136 Allow Burdette Stout 



Summary. 



1. The chromosomes in Carex aquatilis are small spherical bodies 

 which at their maximum development are not more than 0,5 ii in diameter. 



2. These chromosomes are present in all resting nuclei as visible 

 units of definite number. 



3. These individual chromosomes can be traced as such through all 

 stages of both somatic and germ-cell divisions with the exception of the 

 various stages of synapsis. 



4. The spirem of the prophases is discrete: it consists of separate 

 chromosomes whose identity is clearly marked at all stages. 



5. This serial arrangement of the chromosomes is not lost in the 

 division stages. The daughter chromosomes are arranged in a series 

 which remains in evidence during the resting stages. 



6. I am not able to find a longitudinal split through the chromosomes 

 during the prophases. The split first appears as the daughter chromo- 

 somes separate on the equatorial plate. 



7. In the prophases of synapsis the chromosomes spin out at great 

 length into a thin thread, the leptoneme spirem, which is apparently 

 intricately looped and folded on itself. 



8. Synapsis is a well marked stage which can not be regarded as an 

 artefact, and it is followed by a well marked pachyneme spirem which 

 becomes evenly distributed throughout the nucleus. 



9. In diakinesis the bivalent chromosomes form a more or less 

 obvious heterogeneous double spirem. 



10. The heterotypic division is a separation of whole chromosomes 

 which have previously been paired. 



11. In Carex aquatilis, as in Carex acuta (Juel, 1900), but one micro- 

 spore nucleus develops into a pollen grain. 



New York Botanical Garden, N. Y. City, March 1912. 



Literature Cited, 



Allen, C. E. (1903). The early stages of spindle formation in the pollen mother 



cells of Larix. Ann. Bot. Vol. VII. p. 281—311. 

 - (1905). Nuclear division in the pollen mother-cells of Lilium canadense. Ann. 



Bot. Vol. XIX. p. 189—258. 

 Balbiani, E. G. (1881). Sur la structure du noyau des cellules salivaires chez le 



Chironomus. Zool. Anz. Bd. IV. S. 637—641, 662—666. 



