
AND SPECIES-HYBRIDS WITHIN THE GENUS SACCHARUM 925 
splitting of these chromosomes 2 X 9a + 2 X 9b + 2 X 9c chromoso- 
mes would occur in the new individual. The reduction division would 
subsequently give rise to gametes with 27 chromosomes. If it should 
be proved by crossing-experiments, that new forms can indeed arise in 
the way imagined by WINGE, one could imagine that S. officinarum 
had arisen from a cross between forms possessing respectively 8 and 32 
chromosomes or of such with 16 and 24 chromosomes in the haploid 
phase, on the supposition that 8 is the basal chromosomenumber of the 
genus Saccharum. The parents of S. spontaneum could then have had 
8 and 48, 16 and 40 or 24 and 32 chromosomes. 
In as much as the hybrids between S. officinarum and S. spontaneum 
are most probably triploid, and are arisen from haploid gametes, one 
has to imagine some kind of indirect chromosome-union to occur in the 
case of these hybrids also. As, in this case, fission of Saccharum offici- 
narum-chromosomes only, has probably taken place and the S. spon- 
taneum-chromosomes took part in the unsplit condition in the pairing, 
the latter must take place in another way than WINGE imagined in 
the case of tetraploid hybrids. 
In the case of these Saccharwm-hybrids one can imagine three diffe- 
rent ways of pairing: 
1°. an arbitrary, but even, number of S. officinarum-chromosomes 
pairs with an equal number of S. spontaneum-chromosomes ‚the remai- 
ning S. officinarum-chromosomes pair with one another, as do the 
remaining S. spontaneum-chromosomes. 
2°. all S. officinarum-chromosomes pair with one another, as do all 
the S. spontaneum-chromosomes. 
3°. 28 chromosomes of the one set of 40 S. officinarum-chromosomes 
pair with 28 S. spontanewm-chromosomes, 28 chromosomes of the se- 
cond set of 40 chromosomes pair with the 28 remaining chromosomes 
of S. spontaneum. The 12 S. officinarum-chromosomes, forming the 
rest of the first set, subsequently pair with the 12 corresponding chro- | 
mosomes left over from the second set. 
As the chromosomes of S. officinarum and S. one are almost 
of the same size, it will be impossible to settle microscopically which 
of the 3 possibilities has been realised. Still the last supposition appears 
to me to be the most probable one, because I cannot imagine why un- 
split S. spontaneum-chromosomes should pair with unsplit chromoso- 
mes of the same set. 
