210 The British Association in South Africa. 
terised by differences of climate, native vegetation, and the crops 
it is capable of producing. 
Professor Potter gave an account of some experiments which 
prove that a certain soil bacterium has the power of slowly decom¬ 
posing amorphous carbon, with the evolution of C0 2 . He sug¬ 
gested the possibility of the carbon at present locked up in our 
coal fields being rendered available for plant-life without the inter¬ 
vention of direct combustion. 
Dr. Horace Brown read a paper on “The Dissipation of 
Absorbed Solar Radiation by Xerophilous Plants.” The author 
discussed first the case of ordinary foliage leaves, and pointed out 
that such leaves may be subjected to intense solar radiation without 
acquiring a dangerously high temperature, because a large propor¬ 
tion of the heat absorbed is utilized in the vaporization of the 
water of transpiration. But in the case of xerophilous plants, 
transpiration is at a minimum, and some other safety valve is there¬ 
fore necessary. Dr. Brown maintains that this is to Jbe found in 
the loss of heat due to thermal emission. Experiments were 
conducted (in collaboration with Dr. Wilson) which resulted in the 
obtaining of a numerical expression for the thermal emissivity of 
the leaves of several species of plants. The results show that in 
this emission of heat from the surface of leaves, a sufficiently 
powerful cooling effect is produced, to prevent the undue heating of 
plants, even when exposed to strong solar radiation under arid 
conditions. 
Mr. R. P. Gregory gave an interesting paper on “ Some of the 
Problems of Heredity.” Having discussed the general principles of 
Mendelian Inheritance, Mr. Gregory described some experiments 
conducted by Mr. Bateson and himself on the genus Primula , in 
which the character of heterostyly was found on the whole to con¬ 
form to Mendel’s Law—the short style being dominant, the long 
recessive. 
In the afternoon Mr. I. B. P. Evans read a paper on “ Infection 
Phenomena in the Uredineae,” and Dr. Schonland one on “ South 
African Succulents.” Papers were also contributed by Dr. G. 
Potts and Mr. J. Medley Wood. 
Thursday was devoted to excursions, chiefly to Pretoria and 
the neighbourhood. A number of botanists visited, during the day, 
the Government Experimental Grounds near the town. Mr. Burtt- 
Davy is here carrying on an extensive series of tests with introduced 
seeds, etc., chiefly of grasses and other fodder plants. An 
