606 Wisconsin Academy of Sciences, Arts, and Letters. 
ured lying near one another side by side to form pairs. This 
arrangement in pairs is seen more or less distinctly through the 
anaphases and in early telophases. 
The pairing of chromosomes even in resting nuclei has been 
reported by Overton (74), who has observed prochromosomes 
in the somatic nuclei of Podophyllum and Calycanthus ar¬ 
ranged parallel in pairs and connected by linin intervals. In 
the resting nuclei of the pollen mother cells of these species 
this arrangement in pairs is still seen, as well as in the later 
prophases of the heterotypic division. 
Very recently Strasburger (100) has discussed at greater 
length the subject of pairing of homologous chromosomes. He 
reports that in chloralized root-tips of Pisum sativum, in those 
cases in which two diploid nuclei fuse, this fusion nucleus upon 
division shows the chromosomes arranged in pairs, and that 
even in those cases of the fusion of four diploid nuclei, the di¬ 
vision of the fusion nucleus still shows the paired arrangement 
instead of a tetraploid arrangement. He concludes from these 
observations that those affinities which are responsible for the 
approximation of homologous chromosomes are satisfied with 
the proximity of two such units. 
He further calls attention to conditions in the endosperm 
nuclei of Galtonia candicans as evidence in support of his con¬ 
clusion that only homologous chromosomes pair. As men¬ 
tioned above, the haploid nuclei of Galtonia contain six large 
and two small chromosomes, and the endosperm nucleus would 
therefore contain twelve large and four small chromosomes 
from the female polar nuclei and six large and two small 
chromosomes from the male nucleus. In polar views of the 
equatorial plate stage Strasburger believes that the. chromo¬ 
somes are arranged to form six pairs of large and two pairs of 
small chromosomes and in addition six isolated large and two 
isolated small chromosomes. (See his Figs. 10 and 11, PL VI.) 
The isolated chromosomes are conceived as remaining separate 
owing to a lack of homologous chromosomes with which to pair. 
Rosenberg (80), investigating hybrids of Drosera longifolia 
X D. rotundifolia,—the former with 40 somatic chromo- 
