126 JACUBOWITSCHj ON THE NERVOUS SYSTEM. 



consequently, as being the place Avheve new cells are conti- 

 nually formed and developed. With respect to the cones, I 

 regard them simply as axial cylinders of the optic nerves, 

 bent round so as to terminate in nerve-cells, and Avhich become 

 the more apparent and the longer in proportion as they pene- 

 trate more deeply into the inferior layers ; whence it arises 

 that their form and length are more or less variable. 



As regards the bacillar layer, it does not constitute an 

 essential part of the nervous elements, properly so termed, of 

 the retina ; but is rather to be regarded as belonging to the 

 pigment-cells, of which it is the direct continuation. In the 

 eyes of fish and of frogs it may be readily separated and 

 obtained in horizontal, lateral, and transverse sections. 



ly. In the heart, lunfjs, kidneys, and in the submucous 

 layer of the bladder and intestine, there may be distinctly and 

 clearly observed in the course of the nervous fasciculi groups 

 of nerve-cells, which, from their form, I take to be gan- 

 glionic cells; and in v,hich the axial cylinders may be 

 distinctly seen to terminate, not, in this case, in the nucleus 

 of the cell, but in the body of the cell altogether. 



Thus, in recapitulating the results of my researches on the 

 peripheral nervous system, I arrive at the following results : 



I. That every nerve, of whatever kind it may be, originates 

 from a nerve-cell in the central organs of the nervous system, 

 and terminates at the periphery or in the interior of an 

 organ — 



a. Either in a nerve-cell, and, in the case of the nerves of 

 sense, in the nucleus itself; 



b. Or in the body of a cell, in the interior of the organs, 

 in the case of the ganglionic nerves ; or, lastly, 



c. In the formation of a capillary nervous plexus, in which 

 the anatomical differences disappear, the axial cylinders 

 mutually running into each other and becoming confounded 

 together. 



II. That the nervous system — both central and peripheral 

 — constitutes a whole, Avhich, like the circulating system, 

 pervades every part of the organism, forming a web as it 

 Avere among the different parts, and thus reaching the ulti- 

 mate elements of the tissues, Avithout, at the same time, 

 becoming lost in a vague and confused manner. 



III. That the nervous elements — the cells as Avell as the 

 axial cylinders — arc ahvays in a course of development both 

 in the central organs and at the periphery, 



IV. That the office of the nerve-cells, at the periphery or 

 in the interior of the organs A'aries : they either preside over 

 special functions, as those belonging to all the organs of 



