46 MR. C. F. U. MEEK ON 
families, I have included in PJ. J. photo-micrographs of 
spermatocyte cells of two species of Stenobothrus, of which the 
family is sister to that of Forficula. We know that the length 
of the spindle in spermatocyte metaphases cannot be correlated 
with the degree of somatic complexity of the organism; and, 
from the investigations now to be carried out, we shall know if 
the volumes of these cells cannot be so correlated. Moreover, 
the photo-micrographs of cells in Yorficula auricularia and Helix 
pomatia will afford opportunity of verifying my original mea- 
surements of spindle-lengths at the conclusion of the metaphase. 
Material and Methods. 
All material was fixed in Flemming’s strong chromo-aceto-osmic 
acid fluid, in which it remained for twelve hours. It was then 
washed for twenty-four hours in running water; and, after being 
passed through successive strengths of alcohol, was embedded in 
parafiin. Sections were cut 8 or 10 » thick with a Cambridge 
rocking microtome. 
The slides were stained for either twelve hours in Heidenhain’s 
iron hematoxylin, or fifteen hours in iron brazilin. In the 
former’case the mordant was an aqueous solution of ferric 
alum, and the slides remained in it for four hours; in the latter 
case they were put for two hours into a solution of ferric alum in 
70 per cent. alcohol. The iron brazilin enables spindle fibres to 
be seen distinctly, and is a useful stain when camera-lucida 
drawings or photo-micrographs are required. 
The preparations were studied with a Zeiss apochromatic oil- 
immersion objective of 3 mm. focus and N.A. 1:40, and the 
various compensating oculars. The light was obtained from 
a Graetzin lamp, and was passed through the holoscopic oil- 
immersion substage condenser made by Messrs. Watson & Sons ° 
of London. With one exception, all photo-micrographs shown 
were made at the same magnification with a Zeiss camera, the 
apochromatic objective mentioned above, and compensating 
ocular No. 4. The camera extension was 90cm. The magnifi- 
cation was estimated with a stage micrometer graduated to 
read one hundredth part of a millimetre, and a photo-micrograph 
of this scale is included in Pl. II. The negatives and prints 
have not been retouched. 
A Comparison of the Volumes of Spermatocyte Cells in 
different organisms. 
Figs. 1-24 of the Plates are polar and lateral views of cells in 
the metaphase or earliest anaphase. 
Figs. 1-8 inclusive represent spermatocyte cells in 7Z'riton 
cristatus. Fig. 9 represents a primary spermatocyte cell in 
Stenobothrus viridulus, and cells of this generation in S. curti- 
pennis ave shown in figs. 10, 11, & 12; in fig. 12, which is a 
lateral view, the odd or heterotropic chromosome is seen passing 
