KESTETEN ON THE ANATOMY OF THE SPINAL COED. 385 



the cells belonging to the connective tissue, or as sometimes occurs, 

 true nerve cells which have been isolated from the grey substance by 

 the plane of section." 



With reference to the connections of nerve-cells one with the 

 other, the following summary of various opinions may be quoted from 

 Dean. " Schroeder van der Kolk describes and figures, for the most 

 part very truthfully, the communications between cells by means of 

 longer or shorter fibres. He states that two cells are often united 

 by more than one fibre, but so far as my own observations reach, 

 this is exceedingly rare. He seems to infer that cells of the pos- 

 terior cornua are also connected, though he does not mention ever 

 having seen this. Lenliossek speaks of the cells as being multipolar, 

 and connected together in a continuous chain from the apex of the 

 conus medullaris to the brain, and figures the union of several cells 

 from the cervical enlargement of the human cord.* Bidder and 

 Kupffer notice the same fact ; they were also able to make out 

 cell connections in longitudinal sections. Stilling agrees with the 

 authors cited above, considering these cell connections, however, 

 as independent of those he believes established between all the cells 

 of the elementary tuhuli. Both Stilling and Schroeder van der 

 Kolk describe the cell-process as bifurcating, distant cells being 

 connected together by this first divisioji, or by means of still fur- 

 ther ramifications. Stilling carries this division of the cell-process 

 much further than Van der Kolk, making the branches split again 

 and again, till they are reduced to the finest elementary tuhuli. My 

 own observations agree in this respect much more nearly with the 

 figure and description of Clarke ; his statement that the cell-pro- 

 cesses divide and subdivide into smaller branches, so that the space 

 between them appears to be occupied by a minute network of the 

 most delicate fibrils, is entirely correct. I have uniformly seen the 

 cells connected by fibres never smaller than the axis cylinder of the 

 finest nerve fibres of the white substance, being usually (measured 

 at a sufilcieut distance from the cell for the diameter to be uniform), 

 about -0001 -00025" in diameter." 



These connections of the ceU processes, indicated by Lockhart 

 Clarke in 1851, may with care and patience be traced in very thin 

 and transparent longitudinal sections of the horns. As the fibres 

 change their plane, a frequent adjustment of the focus is required 

 under the use of the higher powers of the microscope. The analogy 

 of the relations of the fibres proceeding from unipolar cells in lower 

 classes of animals strengthens the conclusions which have been 

 founded upon the careful examination of the apparently inextricable 

 net-work of cell-processes, nerve-fibres, blood-vessels, and connective 

 tissue. 



The anterior and posterior cornua are divided by an imaginary 

 line drawn across from either side of the central canal outwards to 



This statement must be taken subject to ftiture confirmation. 



