On Morpbological Difiference of the Chromosomes of Ascaris megalocepb. 75 
Vejdovsky, F. 1907. Neue Untersucbungen Uber die Reifung und Befrucbtung. 
Prag. 
Wheeler, W. M. 1897. The Maturation, Fecondatiou and Early Cleavage of 
Myzostoma glabruui. Arcb. de Biol. 15. 
WiLSOx, E. B. 1905a. Studies on chromosomes. 1. Journ. Exper. Zool. 2. 
1905b. Studies on Chromosomes. 2. ibid. 
Zacharias, 0. 1887. Reue Untersucbungen über die Kopulation der Geschlechts- 
prodnkte etc. bei Ascaris megalocephala. Arcb. mikr. Anat. 30. 
Explanation of Plates VI and VII. 
All the figures are frora camera lucida drawings, and all those referring to 
Ascaris (1 — 73) are made to the same scale. 
Plate VI. 
Figs. 1 — 35. Pole views of equatorial plates of the first cleavage. 
Figs. 36 — 42. Pole views of equatorial plates of the second cleavage. 
Plate VII. 
Figs. 43—47. Later prophases of the first cleavage. 
Figs. 48—52. Earlier prophases of the first cleavage. 
Fig. 53. Second polar spindle at the surface of the egg and sperm chro- 
mosomes at the centre. 
Figs. 54—65. Oblique lateral views of second polar spindles. 
Fig. 66. Chromosomes of the first polar body. 
Fig. 67. End of the first maturation, showing the two dyads left in the 
egg and the sperm chromosomes at the centre. 
Figs. 68 — 71. Sperm chromosomes, at the stage when the first polar spindle 
is at the surface and the sperm at the centre of the egg. 
Fig. 72. Sperm chromosomes, at the stage of the second polar spindle. 
Fig. 73. Mature sperm before copulation. 
Fig. 74. Pole view of spermatogonial equatorial plate of Harmostes reflexu- 
lus (Hemqiteron). Mo, monosome, Di and di the diplosomes, A, a — E. e the 
nnmodified chromosome pairs. 
Fig. 75. Pole view of spermatogonial equatorial plate of Corizus alternatus 
(llemipteron). Lettering as in Fig. 74. 
