SHAPE OF THE NUCLEUS 609 
PLATE 23. 
Fig. 1.—Showing nuclear incisions in a connective-tissue cell from the 
Testis of Astacus. 
Fig. 2.—Oocytes of the fish Silurus sp., showing how the nucleus 
becomes polymorphic at a later stage of development. 
Fig. 3.—Spermatogonium of Bombinator igneus, illustrating 
that the relation of nucleoli to nuclear folds is not constant. Here the 
nucleus has many incisions and yet the nucleoli bear but little relation 
to them. 
Fig. 4.—Tubule cell from a nephridium of Aulostomum—a leech. 
Folds in nuclear membrane orientated in relation to flattening out of 
nucleus. 
Fig. 5.—Two leucocytes from the lymphoid layer of the liver of the 
Axolotl. In A the nucleus is oval and its membrane highly pleated. 
B shows a polymorphonuclear white cell derived from a by the partial 
unfolding of the nuclear incisions. Technique: carbol-formalin and 
ferric Brazilin. 
Fig. 6.—Cell from the hepato-pancreas of Oniscus (an Isopod Crusta- 
cean) showing deformation of the nucleus by large lipoidal granules in 
the cytoplasm. Technique: Benda fixation and iron haematoxylin. 
Fig. 7.—Human cardiac muscle cells. A is a longitudinal section 
showing (i) the pleating of the nuclear membrane, each incision correspond- 
ing to a membrane of Krause, and (ii) the square ends of the nucleus. 
B illustrates the arrangement of the nuclear incisions in transverse section 
at a higher magnification. At the blind end of each incision there is usually 
a nucleolus. c is a longitudinal and somewhat oblique section of the 
nucleus, showing the relation of its shape to the fibrils. Technique : 
carbol-formalin and iron haematoxylin. 
Fig. 8.—Cells from gastric epithelium of the Axolotl. The nuclear 
membrane shows deep longitudinal incisions. Z'S.=a transverse section 
of the nucleus, the relation of the nuclear incisions to the nuclear membrane 
being clearly shown. 
Fig. 9.—Nucleus of cardiac muscle of Astacus, showing relation 
between nuclear incisions and nucleoli. 
Fig. 10.—Longitudinal nuclear folds in germinal epithelium cell of 
Axolotl. 
Fig. 11.—Spermatocyte of Lithobius forficatus—a Myriapod. 
An example of a nuclear membrane of regular contour in spite of 
multiple nucleoli, 
PLATE 24, 
Fig. 1.—Spermatid nuclei of Bombinator—a toad. Showing the 
fully formed axial rodlet in a. 8 and c are different stages in its 
