The Microscope. 233 



Tapering fibers are generally one-half to two-thirds the length 

 of the muscle in which they occur, the length relatively to the 

 muscle being much greater than in the larger animals. 



The average diameter of the fibers at full size is generally about 

 30 /" to 70 /', which corresponds closely with the number given for 

 man. 



In the limb and trunk muscles and those ending in corium, the 

 tendinous end, the body of the fiber and the intramuscular end may 

 be simple or may branch. In the larger animals isolated cases of 

 branching, intramuscular ends have been shown, while in many 

 animals, the endings in corium for a long time have been known to 

 branch. Hence the generally accepted idea that a muscular fiber is 

 unbranched from end to end is untenable. 



EXPLANATION OF THE PLATES. 



The drawings were made from the specimens with Abbe's 

 camera-lucida. Except when otherwise specified, Zeiss' 8 mm. 

 apochromatic objective and compensation ocular x 4 were used, but 

 some of the details were determined by the Zeiss' 2 mm. apochro- 

 matic, homogeneous immersion objective. 



The specimens are from muscles dissociated i7i situ in nitric 

 acid, except when otherwise stated in the description of the figures 



The intermediate part of the fiber marked b should be greatly 

 elongated, 40 to 100 times, in order to give a correct idea of the 

 form of the fiber. In the plates the comparative size of the fibers 

 is graphically represented. In the limb and trunk muscles of the 

 mouse, Fig. Qt is of the average size of a fiber. Fig. 9b is a small fiber, 

 while a very large fiber is twice as large as Fig. 13^. In the skin of 

 the mouse the average lies between b and h, Fig 7. That in the 

 tongue is shown in Fig. 286, in the oesophagus in Fig. 246. The 

 average in the limb and trunk muscles of the shrew is shown in Fig. 

 146, of the bat in Fig. 46, of the English sparrow in Fig. 5/i. 



PLATE VIII. 



Magnification, 260 diameters. 



Figs. 1 to 9. — These figures give a diagrammatic view of the 

 form and arrangement of the fibers in the longer muscles of the 

 mouse. Fig. 1 is of a fiber which extends from tendon to tendon. 

 Figs. 2-8 are of tapering fibers with tendinous ends at opposite 

 tendons and intramuscular ends at different relative distances from 

 the tendons. Fig. 9 is of a spindle-shaped fiber with both ends 

 intramuscular. 



