A Comparative Stiuly of the Chromosomes etc. 
295 
Fig. 57. Löss of polar arrangement of the loops after the bouquet stage. 
Figs. 58 — 60. Early stages in the formation of the strepsistene threads. The 
37/ pair plainly visible. 
Figs. 61 — 65. The strepsistene stage showing the early Separation of x and ?/. 
The autosomes also separate laterally and twist around each other. 
Fig. 66. Early prophase of first maturation di\nsion. The macrochroinosome 
geniinus (upper part of nucleus) has the form of a ring, x much more Condensed than ij. 
Fig. 67. Later prophase from a smear preparation, showing all ten bivalents. 
Figs. 68 — 69. Two consecutive sections of a single cell in the some stage as 
Figiire 67; all the chromosomes contained in the two sections. 
Fig. 70. Later prophase. xi/ fully Condensed. 
Plate XX. 
Figs. 71 — 102. First spermatocytes of Enchenopa curvata. 
Fig. 71. Netw’ork following last spermatogom'al division. The deeply staining 
nucleolus is probably the a;-chromosome. 
Fig. 72. Beginning of the fonnation of leptotene threads. 
Fig. 73. Leptotene threads fully formed. 
Fig. 7-1. Beginning of zygotene stage. 
Figs. 75 — 76. Two consecutive sections of a single cell, showing both leptotene 
and zygotene threads. 
Figs. 77 — 78. Two sections of a cell showing transition from leptonema to 
zygonema. 
Fig. 79. Early zygotene stage previous to polar arrangement of double threads. 
Fig. 80. Bouquet stage. Lateral ^^ew' showing a;-chromosome at positive (lower) 
pole. 
Fig. 81. Bouquet stage showing ends of the loops viewed from positive pole, 
ar-chromosome indicated by a dotted outline. 
Figs. 82 — 84. Optical sections of late bouquet stage showing all the loops, the 
a;-chromosome, and the chromatic nucleolus. 
Fig. 85. Segmentation of chromatic nucleolus, and loss of polar arrangement of 
the loops. 
Fig. 86. Slightly more advanced than Figure 85. 
Fig. 87. Beginning of strepsistene stage. 
Figs. 88 — 93. Successive stages of the strepsinema, showing the attachment of 
the chromatic nucleoli to the x-chromosome and to autosomes. 
Figs. 94 — 95. Late strepsistene stage, showing the disappearance of the chromatic 
nucleoli. 
Figs. 96—100. The formation of the tetrads from the strepsistene threads. The 
condensation and shortening of the x-chromosome is very noticeable. 
Figs. 101 — 102. Consecutive sections of prophase of first spermatocyte division, 
showing all the chromosomes. 
Figs. 103 — 117. Stages in the formation of the macrochromosome bivalent of 
E. curvata. 
Figs. 118 — 119. Macrochromosome tetrad of E. linolala. Figure 118 from deep 
part of tubule, Figure 119 from edge of section. Material fixed in Hermann’s fluid and 
then stained in crystal violet and alizarin. 
