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Arlow Burdette Stout 
ment may be the normal condition in resting nuclei and that the reti- 
culated appearance commonly observed is an artefact. Flemming (1882) 
in considering this point reinvestigated the nuclei of CMronomus larvae 
and verifies Balbiani’s observations as to the presence of a chromatic 
spirem. He remai'ks that in thesc cases the organization of the resting 
nuclei is very similar to that at the beginning and the end of nuclear 
division. 
Rabl’s (1885) conception of polarity in the nuclei of the Salamander 
is based on the uniform and constant convergence of the spirem loops 
toward the polar field. He clearly shows that although the chromosomes 
give off anastomosing branches there are in the reticulum traces of the 
boundaries of the chromosome loops. He points out that this is evidence 
for the individuality of the chromosomes. A study of his figures shows 
also that the serial arrangement of the chromosomes seen most clearly 
in the spirem can also be traced with considerable clearness in these rest- 
ing nuclei. 
A classical example of the intimate association of chromosomes in 
series is seen in Ascaris megalocephala bivalens. Here there are long 
chromatin rods which behave like individual chromosomes in the germ 
cell divisions, but in somatic divisions each breaks up into about twenty 
Segments which are to all appearances chromosomes. Edw^ards (1910) 
has shown that in Ascaris lumbricoides the so-called sex element of the 
maturation divisions is a group of five chromosomes. Other evidence 
simUar to the above shows that chromosomes may be associated in series 
making what may be called plurivalent chromosomes. The condition in 
Carex aquatilis is somewhat similar in that in the prophases of the reduc- 
tion division the chromosomes are connected up in a homogeneous spirem 
quite as they are in the embryonic divisions of Ascaris. 
Since Strasburger (1905) reported the presence of paired chromo- 
somes in dividing diploid nuclei in Galtonia and Funkia much evidence has 
appeared to show that such an arrangement of the somatic chromo- 
somes is present in many plants. This pairing may be so intimate that 
each pair appears as one double chromosome, a condition shown by Over- 
ton (1909, p. 23). Other cases of constant pairing in somatic nuclei 
have beeil reported, especially by Clemens Müller (1909) in various 
species of Yucca; Rosenberg (1909a) in Crepis virens and (1909c) in 
Drosera; Gates (1911) in Oenothera; Stomps (1911) in Spinacia. 
I shall not hcre discuss the much disputed question of end to end 
or side by side association of homologous chromosomes during synapsis. 
The evidence is, I believe, conclusive that a paired condition is a feature 
