Gates. — Somatic Mitoses in Oenothera. 1009 
Stomps, Theo. J. (’10) : Kerndeeling en synapsis bij Spinacia oleracea , L. Dissertation. Amsterdam, 
pp. 162, Pis. 3. 
Strasburger, E. (’05) : Typische und allotypische Iverntheilung. Jahrb. f. wiss. Botanik, xlii, 
i—7 1 ? PI- i- 
Wilson, E. B. (’09) : Studies on Chromosomes. V. The Chromosomes of Metapodius. A Contri- 
bution to the Hypothesis of the Genetic Continuity of Chromosomes. Journ. Exptl. Zool., 
vi, 147-205, Pi. 1, Figs. 13. 
EXPLANATION OF PLATE LXXXVI. 
Illustrating Dr. Gates’s paper on Somatic Mitoses in Oenothera. 
The figures were all drawn with an AbW camera lucida, using a 2 mm. Zeiss apochromat. 
objective, ap. 1*40, and an 18-compensating ocular, and reproduced natural size, giving a magnification 
circ. 3,800 diameters ; except Fig. 15, which is drawn with a low power. The figures were all taken 
from the nucellus of Oenothera lata , except Fig. 38, which represents a megaspore mother-cell. 
Fig. 1. Completely resting nucleus, containing a uniform moniliform reticulum. 
Fig. 2. Cell showing the earliest prophase stage of the nucleus. Certain threads of the reticulum 
are becoming thicker and more markedly moniliform. 
Fig. 3. Slightly later than last figure. The distinction between the thicker and more delicate 
threads is becoming more apparent. 
Fig. 4. Prophase stage, showing the first appearance of definite chromosomes. They are long 
and irregularly coiled. For the sake of clearness only part of them are represented in this figure, 
the fine threads being omitted. 
Figs. 5 and 6. Slightly later stage in which nearly all the chromosomes can be counted. The 
chromosomes are shorter, thicker, and less coiled than in the previous figure, and portions of the fine 
threads of the original reticulum still remain! 
Fig. 7. Later prophase, in which the remnants of the reticulum have disappeared and only the 
chromosomes (fifteen) and the nucleoli are left floating in the cell-sap. 
Figs. 8-1 1 each represent two views of a single uncut nucleus, showing all the chromosomes 
(fifteen) in two planes of focus. 
Figs. Sa, 8 6. A single (uncut) nucleus in two foci, showing all the chromosomes (fifteen). 
The latter are still thin rods, somewhat coiled. 
Figs. 9 a, 9 6. Showing all the chromosomes (fifteen) of another nucleus slightly later than the 
last. The chromosomes are shorter and thicker, one showing a precocious split. Fragments of 
‘ linin ’ remain attached to some of them. 
Figs. 10 a, 10 b. Same stage as last. Chromosomes peripherally arranged, full number (fifteen) 
present, no nucleolus. 
Figs. 11 a, 11 b. Later stage of diakinesis than last, in which the chromosomes all show a clear 
longitudinal split. 
Fig. 12. Last stage of prophase. The longitudinal split in the chromosomes has closed up, 
the nuclear membrane has disappeared and the first indications of the spindle appear as a weft 
of delicate fibrillae surrounding the nucleus. The full number of fifteen chromosomes is present. 
Fig. 13. Slightly before metaphase. The chromosomes are just being drawn into the equatorial 
plate. In this cell the chromosomes are somewhat abnormal in shape. Only twelve are represented 
in the figure. 
Fig. 14. Another abnormal nucleus in metaphase, side view. The chromosomes are arranged 
in two series on the spindle, and are in the shape of dumb-bells. Nine are shown in the figure. 
Fig. 15. An ovule (integuments not shown); a represents the megaspore mother-cell which has 
just undergone the heterotypic division ; b is the cell represented in Fig. 14. 
Fig. 16. Normal metaphase, side view, slightly oblique. The chromosomes have split for the 
anaphase. The spindle is sharp-pointed. 
Fig. 17. Metaphase, polar view. The chromosomes (fifteen) probably all in pairs except a, which 
is unpaired. 
Fig. 18. Same as last. Chromosomes (fifteen) clearly paired, except a , which is the odd 
chromosome. 
