The Spermatogenesis in Pentatoma up to the Formation of the Spermatid. Q\ 



chromosomes, i. e. that one of them may frequently if not usually 

 receive a whole undivided chromosome; either Pyrrhocoris shows a 

 marked peculiarity in this respect, or else Henking had mistaken 

 either a yolk globule or a chromatin nucleolus for an undivided 

 chromosome. It is only by the use of double stains that yolk globules 

 (Yk. Gl Fig. 202), which persist in many cells up to the formation 

 of the spermatid, may be easily distinguished from the chromosomes. 

 Each 2nd spermatocyte appears as a rule, if not always, to receive a 

 half of the original chi-omatin nucleolus {n. 2 Figs. 207 — 212), other 

 fragments of this element persist still in some cells. Fig. 206 presents 

 a case where the division of the chromatin nucleolus lagged behind 

 that of the chromosomes. 



In the completed dyaster of the 1st spermatocytic division occurs 

 the separation of the daughter cells, i. e. the 2nd spermatocytes 

 (Figs. 201, 202, 206). The original mother cell is biscuit-shaped, due 

 to a constriction of the cell body which is equally deep on all portions 

 of the equator of the cell. This constriction cuts as deeply as the 

 bundle of connective fibres {Cyi. F Figs. 201, 202, 206) of the 

 previous metakinesis, but a certain period of time appears to elapse 

 before it cuts through this portion also. At this stage we find the 

 tertiary central spindle {c.sp.3 Figs. 201, 202) at right angles to the 

 original (secondary) central spindle {c.sp.2), and the chromosomes 

 lying in a mass near its equator, connected by mantle fibres with the 

 centrosomes. The pole rays are now feebly developed. The original 

 connective fibres still persist, and connect the chromosomes of the one 

 cell with those of the other. The remnant of the secondary central 

 spindle (c.sp.2 Figs. 201, 202) still connects one centrosome of one 

 cell with one of the other; in certain cells it seemed that this 

 secondary spindle had become divided into two, at the time of 

 separation of the centrosomes (in the metakinesis). The idiozome 

 substance (Id. Z) forms a cylindrical sheath around the connective 

 fibres, the sheath being thickest near the chromosomes. The two 2nd 

 spermatocytes now completely separate, and at the point of separation 

 the connective fibres and secondary central spindle form for a time 

 a bridge between the two cells. Thickenings at the equator of the 

 fibres were found in only a few cases (Fig. 202), though they are 

 regularly present in the 2nd spermatocytic division. 



