160 MR A. ANSTRUTHER LAWSON ON 
EXPLANATION OF FIGURES. 
All the figures were drawn with the aid of the camera lucida, with Zeiss compensating oculars and oil 
immersion objective one-twelfth at the magnifications indicated. 
Figures 1 to 13x 1900. 
Figures 14 to 25 x 1400. 
Figures 26 to 53 x 1900. 
; DIsPorum. 
Fig. 1. A section of a microspore mother-cell when the nuclear cavity has reached its maximum size. Five 
bivalent chromosomes are to be seen and a large nucleolus, The cytoplasmic reticulum shows a uniformity 
of structure. 
Fig. 2. The same at a later stage. A considerable diminution in the size of the nuclear cavity is to be 
seen. ‘The cytoplasm in the vicinity of the nuclear membrane has lost its reticulate structure and takes the 
form of a series of delicate threads which appear to radiate from the membrane. 
Fig. 3. The same at a still later stage, with a further diminution in the size of the nuclear cavity. The 
cytoplasmic radiations have become longer and more sharply defined. 
Fig. 4. The same, showing that the nuclear cavity has diminished to less than half the cubical area shown 
in fig. 1. The membrane is still intact, but a great reduction in the amount of karyolymph has taken place. 
The kinoplasmic radiations are more sharply defined, 
Fig. 5. Another cell showing about the same conditions, but with the nucleus more centrally situated. 
Fig. 6. A still later stage of the same, showing the crowding together of the chromosomes as the nuclear 
membrane closes in about them. 
Fig. 7. The amount of karyolymph has been so much reduced that the nuclear membrane is in close touch 
with the chromosomes for the greater part of its surface. 
Fig. 8. The karyolymph can no longer be seen as a clear nuclear sap, and the nuclear membrane has 
enveloped each individual chromosome. 
Fig. 9. As the nuclear membrane has enveloped each bivalent chromosome, each of these bodies becomes 
provided with a sheaf of fibrils which to all intents and purposes are attached. As these sheaves of fibrils 
appear on opposite sides, there is a small spindle for each bivalent chromosome. 
Fig. 10, The metaphase with the daughter chromosomes separating, and have begun their movement to the 
poles of the spindle. 
Fig. 11. The daughter chromosomes at the poles. 
Fig. 12, Showing the vacuolisation of the daughter chromosomes by the accumulation of karyolymph and 
the organisation of a membrane about each daughter nucleus. 
Fig. 13. The daughter nuclei completely organised. 
GLADIOLUS. 
Fig. 14. A section of a microspore mother-cell with the nucleus at its maximum size. 
Fig. 15. A slight diminution in the size of the nuclear cavity is shown, and a narrow weft of kinoplasmice 
threads appears about the nuclear membrane. This weft is not uniform, being much more prominent at 
intervals. 
Fig. 16. A typical multipolar condition of the kinoplasm. 
Fig. 17. The same a little later, showing four cones in the multipolar condition. The nuclear vacuole 
has decreased to less than half its original dimension, 
Fig. 18. The same, showing three cones in the section. 
Fig. 19. Another example of the same stage, showing two cones. 
Fig. 20. A little later stage, showing the nuclear membrane still intact. 
Fig. 21. Another example about the same stage. 
Fig. 22. The nuclear vacuole has so much reduced that the membrane is seen closing in about the 
chromosomes. 
Fig. 23. The nuclear membrane has now enveloped each chromosome. 
Fig. 24. The same a little later. 
Fig. 25, The mature spindle with the chromosomes at the equator. 
