76 bulletin: museum of comparative zoology. 



In the metaphase (Fig. G, p. 74) twenty-three chromosomes can be 

 distinguished in the equatorial plate and, as in all the preceding species, 

 the autosomes can be readily j^aired. 



F. Stenobothrus curtipennis. 



In this species the elements of the testis are smaller than in Dis- 

 sosteira, but larger than in Melanoplus. The apical cell is always 

 present at the distal end of the follicle and is surrounded by a single 

 layer of primary spermatogonia. In the cytoplasm on one side of the 

 nucleus is a mass of material staining deeply with Bordeaux, but it 

 is more homogeneous and less distinctly granular than in Dissosteira. 

 No granules staining with hematoxylin are present. 



The spermatogonia are much as in Dissosteira, but stain more 

 deeply owing to the relatively greater amount of chromatic material. 

 The nucleus is also much more irregular in shape than in Dissos- 

 teira. This is well shown in the prophase (Plate 1, Fig. 17, Plate 2, 

 Fig. 21), where the large vesicular nucleus is more easily distinguisha- 

 ble from the surrounding c}^oplasm. The asters first appear in a 

 deep depression on the distal side of the nucleus. At the center of 

 each aster is a minute centrosome. In the metaphase there are 

 seventeen chromosomes in the equatorial plate, which differ more in 

 size than in the preceding species and thus can be more easily grouped 

 in pairs. In Figures / and J can be seen three pairs of very large auto- 

 somes (1, 2 and 3), which differ not only in size but in shape. The 

 chromosomes of one of the three larger pairs always have the mantle 

 fibers attached to their middle, the two equally long arms projecting 

 away from the spindle in the form of a letter U or letter V. In the 

 case of the other two large pairs, the mantle fibers are attached not 

 at the middle but nearer one end of the chromosome, the projecting 

 arms thus being of unequal length. The next smaller chromosome 

 (4) is the monosome. Between the monosome and the next smaller 

 chromosomes there is a distinct break in the series. The ten smaller 

 autosomes can easily be grouped in five pairs (5, 6, 7, 8, and 9), which 

 constitute a nicely graded series. 



Of all the species studied, Stenobothrus shows most clearly the 

 paired relation of the autosomes. However sceptical one may be 

 about this in the case of the other species described, there can be no 

 doubt that in Stenobothrus there are always, with the exception of the 

 monosome, two chromosomes of each size. 



