my my 
4 
Later Spermatogonial of Fasciola hepatica. 
_ Fig. 9. Group of four cells. Telophase of penultimate spermatogonial division. (Bouin. ) 
, 10. Portion of periphery of gonad tube showing group of four cells in late telophase 
and spermatogonial cells going into resting. (Corrosive alcohol.) 
» ll. Spermatogonial nucleus between late telophase and resting. (Gil.-Pet.) 
12. Spermatogonial nucleus between late telophase and resting. (F.) 
13. From a group of four spermatogonial cells, (Corrosive alcohol. ) 
» 14. Telophase of last spermatogonial. (Gil -Pet.) 
» 15. Group of eight cells (telophase of last spermatogonial) lying in one plane. 
(Corrosive sublimate acetic.) 
, 16. Telophase. S. (Corrosive sublimate acetic.) 
» 17. Telophase—twelve paired chromosomes emerging from the telophasic mass. S. 
(Corrosive alcohol.) 
Figs. 18,19. Late telophase—twelve paired chromosomes, appearance of plasmosome. 
(Corrosive alcohol.) 
Fig. 20. Very late telophase—gradual disappearance of the chromosomes, S. (Zenker.) 
21. Resting nucleus of spermatocyte I. (F.) 
, 22. Group of spermatocyte I. resting nuclei. (Gil.-Pet.) 
» 23. Leptotene zygotene stage. (F.) 
Figs. 24,25. Pachytene stage. (F.) 
» 26,27. Early strepsitene stage. (F.) 
Fig. 28. Synizetic nucleus. (F.) 
Figs, 29, 30. Early prophase—Fig. 29, from a group of eight cells in one of which there 
is a spindle, 
» ol, 32. Prophase showing twelve bivalent chromosomes, (F.) 
Fig. 33. Chromosomes in nucleus represented in Fig, 32. 
34, Equatorial plate of first meiotic division, (F.) 
» 30. Spindle, chromosomes in metaphase, (Gil.-Pet.) 
S. 
” 
Somatic NUCLEI. 
Fig. 36. Prophase. (F.) 
37. Metaphase. (F). 
38. Late telophase—finger-like protrusions coming out of the telophasic mass. 
(Gil.-Pet.) Only one cell shown fully. 
LITERATURE CITED. 
1. Diveter, M., 1910. Uber die Spermatogenese des Dicrocoeliwm lanceatum, 
Stil. et Hass., Arch. f. Zellforsch., Bd. iv. 
Dustin, L. I., 1905. The history of the Germ Cells in Pedicellina Americana 
(Leidy), Annals N.Y. Acad. Sct., vol. xvi. 
3. Montcomery, T. H., 1900. The Spermatogenesis of Peripatus balfourt up to 
the formation of the Spermatid, Zool. Jahrb. Anat., Bd. xii. 
4. SCHELLENBERG, ADOLF, 1911. Ovogenese, Eireifung und Befruchtung von 
Fasciola hepatica. L., Arch. f. Zellforsch., Bd. vi. 
5. Scuusmann, W., 1905. Uber die Eibildung und Embryonalentwicklung von 
Fasciola hepatica, L., Zool. Jahrb. Anat., Bd. xxi. 
bo 
(Issued separately, 6th December 1916.) 
VOL. XX. G 
