SECTIONAL TRANSACTIONS.—I, J. 537 
through this resistance (about 10 m.a.) is sufficient to strike one neon lamp 
and to keep it alight, but when once this lamp has lit the resultant voltage 
between the buss bars is insufficient to strike any additional lamps. Con- 
sequently, when after turning on the main a neon lamp lights, it indicates 
that the switch connected to that lamp was the first to be closed. The 
apparatus can thus be used to ascertain which one of several individuals 
takes the least time to close his switch after a given signal which corresponds 
to the switching on of the main. 
(d) Advancing and retiring colours. 
‘Chromatic stereoscopy ’ (Hartridge, Journ. Physiol., lii, 222, 1918) is 
not limited to coloured objects, for I find that it is possible for black and 
white to be advancing and retiring colours when placed on backgrounds of 
suitable colour. ‘Thus when they are placed on a red ground, black advances 
and white retires ; but when they are placed on a blue ground, white ad- 
vances and black retires. ‘These relative positions may be explained as 
follows : A black object on a red ground is seen in the same position as a 
red object on a black ground would be. A white object on a red ground, 
however, is equivalent to a blue-green object, or a black ground plus a 
uniform red ground without any object on it (as may readily be seen by 
summing the colours). Now a blue-green object on a black ground retires 
relatively to a red object on a black ground and, therefore, substituting the 
equivalents we have just found, a white object on a red ground retires but a 
black object on ared ground advances. Observation shows that a white object 
on a blue ground advances, whereas a black object on a blue ground retires, 
but a white object on a blue ground may be replaced by a yellow on a black 
ground plus a uniform blue ground. We know, however, that a yellow 
object on a black ground advances, whereas a blue object on a black ground 
retires. Therefore we have explained the phenomenon in this case also. 
For grounds of intermediate colour for red and blue, namely yellow and 
green, the phenomenon is not so striking as it is for red or blue. 
AFTERNOON. 
Visit to Leicester Royal Infirmary. 
Tuesday, September 12. 
Joint Discussion with Sections D (Zoology, €8) and K (Botany) on 
Genetics (10.0). 
SECTION J.—PSYCHOLOGY. 
Thursday, September 7. 
Prof. C. W. VaLentine.—The early development of language in the 
child (10.0). 
Evidence based on observations of five children from the first day to the 
age of 3, when all the main forms of language structure have been learned. 
