194 Journal of Comparative Neurology. 



either medullated or non-medullated nerves, so that the typical 

 arborization effect is nearly lost. We have observed this type 

 of end-organ in none of the other animals studied. 



While the general structure of the neuro-tendinous end- 

 organs and the general arrangement of nerves in the organ are 

 the same for all mammalia studied by us, the terminal nerve 

 apparatus differs somewhat in the different animals and is quite 

 characteristic for each species. We will therefore describe the 

 nerve end-plaque for the different forms somewhat in detail. 



In the dog, as stated above, long medullated nerves pass 

 through the organ almost unbranched, lose their sheath of 

 myelin, but as still rather large and nearly unbranched axis 

 cyhnders pass toward the extremity of the organ and either 

 end unbranched in a terminal granular enlargement, round or 

 pear-shaped, or irregular expansions of the axis cylinders, or 

 branch into a number of varicose fibers, fine axis cylinders, on 

 which are seen numerous round, oval, pear-shaped, irregularly 

 polygonal or leaf-like enlargements, which may rest directly on 

 the fine nerve fiber or may be raised from it by a very fine 

 nerve filament in which case it resembles still more a leaf or 

 flower attached to a stem by a long, slender pedicle. At the 

 extremity of each non-medullated branch, as at the end of the 

 main nerve fiber, the axis cylinder widens out into the peculiar 

 granular enlargement characteristic of this ending in all its 

 forms. This terminal enlargement may be a simple round or 

 oval ball or the whole fiber may broaden out for a considerable 

 length, having thorn- or leaf- or plate-like masses attached to it, 

 at the sides, at the ends, in an irregular confused way, wherever 

 room can be found for one to lodge. The whole non-medul- 

 lated nerve may twine about and between the fasciculi in a ser- 

 pentine manner, penetrating the fasciculi, while the character- 

 istic enlargements clasp the bundles of tendon fibers composing 

 the fasciculi. In addition to the terminal arborization, all along 

 the long, large non-medullated fiber, short fine side branches 

 are given off, which end as do the parent fibers. Besides these, 

 many processes are given off from the main stem, of different 

 shapes, all granular, some with slender, short pedicles, support- 



