340 THOS. H. MONTGOMERY, 



dividual fibres can be barely distinguished (Figs. 216, 221); in my 

 figures these have been represented much too distinctly. An exceedingly 

 minute centrosome is present at each pole; sometimes (Fig, 221) each 

 centrosome appears to be immediately surrounded by a small attraction 

 sphere (in the sense of Van Beneden, 1883). 



In the monaster stage (Figs. 217 — 220, Pole views) the chromo- 

 somes are arranged so that their long axes are arranged perpendicular 

 to the long axis of the spindle. The spindle appears nearly round in 

 profile, and its length only about a third of the greatest diameter of 

 the cell. (Some of the figures do not show this greatest diameter.) 



In the following metakinesis the chromosomes become longitudinally 

 separated (Figs. 221, 222), in the same manner that has been de- 

 scribed for the metakinesis of the mitoses of the normal spermato- 

 gonia. It is to be noted that while the spindle elongates somewhat 

 in this stage, its poles fall short of reaching to opposite ends of 

 the cell. 



In the anaphase the appearance is much as in the normal sper- 

 matogonia, except that owing to the shorter relative length of the 

 spindle the two chromosome plates do not reach the cell wall 

 (Figs. 223 — 225). The centrosomes and mantle fibres are very indi- 

 stinct. The cell body constricts, in its progress pushing the connective 

 fibres axially; as a thickening of some of these fibres in the equator 

 is formed a Zwischenkörper-plate (Figs. 224—226). When the daughter 

 cells have constricted apart up to the region of this plate, an inter- 

 esting relation of the cell membrane in this region becomes apparent 

 (Fig. 225): a similar relation has been figured by Meves (1896) 

 for Salamandra. In the equator the membranes of the two daughter 

 cells are contiguous, except in the immediate region of the Zwischen- 

 körperchen-plate, where they are separated by a space that surrounds 

 the latter. May this space be a result of an expansion or growth of 

 the Zwischenkörperchen, which connects the two cells? 



The last stage found in the mitosis of these giant spermatogonia 

 was an early anaphase. The nuclear membrane had appealed in each 

 daughter cell, and the outline of the nucleus appears lobular (Fig. 226). 

 The chromosomes are irregular in form, and some of them show signs 

 of a longitudinal split. 



Reference must here be made to two large resting nuclei. The 

 smaller one (Fig. 212, Plate 22) was found in a mass of normal resting 

 spermatogonia: while much larger than the nuclei of the latter, its 

 amount of chromatin appeared very clear with long linin fibres con- 



