II4 BOTANICAL GAZETTE [FEBRUARY 
Fic. 20. Late prophase, showing nucleolus, two heterochromosomes (rings), 
and seven other chromosomes with indications of pairing; safranin-gentian; 
3.34. XI500. 
Fic. 21. Later prophase showing thirteen chromosomes; the nucleolus and 
one chromosome on adjacent section; no heterochromosomes present; indications 
of pairing of the chromosomes; the cytoplasm is pushing into the nuclear cavity; 
iron-haematoxylin-orange; 7.5. 1500. 
Fic. 22. Nucleolus and ten chromosomes; the stain is withdrawn from the 
shell of the nucleolus, except on one side; iron-haematoxylin-orange; 7.5 #- 
X 1500. 
Fic. 23. Metaphase of heterotypic mitosis, showing twelve chromosomes 
(some paired) and a heterochromosome (h); 5 #. 1500. 
Fic. 24. Same stage as last, showing two heterochromosomes (/) in the cyto- 
plasm, and ten chromosomes on the spindle; 5 #. X 1500. 
Fics. 25-34. O. Lamarckiana (dominant). 
Fic. 25. Section of heterotypic spindle, showing two heterochromosomes (h) 
of equal size on the same end of the spindle; 7.5 #. 1500. 
Fic. 26. Same stage, showing chromosomes closely grouped in the equatorial 
plate; two heterochromosomes (/) of unequal size are present, and a very small 
chromosome (m) out of position on the spindle; iron-haematoxylin-orange; 
7-5¢@. XI1500. 
Fic. 27. Showing chromosomes closely grouped in the equatorial region of the 
spindle, and a small chromosome (m) nearer the pole; iron-haematoxylin-orange; 
7-54. X1500. 
Fic. 28. Showing two smaller paired chromosomes (m) at the side of the 
spindle; 7.54. X1500 
Fic. 29. Polar view of equatorial plate of heterotypic mitosis; one hetero- 
chromosome (h) present; 7.5“. X1500. Fig. 32 is the adjacent section of 
this nucleus. 
Fic. 30. Section of heterotypic spindle, showing a heterochromosome (h), 
an unequal pair of chromosomes, and an equal pair at the periphery of the cell. 
7.5¢@. XI1500. 
Fic. 31. Portion of the spindle, showing two chromosome dyads and a hetero- 
chromosome (h); 7.54. 1500. : 
Fic. 32. Portion of the equatorial plate, showing two very small bodies which 
stain less deeply than the chromosomes and are probably remnants of a hetero- 
omosome; iron-haematoxylin-orange; 7.5 4. 1500 
Fic. 33. Section of equatorial plate of heterotypic mitosis, showing @ number 
of chromosomes, a heterochromosome (i), and a giant chromosome (g), which 1s 
very large and ring-shaped; 7.5 4. 1500. : 
Fic. 34. Equatorial view of heterotypic spindle; the chromosomes at the side 
are displaced in the figure for the sake of clearness; one of them is the giant 
chromosome (g); 7.54. X1500. 
