levine: somatic and reduction divisions in drosera 147 



Later stage, showing fusion of thread-like chromatin bands has begun 



a. Sections of a cell, showing a pachyneme spireme, b. X 2,125. 

 Early stages in the segmentation of the pachyneme spireme, X 2,125. 

 Segmentation of the pachyneme spireme nearly completed, X 2,125. 

 a, b, c. Sections of a cell in diakinesis, X 2,666. 

 Equatorial plate stage, X 2,666. 



Plate 19 



Drosera filiformis 



Fig. 34. Interkinesis, showing the chromosome-like bodies in the cytoplasm and 

 on the spindle fibers, X 2,125. 



Fig. 35. Homoeotypic division in the early telophase, showing faintly stained 

 chromatin-like bodies, X 2,125. 



Fig. 36. Pollen mother-cell divided, showing three cells and their nuclei in one 

 plane. 



Fig. 37. Pollen mother-cell divides, showing all four nuclei. A pair of opposite 

 nuclei lying in a different plane from that of the other. 



Fig. 38. Pollen mother-cell divides, showing four serially arranged pollen cells. 



Fig. 39. Pollen tetrad in process of exine formation. 



Drosera longifolia 

 Fig. 40. a, b. Sections of an embryo sac mother-cell, X 2,700. 

 Fig. 41. Section of pollen grain, X 2,700. 



Fig. 42. Pollen tetrad in which pollen grains are arranged in pairs, a row of germ 

 spores surrounding each pollen grain, X 2,700. 



