh, with osmic acid (which blackens the medullary 
sheath), and subsequently mounted either in glycerine or 
in Canada balsam (Lab. SI. Coll.). Note in addition to the 
above described features, the numerous oblique incisions in the 
medullary sheath. 
4. Cross sections of nerve fibers, stained with haematoxylin 
(Lab. SI. Coll.). In case these sections include the whole nerve, 
note the connective tissue sheath of the nerve as a whole, the 
perineurium, and the more delicate sheaths of the component 
bundles, the endoneurium. 
5. Cross sections of nerve fibers which were previously treated, 
while fresh, with osmic acid (Lab. SI. Coll.). 
C. NERVE ENDINGS (Lab. SI. Coll.). 
1. Motor Nerve Endings. 
Motor End Plates in Muscle Fibers. —Note the deeply stained 
axis cylinders of the bundles of fibers which enter the muscle mass; 
follow single fibers to their terminations in flat discs (end plates) 
one of which is applied to each muscle fiber. Note whether a 
single nerve fiber ever divides and supplies more than one muscle 
fiber. Draw. 
Study a single disc with great care under the high power. 
Note that the axis cylinder of the nerve fiber breaks up into a 
network or reticulum to form the disc. Draw details to show 
these points. 
2. Sensory Nerve Endings. 
Muscle Spindles, in Muscle Fibers. — Note that each spin¬ 
dle is differentiated from portions of several muscle fibers. Work 
out with care under the high power, the relation of the nerve fibers 
to the muscle spindle. Draw a single spindle showing details. 
Pacinian Corpuscles, in the Areolar Tissue of Mesentery or of 
the Pancreas of the Cat. —Note that the end of the nerve fiber is 
covered by numerous concentric wrappings of connective tissue, 
which serve as a mechanical means for transmitting stimuli to 
the nerve ending. Select slides in which the Pacinian corpuscle 
may be seen cut transversely and study the arrangement of these 
