‚AND SPECIES-HYBRIDS WITHIN THE GENUS SACCHARUM 303 
we may mention that from seed, obtained by selfing a single inflores- 
cence of such a hybrid individual, 11000 healthy seedlings were ob- 
tained. 
Hybrid individuals between Saccharum officinarum and Chunnee 
also are frequently quite fertile, but pollen-sterile individuals also are 
rather numerous while quite sterile ones are rare. Hybrid individuals 
from a cross of a particular kind of Saccharum officinarum with Chun- 
nee showed ereater diversity in habit than those between a particular 
kind of Saccharum officinarum with S. spontaneum. The cause is per- 
haps the more pronounced heterozygous nature of Chunnee as compa- 
red with S. spontaneum. In the litterature, hybrids between species 
with different chromosomenumbers are but little known. It is usually 
very difficult to obtain such hybrids; and the number of hybrids obtai- 
ned was always small, frequently no success whatever could be recor- 
ded. Usually such species hybrids are sterile, fertile ones are the excep- 
tion. 
In 1916 Ernst!) writes in the 13th thesis of the 9th Chapter of his 
book: , Bastardierung als Ursache der Apogamie im Pflanzenreich”’: 
„Kreuzungen zwischen Arten mit ungleicher Chromosomenzahl haben 
bis jetzt immer nur zur Bildung steriler Bastarde geführt”. This is 
however an exageration, for it was doubtless known to ERNST that 
fertile hybrids between species with different chromosomenumbers oc- 
cur within the genus Oenothera. From the fact, that he wrote this, it 
follows however that such fertile species-hybrids are extremely rare. 
There is consequently a considerable difference in two respects between 
hybrids of species with different chromosomenumbers in the genus 
Saccharum and such hybrids in other genera e. g. 
1°. such hybrids can be obtained easily and in large numbers within 
the genus Saccharum while their obtention is difficult within other 
genera, and, at the best, gives but few hybrid individuals. 
2°. Within the genus Saccharum, a great part of these hybrids is fer- 
tile in both sexes, an other part is pollen-sterile, while quite sterile ones 
are very rare; in other genera such species- -hybrids are usually sterile, 
while fertile ones, which moreover are usually but partly sterile, are 
rare. 
1) A. Ernst. Bastardierung als Ursache der Apogamie im Pflanzenreich. Eine 
Hypothese zur experimentellen Vererbungs- und Abstammungslehre. Gustav 
Fischer. Jena, 1918, p. 365. 
