340° BOTANICAL GAZETTE [MAY 
nal and paternal chromosomes during reduction. This is of 
particular interest from the standpoint of hybrids, but will not be 
discussed further in this connection. 
A striking proof that a redistribution of characters occurs in 
sexual but not in asexual or vegetative reproduction is to be found 
in the case of potatoes. The recent experiments of Easr (3) and 
of SALAMAN (19) show that potato varieties grown year after year 
from tubers usually continue true. But when the flowers are self- 
pollinated the first generation of offspring may show plants of 
different types. Thus a race of potato with red tubers may on 
self-pollination produce sexual offspring some of which bear only 
red tubers and others only white. Here is direct evidence that 
a segregation and redistribution takes place in sexual reproduction 
which is absent in vegetative reproduction, or occurs only in the 
rare cases of ‘‘bud sports,” through the loss of a character. 
The chances for chromosome redistribution during the process 
of segregation in the heterotypic metaphase certainly furnish the 
most probable basis for this segregation and redistribution of 
characters. But as I have pointed out elsewhere (8, p. 211) from 
the evidence of hybrids, this redistribution of characters must also 
occur in certain cases at other points in the life cycle. 
Summary 
Studies of chromosome reduction in different plants indicate that 
there are two general methods of reduction in organisms, one 
involving a telosynapsis or end-to-end arrangement of the chro- 
mosomes, the other involving a parasynapsis or side-by-side pairing: 
The difference, however, is not of phylogenetic significance, because 
both methods may occur in different genera of the same family; 
nor is it of hereditary significance, because the whole chromosome 
must be regarded as the unit of nuclear morphological structure. 
In general, genera having short chromosomes will show telo- 
synaptic pairing, while in forms with long threadlike chromosomes 
the chromosomes are likely to pair parasynaptically. In organism> 
having heteromorphic chromosomes, both methods of pairing may 
occur in the same nucleus. Whether the pairing shall be end-to- 
end or side-by-side is therefore not of phylogenetic or hereditary 
