46 BOTANICAL GAZETTE [JANUARY 
merits of parasyndesis and metasyndesis. Granted that the 
chromosomes are fully formed, so far as the arrangement of con- 
stituent parts is concerned, at the time of synapsis, there need 
be no difference in the ultimate result whether the homologous 
chromosomes appear in the spireme side by side or one ahead of 
the other; in either case the paired chromosomes are adjacent and 
are not prevented by their previous arrangement from exhibiting 
the same relations from diakinesis through succeeding stages. 
JORDAN (20) suggests that both parasynapsis and _telosynapsis 
may occur in the same prophase; that is to say, the “end to end” 
arrangement of chromosomes in the spireme is frequently followed 
by a pronounced loop formation, resulting in a parallel approxi- 
mation of chromosomes. On the other hand, parasynapsis may 
be followed by fusion of the ends of paired chromosomes (diakine- 
sis). GATES (15) explains the appearance of both types of con- 
jugation from a mechanical standpoint. According to his view 
short chromosomes are particularly adapted to telosynapsis, while 
long chromosomes are parasynaptic. 
The extension of the theory of chromosome pairing to cover 
the entire sporophytic phase is supported by the observations of 
several investigators. STRASBURGER (39), in a study of the root 
tips of Piswm, found many cases where the chromosomes were 
grouped in pairs on the nuclear plate. He concludes that the 
parental chromosomes in the nuclei of the sporophyte generation 
do not form two separate groups, but that the homologous chromo- 
somes occur in definite positions with respect to each other. He 
also figures a similar condition in an integument cell of the ovule 
of Lilium Martagon (StRASBURGER 40). Miss SYKES (42) describes 
a paired arrangement of chromatic elements in the somatic nuclei 
of Hydrocharis Morsus-ranae and Bryonia dioica. Lychnis dioica 
and Sagitiaria montevidensis show fully formed chromosomes lying 
in pairs. OVERTON (34) states that, in the somatic nuclei of plants 
which he has studied, definite chromatic bodies were visible lying 
in pairs (Campanula grandis, Helleborus foetidus, Thalictrum pur- 
purascens, Calycanthus floridus). BONNET (4), however, finds no 
satisfactory evidence of pairing in the diploid nuclei of the Yucca, 
although he finds definite chromosomes. 
