120 CHROMOSOMES IN THE SPERMATOGENESIS OF THE HEMII'TERA HETEROPTERA. 



some that appears to be regulai'l}^ constricted (il/o) ; and 9 pairs of autosomes 

 iA,a-J,i). 



Ovogonic Divisions. — On the only two clear pole views upon my preparations 

 there were exactly 22 elements. A careful comparison shows that the odd one of the 

 spermatogonia, the monosome {Mo, Fig. 164), is represented in the ovogonia (Figs. 

 162, 163) by a pair of elements {Moj^vio) ; each component of this ovogonic pair is of 

 about the same volume as the single monosome of the spermatogonia. In the ovo- 

 gonia there are also a pair of diplosomes of dissimilar volumes. 



Growth Period. — The monosome and the diplosomes show the same behavior as 

 in the preceding species, and the longitudinal spHt of the monosome is very distinct. 



First Maturation Division. — Pole views show 11 elements, in the. center the bi- 

 valent diplosome (/>/, <Ji, Fig. 165) and a bivalent autosome, then a circle of 8 bivalent 

 autosomes, and outside of the latter the monosome {Mo). All of these divide reduc- 

 tionally except the monosome {3Io, Fig. 166) that divides equationally. 



My preparations contained no second maturation mitoses, but proba1)ly the 

 monosome will be found to behave in them as it does in Anasa tristi.'^. 



Literature. — My earlier account (1901/^) was erroneous in stating the sperma- 

 togonic number of chromosomes to be 22 ; because the monosome there is regularly 

 constricted I was misled into counting it as two. And that led to the further mistake 

 of concluding the allosome of the growth period to be the bivalent diphjsome. 



23. Anasa armigera Sa3^ 



Spermatogonic Divisions. — On the only two clear pole views of chromosomal 

 plates 21 elements could be counted (Plate XI, Fig. 167) ; here the monosome is the 

 only one that is somewhat constricted {Mo) and is not the largest ; then there are 2 

 very small diplosomes {Di, di) of nearly equal size, and 9 pairs of autosomes {A, a-I, i). 



Groivth Period. — The staining of my single preparation was not ftworable for 

 determining the behavior of the diplosomes, but the large allosome must be the 

 monosome on account of its similarity to that of the other species of this genus. 



Fint Maturation Division. — There are 11 elements, all shown in Fig. 168. The 

 smallest is the bivalent diplosome {Di, di), while the monosome can be recognized by 

 its unipartite appearance {Mo). I liave seen stages no later than this metaphase, l)ut. 

 it is sufficient to show that the autosomes and the diplosomes divide reductionally. 



Literature. — My previous very brief account (1901/>) made the same mistakes as 

 I had made for the other species of the genus. In the figure then given of the sper- 

 matogonic chromosomes (Fig. 77, 19016) I had counted the constricted one just to the 

 left of the two diplosomes as two whereas it is really but a single monosome : my 

 drawing was more correct than my reasoning. 



