320 REPORT OF THE CONFERENCE ON GENETICS. 
As a result of the previous work done in breeding sugar-canes, 
it is now obvious that a class of canes has been produced that possess, 
to a large extent, qualities that enable them to resist certain classes 
of disease. Most of the newer seedlings possess a thicker cuticle than 
the older varieties, and are, therefore, more or less immune from the attacks 
of insect pests; and possibly some physiological reaction within the plant 
enables it to withstand the attacks of certain fungoid diseases. More, 
however, requires to be done in this direction, for the root disease, for 
instance, is one which does a considerable amount of damage in the West 
Indies, Hawaii, and elsewhere. In Java it is held that a larger yield of 
sugar depends upon the cane possessing an increased vigour and also 
greatly upon immunity from disease, and therefore breeding for resistance 
to disease is one of the first points to be aimed at. 
The tonnage of cane per acre is especially a point of great import- 
ance. In 1902, Harrison reports that “the results confirm those of 
previous experiments, that neither the addition of phosphoric acid, of 
potash, or of lime to the manures favourably affects the sugar-contents 
of the juice of the canes. The effects of nitrogenous manurings appear 
to be to somewhat retard the maturation of the canes, and thus the 
juice of canes manured with them is, as a rule, not so rich in saccharose 
as is that of canes grown without manure. But this effect is far more 
than offset by the larger yields of produce resulting from the applica- 
tion of nitrogenous manures and by the fact that the increases produced 
by the nitrogen are principally due to the development of the stalks in 
length and in bulk, and not to abnormal increases in the amounts of 
tops and leaves or the production of new shoots to the stool.’’ Watts‘ 
and Cousins have shown that different manures influence greatly 
the yield of crop per acre without appreciably altering the saccharine 
richness of the juice. Moreover, Cousins,§ Jamaica, holds that “ beyond 
a certain point—24 per cent. saccharose in the juice—any increase 
in richness involves a reduction in agricultural yield.” He also 
believes that “the line of development of the sugar-cane as a cultivated 
plant lies primarily in the direction of increased tonnage of cane, and 
secondarily in that of greater purity of juice.” 
As only a few of the varieties now under experiment possess over 
20 per cent. saccharose in the juice, maximum productiveness has not been 
obtained ; but nevertheless it would appear that disease-resistance and a 
larger tonnage of cane per acre, both of which depend largely upon 
increased vigour of the cane, should receive first attention. 
With the view of obtaining some clue to the more prominent characters 
of the different varieties in Barbados, several arrows or inflorescences were 
bagged separately before they were ripe to ensure self-fertilisation, and 
many seedlings have been obtained. As the varieties chosen were hybrids, 
the records of this second generation should give, on analysis, results that 
will be of assistance in the subsequent hybridisation work, for the 
splitting of the different characteristics has been carefully noted. 
Many of the previous records of work on the raising of seedling canes _ 
show that some varieties possess striking dominant characters, which are 
transmitted to their offspring. Kobus® states that “in some cases the 
fecundating power of the pollen of the Chunnee variety is so strong 
