12 Agnes Robertson. 
reduction division published by Farmer and Moore 1 differs from 
that just given. These authors use the term “ Maiosis ” or “ Maiotic 
Phase ” to cover the whole series of nuclear changes included in 
the two divisions called “ Heterotype ” and “ Homotype ” by 
Flemming. They say that in the first synapsis a single thread is 
tangled up round the nucleoli. This thread then splits lengthways. 
The split closes again and the second contraction figure sets in, in 
which the thread shortens and thickens. The thread then 
disentangles and arranges itself into a number of loops. These 
loops next break apart from one another so that the nucleus 
contains a number of V-shaped structures in which traces of 
the longitudinal fission can still be detected. Each of these loops 
consists of two somatic chromosomes united end to end. The loops 
finally divide transversely at the apex, and one limb goes to each 
pole. On the way to the pole the original longitudinal split which 
occurred on emergence from the first synapsis reappears, and thus 
is formed the final number of chromosomes destined for the four 
spores. So Farmer and Moore agree with Strasburger and the 
Louvain School in supposing that the heterotype is a mechanism 
for sorting entire somatic chromosomes to the respective poles, but 
they disagree as to the method by which this is brought about. 
The main point on which they differ is that Strasburger thinks that 
the somatic chromosomes make their appearance in parallel pairs 
as soon as the mother-cell nucleus emerges from rest, and that the 
split spireme thread is formed by the end to end union of these 
pairs, whereas Farmer and Moore suppose that the somatic 
chromosomes unite end to end, and that it is the split arising in 
each of these somatic chromosomes which gives rise to the “ split 
spireme.” Thus the longitudinal split in the thread is interpreted 
by Strasburger as the re-separation of the pairs of somatic 
chromosomes which were originally separate but had fused, 
whereas Farmer and Moore regard it as the precocious appearance 
of the longitudinal split which will eventually in the homotype 
separate the daughter chromosomes for the spores. It should be 
mentioned that results agreeing with those of Farmer and Moore 
have been obtained by Lloyd Williams'* for the Dictyotaceae, and 
Gregory 3 for certain Ferns. 
1 J. B. Farmer and J. E. S. Moore. “ On the Maiotic Phase 
(Reduction Division) in Animals and Plants.” Q. J. M. S. 
Feb. 1905. 
2 J. Lloyd Williams. “ Studies in the Dictyotacea:,” Ann. of 
Bot., XVIII., 1904, p. 141. 
3 R. P. Gregory. ‘‘ Spore Formation in Leptosporangiate Ferns.” 
Ann. of Bot., XVIII., 1904, p. 445. 
