140 CHROMOSOMES IN TIIP: SPERMATOGENESIS OF THE HEMIPTERA HETEROPTERA. 



strated in detail, separate from each other before taking position in the first maturation 

 spindle. Wilson has described these for Lygec.us, Gtenus, Nezara, Euschistus, Brochy- 

 mena, Podisus, Trichopepla ; and they are described in the present paper for Euschistus, 

 Podims, Mormidea, Cosmojwpla, Nezara, Brochyinena, Perilhis, C'cemis, Trichopepla, 

 Eurygaster, Perihalns, Oncopeltus, Zaitha, and Pcecilocapsus. In the last named species 

 and in Tnchopepla much more minute allosomes are found in the growth period, Init 

 cannot be distinguished with certainty during the maturation mitoses. 



A3. Two or more pairs of diplosomes of diverse behavior. In Nahis there are in 

 the spermatocytes two bivalvent diplosomes that remain compact during the growth 

 period, divide reductionally in the first maturation division and equationally in the 

 second, and the components of a pair are equal in size ; and then another pair of 

 diplosomes that are of very unequal size, which are also distinct during the growth 

 period, but which divide separately and equationally in the first maturation mitosis 

 and in the next mitosis (without conjugation in the equatorial plate) divide reduction- 

 ally. In Peliopclta, Ichnodemus and probably Gymus there is a smaller pair, which do 

 not remain compact during the growth period and do not conjugate until late, and 

 these divide reductionally in the first maturation mitosis and equationally in the 

 second ; and besides these there is a larger pair of very unequal components which 

 remain apart from one another during the growth period and then retain their dense 

 structure, which divide separately and equationally in the first maturation mitosis, and 

 in the second spermatocytes conjugate in the equatorial plane and then divide reduc- 

 tionally. Then in Syromasfes Gross has described two pairs of diplosomes : the larger 

 conjugate very early in the growth period, remain dense, divide in the first maturation 

 mitosis reductionally and in the second equationall}'; while the smaller pair, adequal 

 in volume, undergo changes like the autosomes during the growth period, do not con- 

 jugate until after it, and compose a tetrad which divides in the first maturation mitosis 

 but not in the second. Accordingly, this third type of diplosome relations may be said 

 to be a combination of the previous two. 



B. Only Monosomes Present. — This would appear to be the most unusual condi- 

 tion present in the Hemiptera, and is here described for Hygotrechus and Limvofrcchns, 

 while Henking found it for Pyrrhocoris ; in these cases the monosome remains com- 

 pact during the growth period, divides equationally in the first maturation mitosis 

 and does not divide in the second. 



C. Both. Diplosomes and Monosomes Presod, showing the following diversities : 

 CI. One pair of diplosomes of small and adequal volume that usually conjugate 



in the early growth period and during it may either remain comjiact or may undergo 

 changes much like those of the autosomes [Alydus, Metapodms), divide in the first 



