EXPLANATION OF PLATES 



Figures are drawn with a camera lucida at an original magnification of 2860 

 diameters, which, in reproduction, is reduced to 1800. The photomicrographs 

 were made with a Zeiss apochromatic 2 mm. N. A. 1.40, projection ocular 4 and 

 Watson 'Parachromatic' oil immersion condenser. The original magnifications 

 were 600 and 1000 diameters which are here reduced to 525 and 875 respectively 



PLATE 1 



EXPLANATION OF FIGURES 



1 to 19 Spermatocyte chromosome complexes from Hippiscus. 



1 to 4 Polar views of first spermatocyte metaphase, with varying number of 

 rings. The accessory chromosome, marked X, appears within the outer circle 

 of chromosomes and is rough in outline. 



5 and 6 Daughter groups in first spermatocyte anaphase. Former associated 

 members of tetrads are seen in the same relative positions in the two groups. In 

 figure 6 the accessory chromosome, A', appears, for which there is no mate in the 

 opposite group. 



7 Lateral view of an early first spermatocj'te anaphase. In figures 5, 6 and 7 

 the dyad character of the anaphase chromosome appears clearly. 



8 to 10 Lateral views of the first spermatocyte metaphase complexes, in 

 which the members have been extended in rows with homologous elements in the 

 same vertical column and with the smaller chromosomes at the left and the larger 

 of the series at the right. The variable shape of the same element at different 

 stages of division is shown. 



12, 13, 16 to 19 Polar views of second spermatocyte metaphase chromosome 

 complexes. The accessory chromosome, X, is present in figures 12, 16, 17 and 19. 

 In figure 17 it is shown surrounded by a vesicle. 



14 and 15 Somewhat oblique lateral views of first spermatocyte metaphase. 



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