600 CHRISTIAN CHAMPY AND H. M. CARLETON 
7. Fotps anp INcIsIons IN THE NucLEAR MEMBRANE. 
Such modifications of the nucleus are common, though care 
is required in their observation. This is easiest after fixation 
in fluids which do not precipitate the nuclear contents in too 
coarse a manner, TFixatives such as Gatenby’s Flemming 
without acetic (6) and Champy’s carbol-formalin (4) give the 
best results. 
TEXT-FIG. 9. 
Fig. a.—Diagram showing the relation of intranuclear incisions 
to the nuclear membrane and nucleoli. 
Figs. B and c showing that the shape of the nucleus is governed 
rather by its distance from the cell membrane than by any mass 
action of the cytoplasm. Were nuclear shape the product of 
repulsion between the nuclear membrane and the mass of the 
cytoplasm, the shape of the nucleus in an elongated cell would 
be as shown in B. But this is never the case. In nature the 
long axis of the nucleus is always in the long axis of the cell, 
as indicated in c. The explanation of this seems to be that the 
nuclear membrane is repelled by the cell membrane, and that 
the nearer it is to the latter, the greater the degree of repulsion. 
Gastric epithelium of Amphibia, e.g. of Bombinator or 
Alytes, in which the cells are very large, shows clearly the 
folds in the nuclear membrane. In longitudinal sections of the 
nuclei there may be several of these structures, which may or 
may not traverse its entire length. They are illustrated in 
PI. 23, figs. 1, 7a, and 8. That we are dealing with folds and not 
with canaliculi is made clear by transverse sections of such 
nuclei, which are depicted in PI. 23, figs. 7 B and o, and 8. 
