Nov., 1914.] 
Stamens of Smilax herbacea. 
367 
Explanation of Plates XVI and XVII. 
The plates were reduced f in reproduction. All the drawings 
were made with a compensating ocular 12 and a 1-16 oil immersion 
lens. An Abbe camera lucida was used. 
Fig. 1. Microsporocyte before the beginning of the division of the chro¬ 
matin network. 
Fig. 2. Microsporocyte showing the flaky and spongy appearance of the 
chromatin material. 
Fig. 3. Masses of chromatin material which are the protochromosomes. 
Figs 4, 5. Later stages showing the elongation of the protochromosomes 
in their tendency to form a spirem by stretching out along the 
linin thread. 
Fig. 6. Early spirem with irregular flakes along its sides. 
Fig. 7. Early spirem with small granules. 
Fig. 8. Microsporocytes showing the spirem free from the nuclear mem¬ 
brane and collapsing. 
Figs. 9, 10. Sporocytes showing different types of synizesis. 
Fig. 11. Sporocyte in synizesis with the projecting strands showing granules. 
Fig. 12. A synizetic knot with rather heavy projecting loops. 
Fig. 13. Heavy spirem showing granules and beginning of looping. 
Fig. 14. Sporocyte showing the double nature of the spirem and granules. 
Fig. 15. Sporocyte showing the early looping stage and double spirem. 
Fig. 16. Sporocyte showing well formed loops. 
Fig. 17. Chromatin loops completely formed and just breaking apart. 
Figs. 18, 19, 20. Sporocytes showing the prominent chromosomes that 
have not completely separated, but still show some connecting 
threads. 
Figs. 21, 22, 23. Sporocytes showing the twelve mature chromosomes; 
the looped nature of the chromosomes is still evident in most 
cases. 
Fig. 24. Sporocyte showing the delicate connections between the chro¬ 
mosomes and the incipient spindle. 
Fig. 25. Chromosomes in the spindle being drawn into the equatorial 
plane. 
Fig. 26. Early stage of metakinesis showing the chromosomes dividing. 
Fig. 27. Later stage of metakinesis showing most of the chromosomes 
divided. 
Fig. 28. Daughter star of the first division. 
Fig. 29. Daughter cells showing the more or less distinct chromatin masses 
in the nuclei. 
Fig. 30. Mother star of the second division. 
Fig. 31. Daughter star of the second division. 
Fig. 32. Polar view of the twelve chromosomes of a daughter star of the 
second division. 
Fig. 33. Normal tetrad within the old sporocyte wall still showing the 
more or less distinct daughter chromosomes. 
