BLACKMAN: THE SPERMATOGENESIS OF SCOLOPENDKA. 121 



first spermatocyte consists in the disappearance of the mantle of archo- 

 plasm, which becomes dissolved and in this condition distributed through- 

 out the hyaloplasm of the cell, the presence of archoplasmic suhstance 

 being shown by the darker stain of the inter-reticular areas. 



The centi'osome moves to the nucleus, and divides ; the resulting cen- 

 trosomes separate, migrating along the membrane. During this separa- 

 tion astral rays arise, and by the time the centrosomes are 180° apart 

 have become very numerous and distinct. 



The spindle of the large spermatocytes, when first formed, has its axis 

 perpendicular to the long axis of the cell. During the metaphase it ro- 

 tates, and finally, in the early anaphase, comes to lie with its axis length- 

 wise of the cell. 



During this rotation of the spindle the astral rays increase both in 

 number and length, and the hyaloplasmic areas resume step by step their 

 transparent appearance. The astral rays are believed to be formed by the 

 direct transformation of the latent archojjlasm, as distributed in the hyalo- 

 plasm, into the kinetic fibrillar form. 



In the telophase the persisting spindle remnants are often detached 

 from both cells during the rotation of the cells. The rest of the archo- 

 plasm is again dissolved and distributed through the hyaloplasm. In 

 the following prophase the astral systems again arise by a transformation 

 of this diffused archoplasm. 



During the prophase the centrosomes move apart along the cell mem- 

 brane, and in all subsequent stages of the second spermatocyte division 

 retain this peripheral position. 



Small Spermatocytes. ■ — During the early prophase of the first mitosis 

 the archoplasm collects in a mass upon one side of the nucleus. As the 

 centrosomes diverge and the astral systems appear, this mass of archo- 

 plasm gradually disintegrates. 



When the centrosomes are about 100° apart the nuclear membrane 

 breaks down and an unsymmetrical spindle is formed. This soon elon- 

 gates to form a symmetrical well-developed spindle. 



In the late metaphase the centrosomes leave the p>oles of the spindle and 

 migrate toward the cell wall. The spindle fibres still converge toward the 

 apical points, — the points formerly occupied by the centrosomes, — 

 while tlie astral fibres radiate from the centrosome. The apical point and 

 centrosome remain connected by a few sharply defined fibres. 



Tlie second spermatocyte division is the same in both the large and the 

 small types of cells. 



The phenomena connected with the division of both types of sperma- 



