252 
C. F. U. MEEK. 
with a weak solution of the iron-alum. When a plasma 
stain was used in conjunction with the iron hmmatoxylin, the 
slides were first stained for ten minutes in eosin^ care being 
taken that tlie colour was not destroyed by the strong 
solutions of alcohol in which they were later placed. 
The preparations were studied by means of a Zeiss apochro- 
matic oil-immersion objective of 2 mm. focus and N. A. T30, 
in conjunction with compensating oculars, Nos. 6, 12 and 18. 
When necessary, resolution was facilitated by interposing 
a Gilford screen. The source of illumination was an inverted 
incandescent gas-lamp, used in combination with the holo- 
scopic oil-immersion substage condenser made by Messrs. 
Watson & Sons, of London. All drawings were made with 
a large Abbe camera lucida, and the magnification was esti- 
mated by means of a stage micrometer, graduated to read one 
hundi'edth of a millimetre. Whenever drawings were about to 
be made, both microscope platform and drawing table were 
carefully levelled ; and error due to foi-eshorteuing was 
obviated by making* drawings only of those spindles whose 
major axes lay exactly at right angles to the microscopic line 
of vision, i. e. whose centrosomes could be focussed simul- 
taneously. Moreover, in order to minimise error due to 
draughtsmanship, the centrosomes of each spindle were drawn 
upon several occasions, and at least one hundred times in all. 
The Length of the Mitotic Spindle at the Conclusion 
OF the Secondaey Spermatocyte Metaphase. 
Figs. 1 to 5, PI. 17, are drawings of polar views of the 
secondary spermatocyte metaphase, and all the chromosomes 
are shown. Those chromosomes that are short rods lie on 
the spindle in a manner such that their major axes are at 
right angles to the equatorial plane ; consequently all must 
appear to be spherical in a perfectly polar view. The 
complex is composed of a single ring of ten chromosomes 
with two lying within it, or of a ring of nine chromosomes 
with three within it ; the former ari-angement is seen in. 
