514 



Nachdruck verboten. 



Chromatin Reduction in the Hemiptera. 



By F. C. Paulmleb. 

 With 19 Figures. 



The subject of chromatin reduction in the insects is, at the pre- 

 sent time, in considerable confusion, owing to the fact that the four 

 authors who have worked at it, have arrived at quite dissimilar 

 results. 



Henking ^), the first who attempted the study of reduction in 

 insects, did not find any longitudinal splitting and did not observe 

 the genesis of the rings and tetrad-like bodies which he described in 

 Pyrrochoris, but nevertheless came to the conclusion, that the 

 first spermatocyte division was a reducing division; the second, an 

 equation division. Vom Rath-) found in Gryllotalpa a longi- 

 tudinal splitting in the spireme followed by a transverse division of 

 the double spireme into six segments, one half the somatic number. 

 The double segments give rise to rings which then form tetrads by 

 two divisions at right angles to each other, one of them corresponding 

 to the original longitudinal split of the spireme. Without discussing 

 whether both divisions are reducing ones as he maintains, we may 

 simply note the fact that the tetrads are formed by two divisions: 

 one of which is longitudinal, the other transverse. On the other hand, 

 Wilcox^), in Caloptenus, did not find any longitudinal splitting 

 in the spireme, which divides transversely into twelve segments (the 

 somatic number). Each of these segments is composed of two chromo- 

 somes which are formed by another transverse division. These seg- 

 ments join together in pairs to form six tetrad-like groups. Both 

 divisions in this case are reduction divisions. 



The latest contribution to the subject is a paper by Mont- 

 gomery^), on Pentatoma. This author, like Wilcox, finds no trace 



1) Zeitschr. f. wiss. Zool., Bd. 51, 1891. 



2) Arch. f. mikrosk. Anat., Bd. 40, 1892. 



3) Bull. Mus. Comp. Zool., Vol. 27, 1895. 



4) Zool. Anz., Bd. 20, 1897, p. 457. 



