448 
Chas. W. Metz and Jose F. Nonidez 
9. The spenuatocyte divisioiis are uiiusually clear in A. notatus. 
Tetra ds are not evident and the first division appears to be reductional 
for all of the chromosomes. 
Explanation of plates. 
All of tlie figures were diawn froni material fixed in Flemming’s fluid and staincd 
in iron haematoxylin. Sections in most cases are 5 in thickness. All figures were drawn 
with the aid of the camera lucida, using 1.5 mm Zeiss apochromatic ohjective and 
Ko. 12 ocular, with 160 mm tube length. Drawings were made at table level and are 
reproduced without reduction in size. 
Plate XXI. 
Fig. 2 — 13. Äsilus notatus, spermatogonia. 
Fig. 2 and 3. Metaphases; early spermatogonia, X Y pair in the center. 
Fig. 4. Early resting stage showing the diffuse condition in which the chromatin 
stains very little. Nucleus not entire. 
Fig. 5. Later resting stage, the chromatin collected into seven bivalent aggregates ; 
nucleus entire. 
Fig. 6. Somewhat later resting stage; the aggregates more compact; nucleus entire; 
n — nucleolus. 
Fig. 7. Early prophase ; a bivalent thread arising from each aggregate ; nucleus entire. 
Fig. 8 and 9. Slightly later prophase-stages showing the structure of the threads; 
nuclei not entire. 
Fig. 10. Final spermatogonial metaphase. 
Fig. 11. Final spermatogonial anaphase. 
Fij. 12 and 13. Final spermatogonial telophases. 
Plate XXII. 
Fig. 14 — 25. Äsilus notatus, growth stages of first spermatocyte. 
Fig. 14. Stage a, following the spermatogonial telophase. Only part of the chromatin 
represented. 
Fig. 15. Late stage a, the chromatin staining more deeply, indicating the outhnes 
of the prochromosome-like bivalents; nucleus not entire. 
Figs. 16 — 18. Early, middle and late stage &; seven bivalent cliromosomes, or 
prochromosome-like bodies; nuclei entire. 
Fig. 19. Late stage b, two cells; the bivalent bodies lengthening out into diplotene 
threads; only part of chromatin shown in each nucleus. 
Figs. 20 — 22. Later stages in the transition to stage c; the tlireads are becoming 
longer and less deeply staining; in figs. 20 and 21 the nuclei are entire and all the cluro- 
matin is represented. 
Figs. 23 and 24. Stage c; the threads are intermingled and are polarized with respect 
to the nucleolus ; only those at the upper level are drawn in detail ; nucleus entire in fig, 24. 
Fig. 25. Contraction stage following stage e. 
