PLATE 10 



EXPLANATION OF FIGURES 



139 Copy of Davis' text figures Oa, Ob, Oc, rope models to explain his con- 

 ception of the structure and method of division of the ring chromosomes. From 

 these it will be observed that the rings lie in the plane of the spindle axis and 

 that the longitudinal cleft is, therefore, not in the equatorial plate. 



140 Photograph of a series of wax models of the chromosome complex of 

 Tropidolophus shown in figures 29 and 110. These were prepared after a careful 

 study of the group and they were arranged in the same relative positions in which 

 they appeared in the cell. The central opening of the rings was purposely made 

 larger in order to exhibit their structure more clearly. Compare these with figure 

 139 in order to see most clearly the difference between the conception of ring 

 formation advocated by de Sinety, Davis and Montgomery and that held by 

 myself and students for the Hippiscus type. 



141 Copy of Granata's text figure 1 illustrating his interpretation of tetrad 

 formation in Pamphagus. His view of the formed tetrad is essentially similar to 

 my own, even to the compound ring. 



142 Copy of Morse's text figure 1, showing various interpretations. The 

 series in the first row are copies of Sutton's figures and represent my own concep- 

 tion. The second row presents Davis' view, the third is Morse's explanation of 

 the chromosome forms in Periplaneta, and the fourth is to illustrate the Schreiner's 

 interpretation of Tomopteris. This series of figures representsclearly the various 

 interpretations which I have discussed elsewhere. 



143 Photograph of the ring- and cross-shaped wax models shown in figure 140. 

 These demonstrate that such forms are indistinguishable from each other when 

 viewed en face, and also that rings constituted as I have described them, when 

 viewed obliquely, appear as loops with crossed ends. 



144 Diagrams by Otte to illustrate his conception of a double cross division, 

 with chromosomes of similar appearance in first spermatocyte (E, F) and second 

 spermatocyte (H, J). Compare these with the figures of these generations of cells 

 in various Orthoptera given in this paper. 



145 Figures 148 and 149 of de Sinety to show the method of division in chromo- 

 somes with terminal (A), subterminal (B), and median (C) fiber attachment. 

 Figures marked A illustrate the conception of ring division first advocated by this 

 author and later supported by Davis (fig. 139) and Brunelli (figs. 146-147). Those 

 marked A' are to explain chromosomes of the first spermatocyte metaphase in lat- 

 eral view with diverging ends where the fibers attach and at the opposite side. 

 These are in reality rings with the contrasynaptic ends extended. 



146 and 147 Copies of Brunelli's figures 11, 12, 14, 15, illustrating his ideas of 

 chromosome division in the first spermatocyte. These are essentially like those 

 of de Sinety. 



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