Tlie Idiochiomosomes in Ascaris megalocephala and Ascaris lumbricoides. 429 
Fig. 11. Artificial elongation of protoplasmic process between the halves of the 
idiochromosome. 
Fig. 12. First division telophase. 
Fig. 13. Idiochromosome passing undivided to one secondary spermatocyte 
in worm B. 
Fig. 14. Second division metapliase. 
Figs. 15 — 17. Second division anaphase showing lagging idiochromosome con- 
nected by protoplasmic processes to the dyads other chromosomes. 
Fig. 18. Breaking of the protoplasmic thread from one chromosome-pair, while 
the idiochromosome is drawTi toward the other pair. 
Fig. 19. Second division telophase with the heterotropic idiochromosome in 
one of the spermatids. 
Fig. 20. Artificial elongation of the protoplasmic process from the idiochromo- 
some to the other chromosomes. 
Fig. 21. Separation of the halves of the idiochromosome in worm B occurring 
in the second division. 
Fig. 22. Equatorial plate of the first cleavage division in univalens showing 
the idiochromosome. 
Plate XXII. 
Ascaris lumbricoides. 
Fig. 23. Spermatogonial division showing forty-three chromosomes, the fifteen 
of the lowest focus separated in the figure. 
Fig. 24. First spermatocyte with nmeteen bivalent chromosomes and five uni- 
valent idiochromosomes (i). 
Fig. 25. Equatorial plate of the fhst division. 
Fig. 26. Optical section of the first division metaphase showing the central idio- 
chromosome pentad. 
Fig. 27. First division anaphase with lagging idiochromosome pentad, side view. 
Fig. 28. First division late anaphase: daughter groups of nineteen chromosomes 
arranged in double rings; idiochromosome pentad entering one pole; three quarters 
polar view. 
Fig. 29. Same as fig. 28; a and c, daughter rings of nineteen chromosomes; 
b, idiochromosome pentad; polar view. 
Fig. 30. Idiochromosome pentad showing one larger element with protoplas- 
mic process. 
Fig. 31. Late anaphase, side view. 
Fig. 32. Second division. Equatorial plates of sister ceUs, each with nineteen 
ordinary chromosomes, the upper having in addition the idiochromosome pentad. 
Fig. 33. End of the second division of the secondary spermatocyte with twenty- 
four chromosomes; polar view. 
Fig. 34. End of the second division of the secondary spermatocyte with nine- 
teen chromosomes; polar view. 
Figs. 35 — 36. Spermatids with nineteen ordinary chromosomes fusing together 
and the idiochromosome pentad in the center. 
Figs. 37 — 38. Closing together of the nineteen chromosomes in spermatids 
without the idiochromosome pentad. 
Fig. 39. Equatorial plate of the first maturation division of the egg, showing 
twenty-four chromosomes. 
Archiv f. Zellforschung. T. 
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