136 
Arlow Burdette Stout 
Summary. 
1. The chromosomes in Carex aquatilis are small spherical bodies 
which at their maximum development are not more tlian0,5_n in dianieter. 
2. These c-hromosomes are present in all resting nuclei as \isible 
units of definite number. 
3. These individual chromosomes can be traced as such through all 
stages of both somatic and gerni-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 aiTanged in a series 
which remains in eAudence during the resting stages. 
6. I am not able to find a longitudinal spht through the chromosomes 
during the prophases. The split first appears as the daughter cliromo- 
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 foUowed 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 heterotyiHc dhdsiou is a Separation of whole chromosomes 
which have pre^•iously beeil paired. 
11. In Carex aquatilis, as in Carex acuta (Juel, 1900), but one niicro- 
spore nucleus develops into a poUen grain. 
Xew York Botanical Garden, X. 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). Xuclear division in the pollen mother-cells of Lilium canadense. Ann. 
Bot. Vol. XIX. p. 189—258. 
Balbi.lxi. E. G. (1881). Sur la stnicture du noyau des cellules salivaires chez le 
Chironomus. Zool. Anz. Bd. IV. S. 637 — 641, 662 — 666. 
