570 [May 21, 



that every nerve-cell, central or peripheral, has at least two fibres 

 proceeding from it*. In many cases he has demonstrated that these 

 fibres pursue opposite directions, and he considers that such an ar- 

 rangement is general, and therefore necessary. The author considers 

 himself justified in drawing the following conclusions from observa- 

 tions he has made during the last three years. 



1st. That in all cases nerve-fibres are in bodily connexion with the 

 cell or cells which influence them, and this from the earliest period 

 of their formation. 



2nd. That there are no apolar cells, and no unipolar cells, in any 

 part of any nervous system. 



3rd. That every nerve-cell, central or peripheral, has at least two 

 fibres in connexion with it. 



Though the present inquiry is limited to the structure of the par- 

 ticular cells connected with the ganglia in diiferent parts of the frog, 

 the author has studied the arrangement of nerve-cells and nerve- 

 firbes in nervous centres, as well as at their peripheral distribution, in 

 many different animals. 



1. General description of the ganglion-cells connected with the 

 sympathetic and other nerves of the frog. 



The general form of these cells is oval or spherical ; but the most 

 perfectly formed ganglion-cell is more or less pear- or balloon-shaped 

 in its general outline, and by its narrow extremity is continuous 

 with nerve-fibres which may be followed into trunks. 



The figure represents a well-formed ganglion- cell from a ganglion 

 close to one of the large lumbar nerves of the little green tree-frog 

 (Hyla arbor ea). The substance of the cell consists of a more or less 

 granular material, which by the slow action of acetic acid becomes 



* The word " cell" is only used in a general sense, as being shorter and more 

 convenient than " elementary part." It consists merely of, 1st, matter in a living 

 active state (germinal matter}, and 2nd, matter resulting from changes occurring 

 in this (formed material}. In the figure, what is ordinarily termed " nucleus " 

 and " nucleolus " consists of germinal or living matter, while the matter at the 

 lower part of the cell and the nerve-fibres are formed material. A nerve-fibre 

 cannot produce a new nerve-fibre, but the " nucleus " or germinal matter of a 

 nerve-fibre can produce new nerve-fibre. The formed matter never produces 

 matter like itself. Germinal matter can produce matter like itself, and from this 

 formed material may result. 



