CHROMOSOMES IN COREIU HEMIPTERA. I I I 



r.iardina 'oi) on Dytiscus marginalis and likewise those of 

 I laisieux '09) on the same species were confined to the growth 

 period <>t" the oocytes. Both authors describe a large chromatic 

 ma in th.- nucleus of the oocyte, distinct from the chromosomes, 

 which appears to be eliminated just before the maturation divi- 



i- Tin- latter are not described. 

 Orlhoplcra. -The observations of Blochmann ('87) and Wheeler 



, on lilatta germanica were not very extensive from our point 

 "1 \ie\v. 'hiT author determined the number of chromosomes 



in tin- maturation spindles. Wheeler, however, gives a good 

 h^tin nt a cleavage spindle showing 10 chromosomes. Guther/ 

 i a brief paper, described a chromosome-nucleolus in the 

 ! Pyrrhocoris but found no such body in the somatic 

 mi ' Gryllus domestic us. He therefore questioned the occur- 



rence ..i "heterochromoeomes," maintaining that there were 

 prob.il.K 20 chromosomes in the somatic cells of the last nanu <! 

 -pecie- and no "heterochromosomes." However in his later papers 

 '08 ami 'o<><2) he abandoned this view, describing typical "hetero- 

 chromosomes" in the spermatogonia and oogonia of Gryllus as 

 in oilier Orthoptera, and stating further, that the somatic cells 

 ha\e the same number of chromosomes as the oogonia and 

 spermatogonia respectively though he gave no observations in 

 Mipport i -I tin's last statement. The observations of von Baehr 

 n the parthenogenetic egg of the phasmid, Bacillus rossii, 

 though dt tailed in some respects, are not quite conclusive in 



.nl in the number of chromosomes. The egg nucleus, just 

 before the lust polar division, contains 18-20 chromosomes many 

 of \\hich are tetrads. In anaphase the double nature of the 

 daughter halves often becomes apparent. Moreover, there is < me 

 lar-e tetrad in the first division which again appears in the second. 

 Tin number of chromosomes in the latter division was not deter- 

 mined. In a recent paper Buchner ('09) has described in Gryllus 

 inif>t-stris an irregular nucleolus-like structure, the "accessory 

 |po.l\ ." \\hich persists through the growth period of the oocytes. 

 It i- ileri\i-i| from a similar body in the oogonia which he ap- 

 parentU considers identical with the "accessory" chromosome 

 ol other torin-. The maturation mitoses were not observed. 

 ( .inher/ '09 working on a nearly related species, Gryllus domes- 



