A STUDY OF THE SUPERIOR OLIVK, 



BY GEORGE B. JENKINS. 



Some years ago, while working under the stimulating influence of Dr. Mall, 

 I undertook at his suggestion the study of the morphology of the human inferior 

 olive. During the progress of that work I determined to extend the investigation 

 to include a detailed study of all the cell collections in the brain stem, both in man 

 and in such of the lower animals as might be available. I now wish to present 

 some of the results of this study as applying to the so-called superior olive, the 

 literature upon which subject is so contradictory and confusing that one gets but 

 a vague idea of this nuclear mass. 



It seems probable, from a study of the earlier literature, that the term olirc 

 was applied to the inferior or bulbar olive because of the presence of the oval or 

 olive-shaped prominence upon the exterior of the ventro-lateral surface of the 

 medulla; and that later, when the underlying nucleus was discovered, it was quite 

 naturally termed the olivary nucleus. The only apparent reason for calling the 

 smaller pontine nucleus the superior olive was the assumption that it was related 

 to and of similar cell content as the earlier-discovered inferior body. Neither of 

 these conclusions has been borne out by my findings. 



In order to arrive at a clearer comprehension of the superior olive, it was 

 determined to use cat tissue for a preliminary study, since all investigators seem 

 to agree that this animal has a large and beautifully developed nucleus. A number 

 of other animals, including dogs, rabbits, field-mice, rats, and ground-squirrels, 

 were used as checks, and all findings were compared with human tissue of varying 

 ages. As a result of these studies the more representative types were found to be 

 the cat, dog, and man. The tissue figured herein consists of the brain-stem of an 

 adult cat, serial No. Fel. 1, cut in transverse sections 20 microns thick and stained 

 with hematoxylin and eosin; the brain of a dog-fetus, 115 mm., serial No. Can. 1, 

 cut in transverse sections 20 microns thick and stained in Ehrlich's hematoxylin ; 

 the brain-stem of an adult dog, serial No. Can. 4, cut in transverse sections 20 

 microns thick and stained in hematoxylin and eosin; the brain-stem of a human 

 fetus 168 mm. (CR), serial No. Hu. 28, cut in transverse sections 20 microns thick 

 and stained with borax carmine and Lyons blue. All were reconstructed by the 

 Born method, using 2-mm. wax plates. All of the sections of the human specimen 

 were drawn at a magnification of 100 diameters; in the dog and cat specimens 

 every alternate section was drawn at 50 diameters. The adult dog was not modeled, 

 since the outlines of the nuclear masses in the two animals are identical in all 

 essential particulars; and, owing to the comparative scarcity of associated fibers and 

 the simplicity of the cell components, the younger animal offered fewer mechanical 



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