THE TROPICS. 
301 
behaviour of discontinuous characters. The statistical study 
of continuous variations has been greatly elaborated during 
the past decade by the Biometric school : for the purpose of 
the present paper, however, it is sufficient to assume such a 
knowledge of “normal ” variability (53), as may be obtained 
from a perusal of Galton’s “Natural Inheritance.” 
In giving an account of recent progress, it appeared that 
interest might be added to the discussion by illustrating it 
with concrete examples drawn from experiments in plant¬ 
breeding which have been carried out by the writer at 
Peradeniya during the past two years. The present paper is 
to be regarded as an introduction to a full account of these 
experiments which it is hoped will appear shortly. An 
indication will also be made here of some of the most impor¬ 
tant results which these experiments have afforded, since at 
the present stage of the inquiry a prompt publication of 
data is desirable even when these differ only in detail from 
facts already known. Work of a merely confirmatory nature 
is also not without value. A few of the facts here recorded 
are new in a somewhat more marked degree. 
To the experiments here described certain necessary 
limitations have been attached. The majority of them were 
concerned in the first place with the acclimatization of plants 
from a more temperate country, and with the production 
from these, by crossing, of strains better adapted to a tropical 
climate. The number of plants found to be suitable for 
these experiments was limited ; and many of those which 
were tried would hardly grow at all. Serious difficulties 
were met with in the attempt to grow several generations in 
the course of a single year, and the majority of European 
plants tested were found to grow well only at one particular 
season. At other times of year unexpected vicissitudes of 
climate were often attended with disastrous results. 
Au account of these effects will appear later, together 
with details of the experiments here briefly summarized. 
At present I need only emphasize the fact that, in spite of 
8(10)04 m 
