594 OHRISTIAN CHAMPY AND H. M. CARLETON 
of their fibres, i.e. ordinary striated and cardiac muscle, the 
influence of cytoplasmic structures on nuclear shape is very 
marked. ‘hus, in striated muscle there is obvious flattening 
of the nuclei against the sarcolemma due to pressure from the 
areas of Cohnheim (i.e. groups of fibrils) of which the fibre is 
composed. 
Often, however, other causes intervene, chief amongst which 
is the influence of the Membrane of Krause (‘Strie Z’ 
of the French and ‘ Zwischenscheibe ’ of the German authors). 
TEXT-FIG. 3. 
A, After Cajal, showing intranuclear rodlet, NR, in pyramidal cell 
from cerebral cortex of rabbit. Technique: Cajal method for 
Golgi apparatus, GA. B, After Retzius, depicting peri-nuclear 
structure (xX) in spermatozoon of the Gasteropod Cypraea. 
This structure is segmentally disposed along the muscle fibril 
and appears in the middle of the dark bands as a clear and 
narrow line. It is best studied in the large fibres of imsects 
(see Text-fig. 10), where it can be seen to constrict the nucleus 
at regular intervals by its projection out of the fibrils into the 
surrounding sarcoplasm. 
A similar appearance of the nuclei can be seen in human 
cardiae and other vertebrate muscle. This is shown in Pl. 23, 
fig. 7. But here we have not been able to follow the membrane 
of Krause as far as the nuclear membrane. Nevertheless, the 
nuclei bear definite constrictions corresponding to the mem- 
branes of Krause of adjacent fibrils, while the curious blunt- 
