THE LUMBAR ENLARGEMENT OF THE SPINAL CORD. 331. 
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 exceed- 
ingly rare. He seems to infer that cells of the posterior cornua are also connected, 
though he does not mention ever having seen this. Lenhossék* speaks of the cells as 
being multipolar, and connected together in a continuous chain “from the apex of the 
conus medullaris to the inmost structure of the brain”; he figures the union of several 
cells from the cervical enlargement of the human cord. Bidder and Kupffert 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, how- 
ever, as independent of those which he believes established between all the cells by the 
elementary tubuli. Both Stilling and Schróder van der Kolk describe the cell-process 
as bifurcating, distant cells being connected together by this first division, or by means 
of still further ramification. Stilling carries this division of the cell-process much fur- 
ther than Van der Kolk, making the branches split again and again, till they are 
reduced to the finest elementary tubuli. My own observations agree in this respect 
much more nearly with the figure and description of Clarke;$ his statement that the 
cell-processes *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, if we take for granted that Clarke would not carry the splitting so far 
as to reduce the cell-process to elementary tubuli, which appears to be a just infer- 
ence from his criticisms on Stilling’s views.|| I have uniformly seen the cells con- 
nected by fibres never smaller than the axis cylinder of the finest nerve-fibres of the 
white substance, being usually (measured at a sufficient distance from the cell for the 
diameter to be uniform) about .0001 — .00025" in diameter. 
That some cells are connected together by their processes, as described by the authors 
cited above, admits of no doubt; the results of my own observations, made on the 
cords of the rabbit, calf, sheep, cat, and ox, admitting of the comparison of many 
hundred sections, have been very uniform, establishing beyond any doubt connections 
between some cells in every section of average clearness. "These connections are by no 
means so easy to be made out that careful study is not needed to satisfy the observer ; 
a cell-process rarely runs its course on the same plane, so that constant change of focal 
adjustment is necessary, and the fibres interlace and cross in such confusion, that much 
* Neue Untersuch. iib. d. Feineren Bau d. Centralen Nervensystems, (Wien, 1858,) p. 7. 
t Op. cit., p. 63. t Neue Untersuch., p. 928. 
$ Philos. Trans., 1851, Pl. XXV. Fig. 15. | Quart. Jour. of Microscopical Science, 1860. 
