287 ■ 



maternal and paternal elenoents, Montgomery, '02) chromosomes to 

 form bivalent post-synaptic chromosomes. 



Frequently a longitudinal split appears transitorily in these threads. 

 During synapsis the accessory chromosome assumes a position to the 

 side of the group of ordinary chromosomes (Fig, 10) but more usually 

 it lies at the base of the group. Just how intimate is its connection 

 with the ordinary chromosomes during synizesis and synapsis could 



(The figures were all drawn with Bausch and Lomb Yi« oil immersion lens, ocular 

 No. I. The drawing surface was at 150 mm below the level of the stage. The figures 

 have been reduced '/^ giving a magnification of 1400.) 



Fig. 1. Primary spermatogonium, resting stage. 

 Fig. 2. Metaphase group of 35 chromosomes. 

 Fig. 3. Secondary spermatogonium, resting stage. 

 Fig. 4. Metapliase group of 35 chromosomes. 

 Fig. 5. Side view of metaphase group of chromosomes. 

 Fig. 6. Metaphase group of follicle cell of ovary with 36 chromosomes. 

 Fig. 7. Late telophase of final secondary spermatogonial mitosis; lower cell 

 howing accessory chromosome. 



Fig. 8. Primary spermatocyte, resting stage. 

 Fig. 9. Presynaptic stages of growth period. 

 Figs. 10, 11 and 12. Synapsis. 



not be definitely determined. Its position indicates a rather close re- 

 lation at this stage with the general activity of the chromatin. It 

 usually also shows a decided longitudinal split. During early post- 



