336 THOS. H. MÜNTGOMEKY, 



position as it occupied in the metakinesis of the former division. In 

 my paper on Penfatoma (1898) I correctly interpreted the 1st ma- 

 turation division as a transverse splitting of the chromosomes, i. e. 

 as a separation of entire univalent chromosomes. But in that paper I 

 interpreted the 2nd maturation division as likewise a transverse division 

 of the chromosomes (reduction division in the sense of Rückert, 1894), 

 for then I had not interpreted the position of the constriction of the 

 chromosomes correctly and consequently assumed that these chromo- 

 somes were turned on their axes through an angle of 90°. This 

 longitudinal split in the chromosomes was quite correctly interpreted 

 by Paulmier in a preliminary note (1898); and in a note of my own 

 (1899) I acknowledged the correctness of Paulmier's conclusion : my 

 error was one of interpretation rather than of observation. Accordingly 

 in the Hemiptera just as in Feripatus^ the 1st maturation division 

 separates entire univalent chromosomes (is a reduction division in the 

 sense of Weismann), the 2nd maturation division is an equation 

 division. Since then, as has been shown in another section of the 

 present paper, the split of the univalent chromosome of the 2nd 

 spermatocyte is a true longitudinal split corresponding perfectly in 

 position with the longitudinal split of the early prophase, it follows 

 that the univalent chromosome does not become turned upon its axis 

 to take its place in the equator of the spindle; and hence in Penta- 

 toma also there can be no such torsion of the chromosomes as had 

 been at first assumed by me for Pentatoma. 



The early reappearance of the longitudinal split in the meta- 

 kinesis of the 1st maturation mitosis cannot be ascribed to any agency 

 of the mantle fibres, but rather to an active movement on the part 

 of the chromatin itself. 



In the metakinesis of the 2nd maturation division each chromo- 

 some becomes halved in the plane of the longitudinal split (Figs. 204 

 — 208), so that each daughter cell (spermatid) receives one half of 

 each of the 14 chromosomes of the mother cell (2nd spermatocyte ; 

 Figs. 209, 210). Dependent upon the form of the chromosome, and 

 upon the position of its longitudinal split, is the position of the plane 

 of division; thus while the plane of division may sometimes be per- 

 pendicular to the long axis of the chromosome, in other cases it may 

 be parallel to it. But a careful study shows that with great prob- 

 ability all the chromosomes of the 2nd maturation division are halved 

 through a plane that coincides with the plane of the longitudinal split. 

 In this way each daughter cell receives a half of each chromosome of 



