io Agnes Robertson. 
the present the consideration of the meaning of the process and 
deal only with the observed facts. 
With minor variations the accounts of the process lately pub¬ 
lished by the Louvain school 1 (Gregoire and his pupils) and the 
Bonn school 2 (Strasburger and his pupils), Charles Allen, 3 and H. O. 
Juel of Upsala, 4 shew a substantial agreement, and the views which 
they hold as to the actual sequence of events seem to be gaining 
ground at the present time. The view held by Farmer and Moore 
differs essentially from that of the observers just mentioned, and 
we will consider the main points of their description later, as well 
as the opinions of one or two other authors. 
The Gregoire-Strasburger view, reduced to its simplest terms, 
may be epitomised as follows. In the mother-cell nucleus as it 
emerges from the resting state the chromosome substance collects 
. into clumps, the number of clumps corresponding to the number of 
the somatic chromosomes. These clumps arrange themselves in 
pairs and then the whole chromosome-content of the nucleus 
contracts to one side of the nuclear cavity. During this contraction 
(known as “Synapsis”) which is not artefact as has been sometimes 
supposed, but can be observed in fresh material, 5 the pairs of pro¬ 
chromosomes are brought into contact. Emerging from synapsis 
they elongate greatly, having joined more or less continuously end 
to end to form a double thread. The second contraction figure then 
sets in, during which the halves of the double spireme fuse to form 
a single thread. On emerging from this second synapsis the 
constituent threads again separate from one another. The double 
thread then segments into half as many lengths as there were 
somatic chromosomes, each of the definitive chromosomes so 
formed consisting of a pair of somatic chromosomes lying parallel 
side by side. In their 1905 publication Strasburger and his 
1 J. Berghs. “ La Formation des Chromosomes Heterotypiques 
dans la Sporogen&se Vegdtale.” La Cellule, T. XXI, 1904 and 
XXII, 1905. 
V. Gr6goire. “La Reduction numerique des Chromosomes et 
les Cineses de Maturation.” La Cellule, T. XXL, 1904. 
V. Gr6goire “Les Resultats acquis sur les Cinfeses de Maturation 
dans les deux Rfegnes.” Premier Memoire. La Cellule, 
T XXII., 1905. 
2 E. Strasburger, C. E. Allen, K. Miyake, and J. B. Overton. 
“ Histologische Beitragezur Vererbungsfrage.” Leipzig, 1905. 
a C. E. Allen. “ Nuclear Division in the Pollen Mother-Cells of 
Lilium canadense.” Annals of Botany, Vol. XIX., 1905. 
4 H. O. Juel. “ Die Tetradcnteilungen bei Taraxacum und 
anderen Cichorieen.” Kungl. Svenska. Vet. Akad. Handl., 
Bd. 39, 1905. 
s E. Sargant. “ The Formation of the Sexual Nuclei in Lilium 
Martagon.” I. Annals of Bot. X., 1896, p. 451; II. Ann, 
of Bot. XI., 1897, p. 195. 
