Reed . — The Nature of the Double Spireme in Allium Cepa . 279 
the anaphase the fission which will effect the separation of the daughter 
chromosomes at the subsequent division is marked out. During the stages 
‘ hooked chromosomes ’ may be seen. 
3. In the telophases lateral fusions take place between the chromo- 
somes, and this has the effect of making the fission more evident. 
4. A chromatin knot is formed by the fusion of parts of chromosomes 
and gives rise to the nucleolus. During the prophase the reverse series 
of changes take place ; the nucleolus gives up its chromatin to the develop- 
ing spireme. 
5. In the ‘ resting ’ stages the nucleus consists of a faintly staining 
reticulum. The chromatin is stored in the nucleoli, and these are joined to 
the reticulum by the fine fibrillar connexions. 
6. The spireme, which is longitudinally split, appears to be continuous 
at first, but later segments into eight subdivisions, and finally these segment 
and give rise to sixteen chromosomes. 
7. No evidence is found in favour of the theory that the sudden 
collapse of the nuclear vacuole is responsible for the appearance of the 
achromatic spindle. 
8. It was not found possible to demonstrate the presence of a distinct 
nuclear membrane. 
9. The gametophytic nuclei, like the somatic, show the double type 
of spireme. 
My heartiest thanks are tendered to Dr. H. C. I. Gwynne-Vaughan 
(Fraser) for providing facilities for the undertaking of this work in the 
laboratory of Birkbeck College and for valuable criticism during its 
progress. 
Bibliography. 
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Phyt., vol. xi, p. 139. 
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type Chromosomes of Tradescantia virginica. Quart. Journ. Mic. Sc., vol. xlviii, p. 559. 
4. Farmer, J. B., and Digby, L. : Somatic and Heterotype Mitoses in Galtonia candicans , 
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6. Gates, R. R. : Somatic Mitoses in Oenothera. Ann. Bot., vol. xxvi, p. 993. 
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