324 CHI PING 
and the maximum number of these cells is never above ten. 
There seems to be a tendency for the binuclear cells to increase 
in number during the middle age of the animal. ‘The diameters 
of some of these cells and those of their two nuclei, as well as the 
nucleus-plasma ratios derived from these diameters, are recorded 
in table 7. 
According to table 7, the nucleus-plasma relation is 1:4.6 
in a very young rat and 1:4.1 in an old rat, as indicated by the 
body weight, and throughout the series the values are fairly 
constant, though with a slight tendency to diminish. This 
agrees with what has been found in the Albino and shows that 
TABLE 7 
Diameters of some of the binuclear cells and of the two nuclei in each of them. Data 
arranged according to body weight. The nucleus-plasma ratios are shown in the 
last column. Norway rat 
DIAMETER OF RATIO OF VOLUME OF 
BODY WEIGHT : CYTOPLASM TO VOLUME OF 
Cell Two nuclei ENAGIINITE EIDE 
grams iM M 
13.6 25.0 11.6 + 10.7 1 :4.6 
33.0 29.9 13.4 + 13.4 1 :4.6 
115.0 26.3 13.4+ 8.9 1:4.8 
169.2 28). 1 13.4 + 12.9 12329 
243.2 204 12.0 + 13.4 I 401 
230.2 25-1 13.4 + 13.4 WB ioe 
in the binuclear cells there is an increase in the nuclear mass 
which is not accompanied by the same enlargement of the cyto- 
plasm, as is found in mononuclear cells. In their nucleus-plasma 
relation, therefore, these binuclear cells are like very young cells, 
and in the older animals at least they certainly do not represent 
two normal mononuclear cells pressed together. 
Pigmented cells 
It is somewhat surprising to find that the pigmented cells 
in the superior cervical ganglion of the Norway are not very 
numerous, as table 6:shows. In no case were they found in all 
of the individuals of a group. They do not appear in the young 
