i8o Journal of Comparative Neurology. 



are spread out on peculiar bundles of tendon fasciculi, which 

 are sharply differentiated from the surrounding tendon fasciculi 

 by reason of the fact that they are smaller, stain much more 

 deeply with alum carmine and show large numbers of round, 

 oval or oblong nuclei, which also stain deeply red in alum car- 

 mine, even in preparations in which the ordinary tendon nuclei 

 are not at all stained. The tendon on which the nerve ending 

 is found partakes, in other words, of the character of embry- 

 onic tendon. We see also in longitudinal sections that the vari- 

 cose fibers described either He on the surface of the tendon fas- 

 ciculi in long, undulating lines, or twine about or between them 

 in long serpentine windings, while the cross sections show es- 

 pecially well that the fibers penetrate these fasciculi and termi- 

 nate, usually with no enlargement, on the smaller bundles of 

 which the primary fasciculi are composed. We see also in 

 cross sections, as in Plate XIII, Fig. 4, that, sharply as the ten- 

 don bundles are differentiated from surrounding tendon and 

 compact and complicated as the whole ending often appears, 

 there seems to us to be no indication of a connective tissue 

 capsule surrounding the fasciculi and holding them together. 

 The nerve ending in frog's tendon is, as has been stated by 

 Cattaneo, Ciaccio, Smirnow and others, a free ending. 



As stated in the introduction, many of our preparations, 

 after staining in methylen-blue, were fixed in ammonium picrate 

 and cleared, teased and mounted in glycerine ammonium pi- 

 crate. This fixative softens somewhat the tendon and connect- 

 ive tissue and the whole ending is readily flattened out. While 

 this, it seems to us, is an advantage in studying the final termi- 

 nations of the nerve fibers, their size, shape and relation to the 

 main nerve fibers, yet it sometimes gives a rather false idea of 

 the end-organ and the relation of the nerve ending to the ten- 

 don fasciculi of the organ, unless this idea is corrected by com- 

 parison with preparations fixed in ammonium molybdate and 

 either cleared and teased in xylol and mounted in balsam, or 

 sectioned longitudinally. This fact can be readily substantiated 

 by a comparison of Figs, i and 2 of Plate XIII, which are sur- 

 face preparations, teased out of the glycerine-ammonium picrate 



