Davis.— Spermatogenesis. 
PLATE 3. 
Fic. 37. Stage d, primary spermatocyte of Arphia tenebrosa. ‘Two mono- 
somes are present. 
Fras. 38-40. Nuciei of primary spermatocytes of Hippiscus tuberculatus 
showing successive stages in the splitting of the spireme threads. 
Figs. 41-44, Chortophaga viridifasciata. 
Figs. 41, 42.° Stage b, primary spermatocytes. The plane of Fig. 42 is 
perpendicular to that of Fig. 41. 
Fias. 43, 44. Nuclei slightly older than those of Figs 41, 42, showing de- 
velopment of spireme threads from chromatic masses. 
Fic. 45. Stage 6, primary spermatocyte of Melanoplus femoratum. 
Fic. 46. Stage f, primary spermatocyte of Dissosteira carolina. The mono- 
some is seen below at the right. 
Figs. 47-52. Stenobothrus curtipennis. 
Fic. 47. Stage a, primary spermatocyte. The monosome is inclosed in a 
separate vesicle. 
Fic. 48. Stage e, primary spermatocyte. 
Fics. 49-50. Stage e, nuclei of primary spermatocyte. In Figure 49 the 
monosome lies below and at some distance from the distal pole, 
while in Figure 50 it lies close to the pole. 
Fic. 51. Stage e, cross section of polar loops and monosome near the distal 
pole. 
Fig. 52. Stage f, primary spermatocyte. The bipartite structure of the 
monosome is well shown. 
Figs. 53-56. Steiroxys trilineata. 
Fic. 53. Stage a, primary spermatocyte. Owing to imperfect fixation the 
chromatin is shrunken away from the nuclear wall. The mono- 
some lies outside the nucleus. 
Fic. 54. Same stage as Figure 53, but the fixation of the cell is good. 
Fic. 55. Stage c, primary spermatocyte. The monosome has become ap- 
plied to the nuclear membrane. 
Fia. 56. Stage d, primary spermatocyte. The monosome now lies within 
the nucleus. The mitochondrion body is seen in the cytoplasm 
above the nucleus 
