50 



BIOLOGY OF THE PROTOZOA 



vesicular and the massive. Nuclei of the massive type more clearly 

 resemble the nuclei of spermatozoa being filled with small chromatin 

 granules, but they rarely present the homogeneous appearance of 

 a spermatozoon nucleus, the individual granules, although closely 

 packed, being recognizable (Fig. 23). In vesicular nuclei the 

 chromatin granules may be distributed more or less evenly through- 



Fig. 23. — Types of vesicular and massive nuclei. A, vesicular type of Pelomyxa 

 binucleata; B, of Polystomcllina crispa; both with multiple endosomes; C, nucleus of 

 Actinosphacrium eichhornii with granular plastin (p); D, E, F, macro- and micro- 

 nuclei of Paramecium caudatum, the latter in different stages of vegetative mitosis. 

 (A, B, after Doflein; C, after Hertwig; D, E and F, original.) 



out the nucleus, or they may be segregated in "net-knots" or either 

 alone or combined with other nuclear substances may be combined 

 in one large central globular mass to which Minchin gives the name 

 endosome as an equivalent for the term Binnenkdrper , or they may 

 be aggregated in several such globular masses or multiple endo- 

 somes distributed throughout the nucleus or plastered to the 

 nuclear membrane. 



