MALE GERM CELLS IN NOTONECTA 81 



volume is nearly twelve times as great. About half of the increase 

 in size takes place before the disappearance of the spireme, the 

 other half after the karyosphere is fully formed (figs. 51, 52, 53). 

 The growth of the spermatocyte in Notonecta is so great as to 

 be comparable with that of an oocyte (as was noted also by Pantel 

 and Sinety), and it must involve a similar metabolic activity. 

 It is well known that in the eggs of many forms, some of the chro- 

 matin is ehminated during the growth or maturation divisions; 

 this is probably correlated with the metabolism of the cell. The 

 diminution of the chromatin by a casting off of the ends of the 

 chromosomes in Ascaris megalocephala and A. lumbricoides is 

 probably of a similar nature. The ring in Dytiscus (Giardina 

 '01) which during four divisions passes to only one of the resulting 

 cells, i.e., the oocyte, has likewise been interpreted by Boveri 

 ('04) and Goldschmidt ('04) as representing chromatin that is 

 concerned in the nutrition of the cell. For a comprehensive 

 account maintaining the existence of two kinds of chromatin, 

 basichromatin and oxychromatin, see Stauffacher ('10). 



2. Description of karyosphere. The appearance of the karyo- 

 sphere varies considerably with the stage of growth, with differ- 

 ent fixing fluids and stains and with the amount of extraction. In 

 many preparations, especially those stained deeply with haema- 

 toxylin, no structure is evident; it is merely a round or approxi- 

 mately round mass of vesicular appearance (fig. 54 A). In other 

 preparations an irregular contour and difference in staining capac- 

 ity in different regioAs gives it a spongy appearance (figs. 54 B, 

 55). In haematoxylin preparations well extracted and in saf- 

 franin preparations the structure is quite definite. The karyo- 

 sphere consists apparently of dense, compact bodies of varying 

 size embedded in a less dense matrix (figs. 53 A, 54 C, D), the for- 

 mer being probably the chromatin proper. When crowded these 

 bodies give somewhat the appearance of a continuous spireme 

 closely convoluted (fig. 53 A). In the younger stages, the karyo- 

 sphere tends to have a vesicular appearance, and later the spongy 

 ' or granular structure is more evident. In the living material, 

 the differentiation of two sorts of material in the karyosphere is 

 perfectly evident, the denser substance taking the form of com- 



THE JOURNAL OP EXPERIMKNTAL ZOOLOGY, VOL. 14, NO. 1 



