232 The Microscope. 



of the mouse, bat and sparrow, and in the obliquus abdominis of the 

 mouse. 



An extreme case of division at the tendinous end was found 

 in a short fiber, 4.5 mm. long, from a penniform muscle of the ante- 

 brachium of a mouse (Fig. 34). The division extends about 1.5 mm., 

 one-third the length of the fiber. 



For convenience, the large branched endings of fibers from the 

 skin and mucosa will be classified with the tendinous ends. Their 

 position at the end of the muscle, and their size in relation to the 

 body of the fiber to which they belong, give them a much closer 

 resemblance to the tendinous than to the intramuscular end of fibers 

 from limb and trunk muscles. In form, their resemblance to tendinous 

 ends can be seen by comparing Figs. 24, 31 and 33 with Figs. 6 and 

 32. Frequently, however, these ends become much expanded later- 

 ally (Figs. 27-30). They often have fine, hair-like and root-like 

 branches or processes (Fig. 27), which may be compared to those of 

 Fig. 4:t, and Fig. (St. These forms are similar to those figured by 

 Busk and Huxley in the skin of the rat's lip, to those described by 

 Kolliker, and figured by Biesiadecki and Herzig in the frog's tongue, 

 and to those figured by Margo from the alimentary canal of 

 invertebrates. 



9. Bkanching of Fibers at full size. — Besides the branching 

 already mentioned, there occurs occasionally in the limb and trunk 

 muscles of the mouse, bat and shrew, a more or less equal division of the 

 fiber at its full size into two parts. This is of frequent occurrence 

 in the fibers of the tongue and cesophagua of the mouse and bat 

 (Fig. 26). 



10. The fiber represented by Fig. 23 is a unique example, 

 showing a fiber which appears to be splitting longitudinally. The 

 clefts in the specimen have the clear outlines of a natural contour 

 and do not at all resemble artificial tears. A noteworthy feature of 

 this fiber is the longitudinal rows of nuclei, some of them dividing, 

 which extend fi'om the ends of the clefts. In works on development 

 of muscle it is frequently asked if fibers multiply in number by 

 longitudinal division. No valid conclusions could be drawn from 

 one example. 



SUMMARY. 



From the above it will be seen that in small animals muscular 

 fibers may extend from tendon to tendon, or one or both ends may 

 terminate within the muscle. The difference in this respect between 

 these and the larger animals is chiefly that in the latter there are 

 many more spindle-shaped fibers with both ends intramuscular. 



