601 
1907-8.] Middle Cells of Grey Matter of Spinal Cord. 
para-central group is the most common. In other regions only scattered 
cells occur. In size they appear to be of mixed sizes in all areas ; their 
distribution lengthwise is typical of the middle cells — here one section, 
gone the next. 
C 4. — The description given of C 3 applies practically unchanged to 
this segment, although, with the growth of the lateral motor group, the 
middle cells disappear from the outer portion of the base of the anterior 
horn, but they may still be seen between the motor nuclei. On the whole, 
the cells are both rather more numerous and rather larger than in C 3, 
Fig. 3.* 
Cl— 162L(x33 ). 
a. Scattered cells in the base of the anterior horn. 
b. Middle cells scattered over the area of the lateral horn and the 
reticular formation. 
c. Group of middle cells in the posterior part of the central-para- 
central area, including a few of larger size than elsewhere, all 
the others being small. 
particularly the more anterior cells, though here also the difference in size 
between these and the others is not at all marked. 
C 5. — Cells increasing in number, descending the segment, also tending 
to be more grouped. Anterior to the frontal plane of the central canal few 
and scattered, but often of larger size than elsewhere, sometimes not much 
smaller than motor cells. In the reticular formation, scattered at first and 
sometimes outlying in the white matter, oftener small groups in the lower 
part. A central group more often in upper part than in lower. In lower 
part of the segment frequently a well-marked band of cells stretching 
* These figures in the text are traced from photographs, and give exact position of cells and 
approximately their relative sizes and shapes. The numbering is as follows : — C 1—162 L means 
the 162nd serial section from the top of the first cervical segment, the left side. 
