THE EFFECTS OF CENTRIFUGING THE SPERMATO- 

 CYTE CELLS OF NOTONECTA, WITH SPECIAL 

 REFERENCE TO THE MITOCHONDRIA 



ETHEL NICHOLSON BROWNE 



SIX FIGURES 



The spermatocyte cells of Notonecta show a very definite 

 distribution of substances, including the mitochondria, when sub- 

 jected to a centrifugal force. The method of procedure was to 

 dissect out the testes from the insects, put them together with 

 a little Ringer's solution in small glass tubes and centrifuge them 

 for two or three hours with a water centrifuge. The testes were 

 then either teased out on a slide and the cells stained with an 

 intra-vitam stain, Janus green, and examined, or were fixed in 

 Flemming's fluid, sectioned and stained with iron hemotoxylin. 



The nonnal resting spermatocyte cells of Notonecta have been 

 described in a former paper (Browne '13), The cytoplasm con- 

 tains scattered mitochondria of two sorts, fibers and spheres, 

 and the nucleus contains a deeply staining karyosphere in which 

 the chromatin material is collected (fig. 1). When a cell of this 

 sort is centrifuged, the mitochondria are driven to the distal^ 

 pole, where they appear as a deeply staining mass in which 

 individual bodies cannot be distinguished except along the edge 

 (fig. 2). The mitochondria are therefore the heaviest material 

 in the cell. The rest of the cell is filled with clear cytoplasm. 

 The nucleus goes to the centripetal pole, showing that it is of 

 less specific gravity than the cytoplasm. The karyosphere is 

 always driven to the distal end of the nucleus, and in some cases 

 in fact, is driven through the nuclear membrane. 



1 The term 'distal' is used in this paper to denote the pole away from the axis 

 of the centrifuge, the term 'centripetal' to denote the pole nearest the axis of 

 the centrifuge. 



337 



