SYMPATHETIC CELLS: ALBINO RAT 293 
are more crowded at certain regions close to the nucleus, forming 
dark masses, but some of them may be loosely scattered toward 
the periphery. It is in this type of cell that difficulties have 
often been encountered in making out the boundary between 
the cell wall and the supporting tissue, because the unstained 
ground-substance is chiefly distributed at the periphery of the 
cell. This type is common after twenty days of age, but is not 
infrequently found after sixty days (fig. 4). 
Type 4. The cells resemble the first type in the arrangement 
of Nissl bodies, but the stainable bodies are much coarser. There 
is a considerable evenness in their distribution, though here and 
there we find a larger dark stainable mass resulting from their 
aggregation. Whether this type is developed from the preceding 
type through modifications in the course of development or 
whether it is directly derived from type 1, without undergoing 
the various changes as in types 2 and 3, is a matter to be settled 
through more detailed investigation (fig. 5). This type is 
characterized by the dense appearance of Nissl bodies throughout 
the entire cell body, not leaving much space for the ground- 
substance, and is common at the age of 124 days and later. 
In interpreting these several types it is to be recalled that 
the cells of this ganglion have severa] different functions and 
there’ always remains the possibility of a correlation between 
function and morphology. 
Besides the four types of cells described above, binuclear cells 
are found at all ages until the rat is very old. In recording 
them, special care needs to be taken. As the cell wall of the 
sympathetic cell is at times difficult to distinguish, two uninuclear 
cells in close contract with each other may frequently resemble 
one cell with two nuclei. In order to avoid error due to such 
misleading appearances, the precaution has been taken to use an 
oil-immersion lens in distinguishing the true binuclear cells 
from those which resemble them. The cells which have their 
cytoplasm discontinuous somewhere between the nuclei or a 
constriction at the middle, either slight or pronounced, as the 
one figured by Apolant (’96, Majer’s ‘cell bridge,’ fig. 8, pl. 
XXIII), were not considered as of the true binuclear type. 
