AND SPECIES HYBRIDS WITHIN THE GENUS SACCHARUM 10} 
fectly fertile. It thus became possible to cross hybrids of Saccharum of- 
fieinarum and Chunnee with hybrids of Saccharum officinarum and 
Kassoer, and to cross the products, so obtained, with S. officinarum 
again. In this way very complicated combinations have been obtained. 
The Kassoer-cane has been considered by KRUGER!) as possibly the 
wild ancestor of the sugarcane, JESWIET however is of opinion, that 
Kassoer is a spontenaeous hybrid of Saccharum spontaneum and S. offi- 
cinarum. In the years 1918, 1919 and 1920 namely numerous crosses 
between Saccharum officinarum (sugarcane) and S. spontaneum (glagah) 
have beeen obtained in Pasoeroean, among which many individuals 
resemble Kassoer closely in habit. It is therefore highly probable that 
Kassoer is a hybrid between sugar-cane and glagah, so that all 
Kassoer crosses have to be considered as crosses between the species : 
S. spontaneum and S. officinarum. 
The species-hybrids made by the experimentstation of Pasoeroean 
consequently are built up from Saccharum officinarum, Saccharum spon- 
taneum and Chunnee-cane, the latter being cane which cannot be 
considered to belong to either of the two species of Saccharum men- 
tioned. 
Since 1918 additional crosses have been made between S. officinarum 
and another Saccharum-species, common in the South of China; while 
one contemplates, if possible, to cross all species of Saccharum with one 
another at the Pasoeroean station. It is ofcourse highly desirable to 
have a firm basis for these crosses in the exact morphological descrip- 
tion of all Saccharum species, with which JESWIET is now occupied. Cy- 
tological investigation is of no less importance for the differenciation of 
the species. The last 15 years have shown, namely, that species, belon- 
ging to one genus, frequently differ in chromosome-numbers and that 
these, in many cases form a progressive series. TAHARA ®), for instance, 
found in the gametes of species of the genus Chrysanthemum thechromo- 
somenumbers, 9, 18, 27, 36 and 45. According to HEILBoRN‘) the haploid 
1) W. KRUGER, Das Zuckerrohr und seine Kultur, p. 24. 
2) J. JESWIET, Beschrijving der soorten van het suikerriet. Derde bijdrage. Ar- 
chief 1916, p. 3143. 
3) Masato TAHARA, Cytological Studies in Chrysanthemum. Botanical Maga- 
zine Tokyo. Vol. XXIX 1915, p. 48. 
*) Otto HEILBORN, Zur Embryologie und Zytologie einiger Carex-arten. 
Svensk. Bot. Tidskr. 12. 1918. 
