Notes on Recent Literature. 
149 
and Moore, 1 not to an association of the chromosomes in pairs, but 
to the fission of the single chromosomes in preparation for the 
mitosis. 
On the other hand, Cannon 2 found indications of the association 
in pairs of the chromosomes during anaphase of the somatic divisions 
of Pisum. Strasburger has found a similar association in Pisum 3 
during metaphase, in Galtonia and in Funkia . 4 In the last genus 
the chromosomes are of different sizes, and Miss Sykes 5 has recently 
confirmed Strasburger’s observation that chromosomes of similar 
size are associated with one another in the somatic mitoses, as is 
also the case, of course, in the heterotype division. Overton 0 has 
found the paired arrangement also in the cells of the root-tips of 
Calycanthus. 
Unless some very fundamental mistake has been made in the 
observations, it is difficult to see how any interpretation based on 
the lines of that given by Farmer and Moore in the case of the 
Cockroach can be made to apply to such an association of chromo¬ 
somes in pairs in metaphase and telophase. And if such an 
association exists, it is to be expected that indications of it would 
remain when the associated chromosomes become transformed into 
the threads of the resting nuclei. The paired arrangement of the 
threads which Miss Sykes 7 has described in the nuclei of Funkia, 
Pisum, Hydrocharis, Lychnis and Bryonia is, to say the least, 
suggestive in regard to this point. 
In the majority of plants and animals the limits of the individual 
chromosomes are lost in the evenly distributed alveolar or reticulate 
framework to which they give rise in the resting nucleus, and their 
inter-relations are therefore so much the more difficult to trace. 
In 1905, Overton 8 presented evidence that the chromosomes persist 
as recognizable individual structures in the germ-cells of certain 
plants. 9 To these structures he gave the name of “ prochromosomes.” 
His last paper 10 includes some most important extensions of his 
earlier work upon these bodies, by whose means he is able to trace 
the relations of the chromosomes one to another, not only in the 
germ-cells, but throughout the various conditions of rest and division 
through which the somatic nuclei pass. 
He finds that, in Calycanthus and Thalictrum, the prochromo¬ 
somes of the somatic cells are arranged in pairs, connected with 
one another in series by parallel threads of linin, so that in the 
1 Q. J. M. S. 48 , 1905, pp. 528-537. 
2 Bull. Torrey Bot. Club 30 , 1903, pp. 519-543. 
3 Jahrb. Wiss. Bot., XLIV., 1907, p. 489. 
4 Ibid, XLII., 1905, p. 19. 
6 Arch. Zellforsch 1, 1908, p. 392. 
0 Ann. Bot., XXXIX., 1909, p. 45. 
T Op. cit. 
8 Jahrb. Wiss. Bot., XLII., 1905, pp. 121-151. 
0 See also Rosenberg : Flora, XCIII., 1904, p. 250. In the paper 
referred to below (page 39), Overton gives a list of plants in 
which prochromosomes, or corresponding structures, are 
known to occur. To this list may be added Mercurialis. 
>0 “ On the Organisation of the Nuclei in the Pollen Mother-Cells 
of Certain Plants.” Ann. Bot., XXXIX., 1909, pp. 19-53. 
