10 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
the unfortunate human being with an incoordinated or improperly 
balanced nervous system into committing crimes against himself or others. 
The germs of resistance to stimuli, or rather of reacting so as to alter 
strength of stimuli, must be present in all living creatures, or life and 
continuance of the species would speedily become impossible; and it 
appears to me that denial of this would be nearly as great an error as the 
view which appears to be held by some opponents of the advance of 
physiological science, that all organisms and animals are about equally 
sentient to stimulation and to pain. 
The experiments conducted with organisms under different coloured 
elasses, described below, in which the relationship of the two halves of the 
dish to the direction of the incident ght was identical, also show, from 
the selection of one-half of the dish by the organisms in preference to the 
other, that the organisms seek that region where the light activity 
possesses an optimum for them although there 1s nothing in the incident 
direction of ight to lead them to swim under one particular glass as a 
result of orientation. 
The same is seen in the experiments of Oltmann! and of Holt and Lee, 
in which a range of varying intensity of light was arranged by means of a 
prism placed along the long side of a long glass trough containing 
organisms. The incident light came in varying intensity perpendicu- 
larly through the prism, and the organisms were then found to place 
themselves in certain intermediate positions where the intensity of light 
suited their optimum, although they had to move to this position 
practically at right angles to the direction of incidence of the light. 
Experiments were made in the present series of observations upon the 
velocity with which the organisms moved in light of varying intensity, 
and also under glasses of varying colour, and it was found that within 
the limits of the experiment, the velocity of movement was practically 
constant, thus showing that the chemical reactions set up by the light did 
not affect the locomotor organs. 
