289 



represents the synapsis - point of the original chromosomes — as it 

 probably does judging from similar form and size relations, both the 

 synapsis and the fission being at right angles to the long axis of the 

 elongate chromosomes — this mitosis accomplishes a division of whole 

 chromosomes and is thus a true reducing division. Sometimes the 

 ordinary chromosomes show a precocious longitudinal split at telophase 



Figs. 13, 14, 15 and 16. Postsynapsis ; accessory chromosome in various phases. 



Fig. 17. Early prophase of first maturation mitosis. 



Fig. 18. Later prophase stage ; accessory chromosome bipartite. 



Figs. 19 and 20. Still later prophase; chromosomes pale, mossy and in form of 

 tetrad; accessory U-shaped, compact and chromatic. 



Fig. 21. Final prophase stages. 



Fig. 22. Metaphase groups of four contiguous primary spermatocytes each with 

 18 chromosomes. 



Fig. 23. Primary spermatocyte group of 18 chromosomes with accessory clearly 

 shown to right. 



of the first mitosis, while the accessory invariably does so (Fig. 29). 

 For both types of chromosomes, the second division is equational. The 



Anat. Anz. XXXII. Aufsätze. 



19 



