Voi,. 7, 1921 
GENETICS: J. BELLING 
201 
Up 
Down 
Doubtful 
Third pollen-mother-cell 
4 
4 
1 
Second pollen-mother-cell 
4 
3 
2 
First pollen-mother-cell 
2 
4 
3 
Totals 
10 
11 
In several prophases, one chromosome was disconnected from its cor- 
responding dyad (fig. 2, Nos. 1 and 3). If this occurred more frequently 
it would lead to the condition found in the large-flowered Cannas, where 
triads, dyads, and monads are mingled at the metaphase; or to the situation 
of Osawa's mulberry clones, where triads are apparently less common; 
or finally to the triploid Oenothera lamarckiana, which, according to 
Geerts, 3 shows only dyads and monads. In the triploid Canna, one com- 
plete count of both second divisions was made in a pollen-mother-cell. 
On one side of the cell- wall the numbers were 15 + 1 + 12, and on the 
other side, 13 + 13. The single chromosome seemed attached to the cell- 
wall. 
About half of the pollen-grains of this triploid Canna were nearly or 
quite empty; while the others were full or nearly full of cytoplasm, with 
one or more nuclei. 
Summary. — (1) Most of the Cannas examined were diploid, showing 
nine dyads before the first division in the pollen-mother-cells, and these 
in most plants separated into 9 + 9. 
(2) One of the triploid Cannas showed commonly nine triads, each of 
which separated into two and one on the spindle, in a random manner 
with regard to the two poles. (The same arrangement, though less easy 
to demonstrate, was also found in a triploid Datura.) 
1 Belling, J., 1921, "On Counting Chromosomes in Pollen-Mother-Cells," A m. Nat. 
2 Blakeslee, A. F., J. Belling, and M. B. Farnham, 1920, "Chromosomal Duplica- 
tion and Mendelian Phenomena in Datura Mutants," Science, 52, 388-390. 
3 Geerts, J. M., 1911, "Cytologische Untersuchungen einiger Bastarde von Oe- 
nothera gigas," Ber. Deutsch. Bot. Ges., 29, 160-166. 
4 Miiller, C, 1910, "Uber karyokinetische Bilder in den Wurzelspitzen von Yucca," 
Pringsh. Jahrb. wiss. Bot., 47, 99-117. 
6 Osawa, I., 1920, "Cytological and Experimental Studies in Morus, with Special 
Reference to Triploid Mutants," Bui. Imp. Sericult. Exp. Sta. Japan, 1, 317-369. 
6 Rosenberg, O., 1918, "Chromosomenzahlen und Chromosomendimensionen in 
der Gattung Crepis," Arkiv Botanik, 15, No. 11, pp. 1-16. 
7 Tahara,M., 1910, "Uber die Kernteilung bei Morus," Bot. Mag. Tokyo, 24,281-289. 
8 Tischler, G., 1915, "Chromosomenzahl,-Form, und- Individuality im Pflanzen- 
reiche," Prog. Rei. Bot., 5, 164-284. 
9 Wilson, B- B., 1910, "Studies on Chromosomes VI. A New Type of Chromosome 
combination in Metapodius," /. Exp. Zool., 9, 53-78. 
