14 CALIFORNIA ACADEMY OF SCIENCES. 



fourths the diameter of the nucleus. It is nearly always 

 very regular in outline, strictly globular, and in its early 

 stages shows a homogeneous consistency, its plasma stain- 

 ing intensely and evenly with orange G., but not with 

 hcematoxylon nor with methyl green, and only faintly 

 with safranine (figs. i5; ^l^ ,' ^b; ^id, etc.). In the 

 free Spermatobium the nucleolus always contains one 

 or more, up to six, minute round intranucleolar bodies of 

 different sizes and of an intensely light-refracting nature. 



These intranucleolar bodies are often, but not always, 

 surrounded by a transparent sphere, like a vacuole (fig. 

 /\b). In very young Spermatobia they are absent or few 

 in number; in adult specimens again they are more nu- 

 merous, and I have counted six or eight — some larger, 

 some smaller (fig. .^id.) In a young Spermatobium the 

 nucleolus appears homogeneous, but in older specimens, 

 especially those which are in the stage of division by 

 sporulation (fig. T-ob), I have nearly always found the 

 nucleolus to contain a number of round, lighter-appearing 

 globules, which certainly do not appear as if they were 

 vacuoles, but rather as differentiated nucleolar matter. 



I have also but rarely seen a vacuole. At other times 

 again (fig. 23) the nucleolus seemed to be composed of 

 a few nearly round globules with irregular outlines and a 

 darker center. 



BUDDING OF THE NUCLEUS. 



The diffusion of the macronucleus and the formation of 

 micronuclei in different parts of the Spermatobium is the 

 most interesting fact connected with this protozoa. I may 

 state at once that I have in no instance in this stage of the 

 nucleus observed regular caryokinesis. The division ap- 

 pears to take place only by diffusion or budding. The 

 process of division of the macronucleus in Spermatobium 

 is effected by at least five phases: 



