CHROMOSOME STUDIES 201 



Another difference shown by obscurus is that both soma and 

 germ cells are smaller than in any other species studied ; possibly 

 a specific difference. 



Obscurus shows conditions of chromosome size sufficient to 

 place it in the genus Acridium; it differs from granulatus and 

 incurvatus in having a greater difference of length between the 

 5's and 6's, a slightly wider gap between the 2's and 3's, a slightly 

 smaller sex chromosome, and smaller cells. 



In the spermatogonia of obscurus both resting and dividing 

 nuclei (figs. 67, 68, c) frequently contain a spherical body (some- 

 times two) which stains like chromatin. At mitosis it passes un- 

 divided to but one of the daughter cells. Its presence in so many 

 spermatogonia indicates that it may divide at some of the divis- 

 ions or at intervening stages. However, when two are present, 

 they are unequal in size. This suggests only transitory bodies. 

 In both the prophase and metaphase of the first spermatocyte, 

 from one to three unpaired bodies occur which may represent 

 one or both spermatogonial bodies (figs. 69-74). One, of course, 

 is the sex chromosome (fig. 69). Of the other two, one (con.) 

 is small and loose; its staining capacity varies, though it never 

 stains deeply, and frequently is almost indistinguishable. It 

 is cone-shaped (figs. 69-74, con.), but sometimes appears partly 

 divided (figs. 72, 73). A third one (c) of the unpaired bodies 

 may be present in either nucleus or cytoplasm. It appears like 

 a chromatoid nucleolus, and may be the sort of structure encoun- 

 tered in the spermatogonia. It is always spherical (figs. 73, 74) 

 and passes undivided to one pole in the first maturation division. 

 These structures behave somewhat like chromosomes in staining 

 and in sometimes being drawn into the equatorial plate (figs. 

 72, 74) at division. It seems possible that the cone-like body 

 (figs. 69-74, con.) may be a chromosome fragment, the result 

 of an unequal division at some previous time. 



5. Paratettix cucculatus Morse. In Paratettix cucculatus (figs. 

 78-84) the cells are decidedly smaller than in Acridium, and the 

 histological appearance is different. In external characters 

 the genus is nearer to Acridium than to Tettigidea, which will 

 be taken up after Parat.ettix. Systematists recognize this fact by 



