296 A CYTOLOGICAL INVESTIGATION OF SOME SPECIES 
„Quite recently a magnificent series of new canes, fully equal to any 
that have brought wealth in the past to the cane-growing countries of 
the tropics, have been discovered in the unexplored recesses of New 
Guinea, a place sufficiently remote to make it practically impossible 
that these could have been derived from India. We are driven then to 
conclude that the thick cane group, essentially different in so many | 
respects from the indigenous Indian ones, has arisen from a separate 
- centre, namely the mountainous islands of the Malay Archipelago and 
Polynesia. It is interesting to note that Saccharum spontaneum is recor- 
ded as indigeneous in many of these islands as well as in India, so that 
we have still the possibility of the species being the ancestor of the 
thick canes. But it seems to the writer probable that, in the absence 
of connecting links, it is more reasonable to assume that the thick ca- 
nes as a group arose rather from an allied species now lost in the wild 
state.” 
Apart from other objections, which could perhaps be raised against 
the opinion, that the British-India varieties. Chunnee and Ruckree II 
should have been derived from S. spontaneum, such a derivation ap- 
pears, cytologically considered, to be very improbable. The possibility 
of an origin of the thick sugarcane-varieties from S. spontaneum by . 
means of mutation, can even be entirely excluded. If Chunnee and 
Ruckree had arisen by means of mutation from S. spontaneum this 
mutation must have been accompanied by a loss of about 20 chromo- 
somes in the somatic cells. An origin of the thick tropical sugarcane- 
varieties from S. spontaneum would even require a loss of 32 chromo- 
somes. Such a diminution of the number of chromosomes is unaccep- . 
table, especially in the case of S. officinarum whose numerous, habi- 
tually very different, forms all possess exactly 32 chromosomes less 
than S. spontaneum .One can imagine however, that daughterindivi- 
duals possess a few chromosomes less than their parents as the conse- 
quence of small irregularities in the reduction-division of those parents. 
We have already considered the possibility of an origin of Chunnee and 
Ruckree from a species with 96 chromosomes in its somatic cells. Ro- 
SENBERG 1) is of opinion, that the Crepis-spécies with 3 chromosomes 
may have arisen from those with 4 chromosomes, by an occasional fai- 
1) O. ROSENBERG. Chromosomenzahlen und Chromosomendimensionen in der 
Gattung Crepis. Arkiv för Botanik. k. Svenska Vetenskapsakademien. Band 15, 
IN eet Se 
