Meiotic Nuclear Divisions of Galtonia candicans. 751 
and numerous, and the space of the nucleus too limited, to allow of the 
threads running parallel to one another throughout their length. He 
maintains that this is a physical impossibility, and that this impossibility 
is increased by the anastomosis amongst the threads themselves. If the 
parallelisms do represent the pairing of homologous parental chromo¬ 
somes, how is the parallelism in parthenogenetic eggs to be explained ? 
( 19 ) (1907). 
Goldschmidt ( 7 , 8) (1905, 1908) has shown that in the heterotype pro¬ 
phases of Zoogonns minis the chromatin becomes collected into a ‘ zwei- 
reihige Lagerung der Kornchen zum Teil schon eine Andeutung der 
spatern Langsspaltung zeigend These behave like ordinary somatic 
chromosomes and go on to the spindle showing their longitudinal fission. 
The reduction takes place at the homotype division ; the somatic number of 
chromosomes, which is ten, segregates into two groups of five. 
Such is the evidence of those who hold that the parallelisms of the 
heterotype prophases are in no way different from those of the somatic 
divisions, that is to say that the parallelisms of the heterotype divisions 
arise from the longitudinal fission of the same somatic chromosome and not 
the approximation of two different somatic chromosomes. If this view is 
the true one then the approximation of the chromosomes, which is a 
necessary act on account of the reduction, must either take place, as 
Overton ( 24 ) (1909) suggests, in the telophase of the last archesporial 
division, or, as many cytologists have thought, during synapsis, or during the 
hollow-spireme and second-contraction stages. 
(3) Finally, there are those workers who do not believe in the existence 
of parallelism, as such, in the heterotype prophases, and when it does occur 
they consider it to be a mere chance or coincidence. They base their 
arguments on the fact that there are often not only two threads running 
parallel to one another, but sometimes three or more. This anomaly may 
partly be explained by the fact that concentration for each somatic 
chromosome is often in the form of the drawing together of a netlike 
arrangement, as diagrammatically shown in the prophases of the nuclei of 
the root. Or it may be that where several threads run close to one another, 
concentration for the formation of the somatic chromosomes is proceeding 
simultaneously with the pairing of homologous chromosomes. 
It seems only possible to settle this difficult question as to the homology 
of the parallelisms of the heterotype prophases by tracing their origin from 
the telophase of the preceding last archesporial division, and in order to do 
that it is essential to secure material in which there is no ‘ rest ’ between the 
premeiotic and meiotic divisions. There is much evidence to show that the 
parallelisms of the somatic and of the heterotype prophases have the same 
outward appearance, so that it is only by studying their origin that the 
truth as to their significance can be arrived at. 
