130 PRACTICAL HISTOLOGY [XVI 



The two, three or more small muscle fibres running through 

 the spindle ; in the mid-part of the spindle (equatorial region) 

 they have more nuclei than elsewhere. 



The one or more large or medium medullated fibres penetrating 

 the membranes of the spindle dividing amongst the muscle fibres, 

 becoming non-medullated and forming nerve-endings on the 

 fibres. 



The nerve-endings vary considerably in different mammals and in 

 different muscles, the two chief types are (a) the annulo-spiral, 

 consisting of flat bands partially encircling, or wholly encircling, or 

 surrounding in a spiral, the muscle fibres, and (/S) the flowered ending, 

 like an end plate, but larger and more irregular, and with many 

 terminal flat expansions. These two often occur in the same spindle. 

 In addition there may be near the end of the spindle, nerve-endings, 

 arising from small medullated fibres, closely resembling small end 

 plates. 



In the preparation of snake's muscle ( 6) muscle spindles will 

 probably be seen ; the spindle consists of a single muscle fibre, the 

 connective tissue membranes are comparatively little developed, so 

 that there is but little swelling in the equatorial region. The sensory 

 nerve-endings stain less readily than the motor nerve-endings; the 

 form is intermediate between the annulo-spiral and flowered ending. 



DEMONSTRATIONS. 



1. Transverse section of neuro-muscular spindle. 



2. Neuro-tendinous organ of cat or dog. 



NOTES. 



The methods of staining nerve-endings in muscle with gold 

 chloride and methylene blue are like those used for nerve-endings 

 in other tissues (cp. App. pp. 318 and 321). The muscle after 

 staining with gold chloride may be soaked in gum and cut with 

 the freezing microtome ; when looking for muscle spindles the 

 sections should be rather thick, even then a considerable number 

 of sections may have to be examined before finding one. 



