No. I.] SPERMATOGENESIS OF BATRACHOSEPS. 95 



chromoplasts. Stain as the chromatin with the iron-haema- 

 toxylin. Their nature is not known. 



Paralinin Granules. — Larger, deeper staining granules of 

 unknown nature mixed in among the linin granules of the linin 

 network. 



P aranucleolar Graiuiles. — Dark-staining granules, forming a 

 shell around the linoplast or true nucleolus. 



Paraplasniic Gramda. — Granules of undetermined quality 

 found in the cytoplasm. They are often difficult to distinguish 

 from the centrosomes. 



Perfect Bo7iqiiet Stage. — The spireme segments are only 

 slightly longer than the diameter of the nucleus. The seg- 

 ments are more parallel (Fig. 14). 



PlasniospJiere. — The outer, generally lighter staining of the 

 two spheres of the cytosome. It surrounds the inner or grano- 

 sphere, but is sometimes scattered. It furnishes material for 

 the mantle fibers and for the nuclear membrane. 



Polar Fibers. — All fibers radiating from the outer margin 

 of the centrosphere, and which extend in a direction opposite 

 to that of the mantle fibers. Of the same general nature as 

 the mantle fibers. 



Polymorphous Spermatogonia. — The largest spermatogonia 

 with polymorphous nuclei during the resting stage, becom- 

 ing less and less polymorphous, as the leaders are being 

 formed. They divide by somatic mitosis, and possess twenty- 

 four chromosomes. There are three or four generations, but 

 only the first one of these contains polymorphous nuclei. 



Prophases. — All mitotic stages between the imperfect rest- 

 ing stage and the perfect metaphase. The phases in which 

 the chromomeres and the chromosomes are being formed, and 

 their structure finished (Figs. 12-44). 



Radiosomic Process. — The evolution of the spheres, spindles, 

 and fibers ; one of the two independent processes by which the 

 mitosis of the cell is accomplished. This process is presided 

 over by the archosomes and the accessory archosomes. 



Retractile Fibers. — A set of fibers radiating from the poles 

 of the central spindle, when the poles have descended through 

 the ring-like nuclei of the daughter-cells. They end on or 



