SUPRARENAL GLAND—EFFECTS OF INANITION 227 
sum total of the nuclear areas x the thickness of the section. 
The total cell and nuclear volumes for the region would be ob- 
tained by multiplying by the total number of sections. Thus 
it is evident that the ratio of total cell volume to total nuclear 
volume of a region (or of average cell volume to average nuclear 
volume) is the same as the ratio of the total area to the total nu- 
clear area in a typical optical plane. The total area of a section 
is represented by the total paper weight for that section and the 
total nuclear area by the paper weight of the nuclear areas. 
Moreover, the ratio of the average cell diameter to the correspond- 
ing nuclear diameter is the same as the ratio of the cube roots of 
the average cell volume and nuclear volume. Therefore, for a 
given region, assuming that the cells are fairly uniform spheres, 
the average 
*! Total paper weight — 
weight of nuclear areas 
From the cell diameter, the cell volume is readily obtained, and 
the volume of cytoplasm in this average cell will be the difference 
between the cell volume and the nuclear volume. The results 
are given in table 4. Errors in computation! may be checked by 
comparing the ratio of nuclear volume and cell volume with the 
corresponding ratio of the cube of the nuclear diameter and the 
cube of the cell diameter. Crelle’s Rechentafeln were found 
“helpful in the calculations. 
The mitoses were counted in each case in an entire section 
through the middle of the gland. A 2-mm. Zeiss apochromatic 
objective and a mechanical stage were used. ‘The results are 
summarized in table 5. 
Cell diameter = Nuclear diameter x 
1In my previous paper on the hypophysis (Jackson, 717) an unfortunate 
error was made in the calculation of the parenchyma cell diameters listed in the 
last column of table 3, p. 333. Instead of 10.1, 11.9, 13.6, 9.7, 10.2, 10.0, 10.8, 
and 11.0, this column should read: 8.4, 9.3, 10.4, 7.8, 8.0, 8.1, 8.6, and 8.7. A 
corresponding correction is necessary for cell diameters on the lower part of 
page 335, and in the Summary, paragraph 7, page 355, of the same paper. A 
similar correction for the diameter of the parenchyma cells should be made in 
the abstract of that paper, published in the Anatomical Record, vol. 11, p. 370, 
lines 5 to 8. 
