MOTOR NERVE-ENDING IQI 



known in working out the fiber details of ganglion structure. The 

 second, or methylene-blue method is used more to follow the fiber 

 courses near the periphery and the nerve elements in the sense organs. 

 Both methods are capricious in their results and can be made to suc- 

 ceed only by constant effort and as the result of experience. One must 

 be prepared to have them fail one time after another and yet to expect 

 good results the next time. No one of the numerous variations will be 

 set out at length here, but the student must have the individual direc- 

 tion of an instructor and work up the particular modifications that 

 he finds most satisfactory from among the many that are described 

 in LEE'S " Microscopist's Vade Mecum." 



LITERATURE 



Besides the parts devoted to the nerve fiber in Schneider's, Barker's, and other text- 

 books, it is enlightening to read the following : 



HARRISON, R. G. "Observations on the Living Developing Nerve Fiber," Proc. of the 

 Soc. for Experimental Biology and Medicine, 1907, pp. 140-143. 



NEAL, H. V. The "Development of the Ventral Nerves in Selachii," Mark Ann. Vol- 

 ume, 1903. 



APATHY, S. " Das leitende Element des Nervensystems und seine Beziehungen zu den 

 Zellen," Mitt. a. d. Zool. Sta. zu Neapel, Vol. XII, 1897, p. 495. 



BARDEEN, C. R. "The Growth and Histogenesis of the Cerebro-spinal Nerves in Mam- 

 mals," Am. Journ. of Anal., 1902, Vol. XI, p. 231. 



RETZIUS, G. "Was ist die Henlesche Sch^de der Nervenfasern?" Anat. Am., Band XV. 



WYNN, W. H. "The Minute Structure of the Medullary Sheath of Nerve Fibers," Jour- 

 nal of Anatomy and Physiology, Vol. XXXIV. 



THE MOTOR END-ORGANS OF NERVE CELLS 



By motor end-organ is meant the modification of the end of the effer- 

 ent process of a nerve cell which enables it to transfer or discharge its 

 impulse as a stimulus to another nerve cell or to a muscle cell, an electric 

 cell, or a gland secreting cell. Such an impulse is used to discharge the 

 secretion material or to cause it to be used in situ. 



While differing to some degree in size and complexity among them- 

 selves, the several kinds of motor end -organs do not present the great 

 variety of form and adaptation that the end-organs on the other or per- 

 ceptory pole of the nerve cell do. Nor can we distinguish any specific 

 cell-organs pertaining to the particular function of each of the organs 

 as we can in the perceptory endings, especially those that are situated in 

 the periphery. 



As in the perceptory ending, the motor endings may be placed directly 

 on the nerve-cell body or removed from it to the end of one of its 

 processes, the efferent fiber. Like the fiber, it is an integral part of the 

 cell, a direct continuation of the fiber itself. The exact relations of the 



