The indivicluality of the chromosomes and their serial anangement, etc. 133 
(1) Complete fusion of homologous idioplasras followed by equational 
divisioii; (2) Partial fusion followed by equational division of fused por- 
tions and a varying distribution of uncombined portions; (3) No actual 
fusion, but mixture of the homologous idioplasmic imits with redistribu- 
tion of the various elements; (4) Rearrangement of entire chromosomes 
as units; (5) Interaction (perhaps Chemical) between non-fusing portions 
of idioplasni; (6) Such a Separation after contact of fusion that “each 
germ-cell receives the pure idioplasm of one or the other parent”. 
It would appear that the various possibilities for exchange and 
mutual influence during synapsis may be sufficient to account for the 
observed facts of heredity without assuming that there must be a chance 
distribution of chromosomes during the heterotypic division. 
The serial association of the chromosomes has a significant bearing 
on the Problems as to the general Organization of the nucleus. Evidence 
against the existence of a continuous chromatic spirem at any stage has 
been brought out by Martins Mano (1905), Gregoire (1906), Overton 
(1909), Stomps (1911) and others. 
Martins Mano (1905) and Gregoire (1906) hold that in various 
species of Ällium, and in Solanum tuberosum and Phaseolus vulgaris 
there is no sphem, either continuous or segmented at any stage of the 
somatic di\dsions. They further hold the \dew that there is no distinc- 
tion between linin and chromatin, but this contention has not been ac- 
cepted, at least as having general significance. 
Overton (1909), however, in his studies of the poUen mother-cells 
of Thalictrum 'purpurascens, Calycanthus floridus and Richardia africana 
finds that the prochromosomes in resting somatic and sporogenous nuclei 
are arranged in parallel pairs with obvious linin intervals, and holds 
that “these heterogeneous spirems probably remain distinct throughout 
the life history of the sporophyte”. In his more recent studies on Podo- 
pliyllum peltatum (1911) he also emphasizes the fact, that whUe the spirem 
of the prophases is not a continuous chromatic spirem, the chromosomes 
are connected by visible linin intervals into a definite spirem. 
Stomps (1911) on the other hand reports that in Spinacia oleracea 
there is no serial alignment of the chromosomes and that the chromosomes 
even pass through synapsis without any evidence of a continuous serial 
arrangement. 
In the older literature conspicuous cases of the presence of a chromatic 
spirem in resting nuclei are reported for the gland cells of CMronomus 
(Balbiani, 1881) and the epithelial ceUs of various other insects (Van 
Gerüchten, 1890). Balbiani even suggests that the spirem arrange- 
