MORPHOLOGY 



43 



while nuclear membrane and achromatic substances remain unat- 

 tacked; and (4) in the fixed condition Feulgen's nucleal reaction 

 (p. 897). Action of methyl green (Pollister and Leuchtenberger, 

 1949). 



There is no sharp demarcation between the vesicular and compact 

 nuclei, since there are numerous nuclei the structures of which are 



Fig. 3. Parts of 



nacronuclei of Nyctotherus ovalis, showing chromatin 

 spherules of different sizes, X650 (Kudo). 



intermediate between the two. Moreover what appears to be a 

 vesicular nucleus in life, may approach a compact nucleus when 

 fixed and stained as in the case of Euglenoidina. Several experimental 

 observations show that the number, size, and structure of the endo- 

 some in the vesicular nucleus, and the amount and arrangement of 

 the chromatin in the compact nucleus, vary according to the physio- 

 logical state of the whole organism. The macronucleus may be 



