160 PRESIDENT’S ADDRESS—SECTION J. 
these is fatigue, and if it fail to be recognised and efforts at 
teaching are not at once relaxed, injurious effects are likely to 
be produced. This is why a thorough appreciation of the fact 
of the inseparable connection of mental phenomena with physical 
conditions is of the greatest importance. As to what that con- 
nection is, is quite another matter, and will probably never be 
ascertained. A knowledge of the natural physiological function- 
ing of cells shows that after activity there should come a period 
of rest to allow of the cell recuperating itself. To do this it 
must get rid of the poisonous products generated by its own 
activity, and absorb material to be converted into potential 
energy when the proper time again arrives. If this period of 
rest is curtailed, and the cell is stimulated to a functioning 
before it is ready, an irritable condition is set up as the result 
of malnutrition, which may become habitual. This is seen in 
certain diseased conditions of the nervous system, such as 
epilepsy, hysteria, and some other neuroses. The explosions of 
nerve-cell functioning in these cases take place without due re- 
gard to the proper associated functioning. It is extremely im- 
portant that the delicate, highly sensitive, and actively-growing 
nerve-cells and processes of the child-brain should not be sub- 
jected to such unhealthy stimulation. In natural fatigue the 
gemmules are in a state of extension and sluggish, and ought 
to be left alone. Experiments on animals go to show that if 
this is not allowed, but persistent stimulation is continued, that 
a condition of pathological fatigue is produced, proving ulti- 
mately fatal to the animal. In this pathological fatigue the 
gemmules entirely disappear, and the mental result is the 
stupor sometimes seen as a sequela of continued active delirium. 
This condition has been demonstrated by fatiguing mice by 
persistent stimulation, and comparing their neurons and den- 
drites with those of mice killed in an ordinary manner. It was 
found in the pathologically-fatigued mice that the gemmules had 
disappeared, whilst spherical thickenings occurred in the ramifi- 
cations of the dendrites themselves, especially towards their ex- 
tremities. Further confirmation of this opinion has _ been 
obtained by the examination of the neurons and processes of 
brains which have been subjected during life to the poisonous 
action of certain drugs, such as alcohol, morphine, and potassium 
bromide. In medicinal doses these drugs produce much the 
same effect as is seen in natural fatigue, namely, extension and 
sluggishness of the gemmules. According to Lugaro, this is 
“the attitude of repose—that is, of greatest expansion—contacts 
are multiplied, the nervous processes become more and more 
dispersed and incoherent, the associations become enormously 
diffused, the stimuli subside without provoking reaction, and 
then results the unconsciousness of sleep.” Hence these drugs 
are largely used as hypnotics. The appearances after fatal 
