596 
Proceedings of the Royal Society of Edinburgh. [Sess. 
calls “ scattered cells ” (Zerstreutenzellen) “ form no definite group. They 
are situated — (1) in the anterior horns ; (2) in the neighbourhood of the 
central canal ; (3) in the Rolandic substance of the posterior horns ; (4) in 
the white matter.” 
Those in the anterior horn and in the neighbourhood of the central 
canal 1 have not been able definitely to separate from the middle cells, and 
have included them in my description of that group. But, for clearness, 
the small cells in the anterior horn are sometimes referred to as the 
scattered cells ; those in the neighbourhood of the central canal as the 
para-central cells — using topographically a term introduced by Onuf and 
Collins (3), without meaning to convey that they are the same cells which 
these authors describe (in the cat) as lying “ ventrad of Clarke’s column, 
on each side of the central canal, and showing in longitudinal sections a 
segmented arrangement.” In man, they further state that “ this group 
seems to have lost its individuality and to form part of Clarke’s column, 
except at certain levels (upper dorsal and middle sacral) where a cell group 
is seen which apparently corresponds to the para-central group, although 
situated considerably more laterally than in the cat.” Elsewhere they 
speak of the cells of the intermediate zone (apparently the middle cells) as 
“ for the most part small, approaching in shape and structure to the cells of 
the lateral horn and of the para-central group.” 
Waldeyer classified the small cells of the posterior horn which “ lie 
posterior to the level of the hindmost part of Clarke’s column, but do not 
form any well-marked group, and are not always present, as (1) Basal, 
(2) Central, (3) Marginal. They are seldom or never all present together, 
and are never in large groups, often only single cells, or at most two or 
three cells. The Basal cells lie immediately behind Clarke’s column, middle 
cells, and lateral horn cells ; the Central cells in the posterior horn nucleus ; 
the Marginal cells on the inner and outer borders respectively of the 
posterior horn, the inner being apparently the more abundant.” I have 
been much puzzled over these cells in the foetal cord : sometimes they can 
be distinguished according to Waldeyer ’s subdivisions, but very often it is 
impossible to separate them from the reticular group of the intermedio- 
lateral tract, on the one hand, and from the middle cells, on the other. In 
appearance and size they are all much alike ; and as regards position, the 
outer marginal cells might be simply a continuation backwards of the 
reticular group, while the basal, and sometimes even the more central and 
inner marginal cells, are often directly continuous as a group with the middle 
cells. I have observed at all levels of the cord, but especially in the lumbar 
segments in all of the situations of these posterior horn cells, certain large 
