CHROMOSOMES IN THE SPERMATOGENESIS OF THE HEMIPTERA HETEROPTERA. 115 



posed of .") hivalent autosomes and tlie univalent monosome {Mo, Fig. 117) ; the latter 

 can be recognized on pole view by its lesser depth, and on lateral view (Fig. 118) by 

 its quadratic form. The constrictions of the autosomes seen on pole view mark their 

 longitudinal splits, as is very clearly proven by the earlier history of these chromo- 

 somes. The bivalent diplosome and autosomes divide reductionally, the monosome 

 equationally. Fig. Hi) rejjroduces a daughter plate of chromosomes from the early 

 anaphase ; the monosome (Mu) can be recognized as being the only element that shows 

 no longitudinal split. 



Second Matitrafion Division. — Here again there are always 7 elements (Plate XI, 

 Figs. 120, 121), the smallest being a diplosome (Di), and the one that is rounded with- 

 out having any constriction the monosome (J/o). The diplosome and the 5 autosomes 

 always divide, but the monosome passes wholly over into one of the spermatids ; this 

 is shown clearly by the anaphase shown in Fig. 122, where at one spindle pole are 7 

 elements and at the other only 6. 



Literafare. — My preceding description (1901(/) was incorrect in giving 14 as the 

 normal number of chromosomes ; this was because I had counted into the chromosomal 

 plate elements of an adjacent cell. Further, I had entirely overlooked the presence 

 of a monosome, and had not described the second maturation mitosis. 



1 6. CoRizus LATERALIS Say. 



No spermatogonic divisions were found. 



Growth Period. — My preparations had faded considerably so that I could not 

 make out the diplosomes with any certaint}'. But the largest allosome present is the 

 monosome and it becomes longitudinally split. 



First Maturation Division. — There are 7 elements (Plate X[, Fig. 123): 5 biva- 

 lent autosomes and 1 l)ivalent diplosome {Di, di), with components of dissimilar vol- 

 ume) that divide reductionally ; and 1 roundish element, the monosome {Mo), that 

 also divides but equationally. 



Second Maturation Division. — Again 7 elements : 5 autosomes and 1 diplosome 

 {di) that divide again, and a rounded monosome {Mo) that passes into one spermatid 

 without division, as shown in all lateral views of the anaphase (Fig. 125). 



The whole spermatogenesis seems very similar to that of the preceding species, 

 and we may conclude with consideraljle certainty that there will be found in the 

 spermatogonia : 10 autosomes, 2 diplosomes and 1 monosome. 



Literatiire. — My earlier account (19016) was in the main correct, and though I 

 did not decide for the presence of a monosome I noted that one of the chromosomes 

 of the first maturation mitosis differed in form from the others, " for it is not more 



