The spermatogenesis of Peripatus (Peripatupsis) balfouri. 333 



the two centrosomes of a pair no longer makes an angle with the 

 axis of the spindle but is usually perpendicular to it. 



After the metakinesis the daughter chromosomes are pulled apart 

 to opposite poles of the spindle (Figs. 193 — 198); this process must 

 be a rapid one judging from the scarcity of these stages. The move- 

 ment of the chromosomes is in the shortest line to the spindle pole ; 

 accordingly the line of movement of the more peripheral chromosonies 

 forms an angle with the axis of the spindle, so that to secure true 

 lateral views of such daughter chromosomes, they must be seen from 

 a half polar, half lateral position (Fig. 198). The further the chromo- 

 somes become separated from one another, the more clearly can be 

 seen the connective fibres stretched out between corresponding daughter 

 chromosomes ; these fibres are of course morphologically the central 

 linin threads. Each connective fibre is comparatively thick and appears 

 doubly contoured, probably due to its being tubular rather than soHd 

 in structure. 



Later the cell becomes elongated iu the Hue of the spindle 

 (Figs. 198, 200). There is no visible evidence of a central spindle at 

 this stage, so that if it be that the elongation of the cell be due to 

 a central spindle, the latter is invisible. There are movements, prob- 

 ably currents, within the cell body at this time, as is shown by the 

 movement of the yolk globules along the cell membrane to a broad 

 zone in the equatorial plane (Fig. 200), where the cell constriction 

 will be effected. 



The chromosomes finally come to lie at the opposite poles of the 

 spindle; this may, from analogy, be termed the "dyaster" stage 

 (Figs. 200 — 202). They lie often so close together as sometimes to 

 be almost indistinguishable from one another, but they undergo no 

 change in structure and certuinly do not fuse together, as is shown 

 clearly in those cases where they are not closely approximated 

 (Fig. 200). 



It is about the dyaster stage that the division of the cell body 

 occurs. This is effected by a gradually ingrowing annular constriction 

 in the equatorial region (Figs. 200 — 202). There is no formation of 

 either a cell plate or of a spindle plate (Zwischenkörpercheu-plate). 

 The connective fibres are at the equator pushed inwards by the 

 agency of the constriction, and from this point diverge outward to- 

 wards the poles of the spindle. Then they gradually disappear, first 

 those portions of them attached to the chromosomes, then those near 



