158 T. H. MONTGOMERY, JR. 



EXPLANATION OF FIGURES. 



FIGS. 1-3. Pole views of spermatogonic monasters of Plethodon ci tier ens. 



FIG. 4. Pole view of a spermatogonic monaster of Diemyctilus virescens. 



FIGS. 5, 6. Pole and lateral views respectively of spermatogonic monasters of 

 Desmognathus fusciis. 



FIG. 7. Oblique pole view of one plate of daughter chromosomes, early sper- 

 matogonic anaphase of Desmognathus fuscus. 



FIG. 8. Lateral view of a late synapsis (postsynapsis) stage of Desmognathus 

 fuscus ; four entire bivalent chromosomes shown, and half of another. Nuclear mem- 

 brane not yet formed. 



FIG. 9. Polar view of a spermatocytic nucleus at a slightly later stage in the same 

 species. 



FIGS. 10-12. Successive prophases of the first maturation mitosis in Desmogna- 

 thus fuscus. 



FIG. 13. Lateral view of a spindle of the first maturation mitosis, showing three 

 bivalent chromosomes in metakinesis ; Plethodon cinereus. 



FIG. 14. A heterotypic chromosome of Plethodon cinereus in its definitive form. 



FIG. 15. Anasa (undetermined species from California), pole view of ovogonic 

 monaster. 



FIG. 1 6. Anasa sp., pole view of spermatogonic monaster. 



FIG. 17. Anasa sp., lateral view of first maturation mitosis, showing six of the 

 eleven bivalent chromosomes. 



FIG. 18. Corpus alternates, pole view of the spermatogonic monaster. 



FIG. 19. Corizus alternatus, lateral view of first maturation mitosis, showing five 

 of the bivalent chromosomes. 



FIG. 20. TricJipepla semivitfata, pole view of spermatogonic monaster. 



FIG. 21. TricJipepla semivittata, lateral view of first maturation mitosis, showing 

 all the bivalent chromosomes. 



FIG. 22. Protenor belfragei, pole view of spermatogonic monaster. 



FIG. 23. Protenor belfragei, late prophase of the first maturation mitosis. 



FIGS. 24, 25. Ascaris megalocephala bivalens, formation of the first polar body 

 (first maturation mitosis), the spindle seen very obliquely in Fig. 25. 



FIG. 26. Idem, formation of second polar body. 



FIG. 27. Si/,.'Hi, lateral view of the first cleavage spindle showing the two groups 

 of chromosomes. 



FIG. 28-30. Idem, pole views of the chromosomes in the first cleavage spindle. 



