50 DUBLIN 



7. These divide, appear as rods in the anaphase, and in the 

 telophase give rise to both egg and sperm to eleven or the re- 

 duced number of larger Vs. This is the synapsis stage. 



8. In the youngest oocytes and spermatocytes, the chromo- 

 somes are localized at one pole, having retained both form and 

 place in which they appeared in the preceding oogonial and 

 spermatogonial telophase. 



9. The loop-shaped chromosomes grow very rapidly and soon 

 extend throughout the cells. 



10. The arms of the loops become granular and are longi- 

 tudinally split. 



11. The split bivalents increase the angle between the arms 

 to 180° and then appear as elongated parallel threads of the 

 Cope pod type. 



12. There is no continuous spireme. 



13. The parallel bivalent threads may unite at both pairs of 

 ends to form elongated rings, twine around each other to form 

 8-shaped figures, or come into more intimate relations along the 

 whole length, thus forming extended longitudinally split bars. 



14. These concentrate into the rings and double bars of the 

 first maturation division. 



I 5. At the metaphase almost all the chromosomes are of the 

 elongated longitudinally split rod type, the longitudinal split 

 lying in the long axis of the spindle. 



16. The first maturation division passes through the points of 

 synapsis, and is the reducing division. 



1 7. The longitudinal split does not generally appear in the 

 early dyads, but again makes its appearance in the prophases of 

 the second division as a new construction in the middle. 



18. The second division is a longitudinal one. 



19. The eggs are fertilized internally, pass through the ovi- 

 duct into the atrial brood pouch where they develop. 



20. The pronuclei do not unite intimately. The chromo- 

 somes are very early reformed and give rise to twenty-two V's 

 of the first somatic mitosis. 



21. They split longitudinally and preserve this form through- 

 out all the later divisions up to the last spermatogonial, and very 



