The nuclear components of the sex cells of four species of cockroaches. 519 
Fig. 26. Ckromosoraes preparatory to euteriag the metaphase plate. 
Fig. 27. Metaphase of primary spermatocyte. The ocld chromosome lies 
to the left are the pear shaped body. One ordinary chromosome has begun to 
divide. 
Fig. 28. The odd chromosome is passing nndivided to the lower pole. 
The ordinary chromosomes are dividing. 
Plate XXVII. 
Fig. 29. Metaphase showing the longitudinal division of one chromosome 
Fig. 30. Chromosomes with median and sub-terminal attachments. The 
odd chromosome lies to the left. 
Fig. 31. Anaphase, showing the closing of the rings and the migration 
of the odd chromosome towards the lower pole. 
Fig. 32. Late anaphase, wkere the rings have been reduced to compact, 
dumb-bell shaped bodies. 
Fig. 33. Optical section of stage shown in Fig. 32. 
Fig. 34. Telophase. The plasmosome has fragmented, one part being 
seen in one cell, the remainder in the other. The odd chromosome probably 
lies in the upper cell. 
Fig. 35. Early prophase of secondary spermatocyte, showing the odd 
chromosome lying in the lower cell. 
Fig. 36. Stage following 35 where the ordinary chromosomes are very 
attenuated. The odd chromosome is split longitudinally. 
Fig. 37. Formation of chromosomes. 
Fig. 38. Chromosomes contracting down to form the dumb-bells of later 
stages. 
Fig. 39. Late prophase. 
Fig. 40. Later stage of the prophase. 
Fig. 41. Metaphase, showing the metamorphosis of the dumb-bells. 
Fig. 42. Polar views of two metaphase plates, one (left) containing 17 chro- 
mosomes, the other (right) 16. 
Fig. 43. Chromosomes arranged in metaphase plate, preparatory to division. 
Fig. 44. Anaphase, secondary spermatocyte. 
Fig. 45. Telophase of a cell containing no odd chromosome. Plasmosome 
showing in upper cell. 
Fig. 46. Telophase of cell with odd chromosome. The odd chromosome 
is to be seen in each daughter nucleus. The plasmosome lies in the cytoplasm 
of the lower cel|. 
Fig. 47. Early spermatid, showing the odd chromosome in the nucleus 
and the plasmosome in the cytoplasm. 
Fig. 48. Spermatid with no odd chromosome. 
Fig. 55. Spermatogonial metaphase of Leucophaea maderiae, with 23 chro- 
mosomes. 
Fig. 56. Ovarian follicle cell metaphase with 24 chromosomes. 
Fig. 57. Early growth stage, showing odd chromosome (a binary body) 
and the plasmosome. 
Fig. 58. Thickening of the chromatin threads. The odd chromosome is 
dumb-bell in shape. 
Fig. 59. Completion of thickening of the chromatin threads. 
