49 
Pollen Mother-cells of Certain Plants. 
With minor variations the accounts of several zoologists concerning 
the pairing and fusion of the chromosomes during maturation show a sub- 
stantial agreement with those of the above-mentioned botanists. 1 Complete 
agreement of opinion, however, does not exist concerning the manner of 
chromosome association or pairing or the time of fusion or interchange. 
According to most of those authors who advocate an end-to-end union of 
somatic chromosomes, the spirem becomes longitudinally split during con- 
traction stages. Fusion has already occurred. Why the contraction stage 
should be favourable to the longitudinal splitting of the spirem has not 
been made clear. 
There seems to be a tendency on the part of most cytologists to 
consider synapsis as meaning the massing of the chromatin and linin in the 
nuclear cavity, and since there is also entire uncertainty as to when the 
association, conjugation or interchange of influence or material occurs, 
Haecker (’04) has proposed the word Syndesis to apply to the conjugation 
or association of the homologous parental chromosomes. He would also 
use the word Symmixis to signify a chromosome pairing, in which there is 
an actual interchange of chromosome parts if such occurs. 
The massing of the nuclear elements has been found to occur in nearly 
all plants and animals studied with reference to this point. To be sure 
there are some authors in common with McClung (’02, ’05), Schaffner 
(’06, ’07), Janssens (’04, ’05) and Haecker (’07), who still maintain that it is 
either an artifact or else has no significance in the reduction process, but 
the best recent results seem to indicate that it is a natural phenomenon 
associated in some way with the process of maturation of the germ cell. 
In addition to the investigations relating to the Angiosperms synapsis 
has been recently described for several other groups of plants. Cardiff (’06) 
has observed it in Botrychium obliquum , Farmer and Moore (’05) and 
Gregoire (’07) in Osmunda regalis , Yamanouchi ( 08) in N ephr odium molle , 
Burlingame (’07) in certain Ophioglossiales, Farmer and Moore (’05) in 
Psilotum triquetrum , Marquette (’07, ’08) in Isoetes lacustris , Marsilia 
quadrifolia and Equisetum hyemale and Strasburger (’07) in a large 
number of species of Marsilia. Cardiff (’06) describes synapsis in Ginkgo 
biloba and Noren (’07) in Juniperus communis , Farmer and Moore (’05) 
describe synapsis in Aneura pinguis. Among the Algae, Allen (’05) finds 
it in Coleochaete , and Yamanouchi (’06) in Polysiphonia violacea. Black- 
man (’06) and his students in their studies on the rusts find synapsis. 
Harper (’05) and Miss Sands (’07) describe it in the mildews, and Olive (’07) 
has found it in the Myxomycetes. 
1 See among others Winiwarter (’01), Schoenfeld (’02), A. and K. E. Schreiner (’04, ’05, ’06), 
Marechal (’04, ’05, ’07), Marcus (’04), Tretjakoff (’05), Lerat (’05), Bonnevie (’05), Janssens (’05), 
Gregoire and Deton (’06), Schleip (’06), and Van Molle (’07). 
E 
