i88 3 J 
Eyeless and Blind Animals . 
729 
worms. But these animals rea Ct not merely with such great 
differences as existed in the above experiment, but with very 
slight distinctions. If the experiment was so modified 
that the one window was of clear glass and the other of 
milky glass, there were found in the light compartment 204, 
but in the darker one 326, or a majority of 122. Though 
this difference is not very great, Prof. Graber considers it 
allowable to infer that earth-worms are capable of recognising 
the difference, and would even be able to reaCt upon far 
smaller variations in the intensity of the light. 
In the following experiments on the sensitiveness of earth- 
worms to qualitative differences of illumination the coloured 
lights employed were selected of equal intensity, in order to 
eliminate the influence of different intensity which has been 
shown above. As this is difficult to carry out in practice, 
the experiment was so arranged that in each pair of colours 
first the one and then the other was selected much the 
lighter. After it had been proved that the earth-worms 
were attracted by red, but repelled by blue, in all subsequent 
experiments the blue was chosen much darker than the 
red. In twelve enumerations there were found in the light 
red 193, and in the dark blue only 57 worms, so that the red 
blue quotient = 3*4. If we consider that, as far as the in- 
tensity of light is concerned, the worms would give the blue 
compartment the preference, it is fully proved by these ex- 
periments that these animals are exceedingly sensitive to 
qualitative differences of light. 
A comparison was next instituted between ordinary white 
light and white light from which the ultra-violet rays had 
been eliminated by a passage through carbon disulphide. 
In five enumerations there were found in the white free from 
ultra-violet 87 worms, but in the ordinary white light only 
13, the quotient therefore being 6*6. Worms, therefore, seem 
to have a strong dislike for the ultra-violet rays. 
A comparison between light green and dark blue gave in 
the former 138, as against 42 in the latter, the quotient 
being = 3*3. 
Finally, experiments with light red and dark green gave 
the respective numbers 168 and 72, or a quotient of 2*3. 
We cannot help pointing out how fully these results dis- 
agree with the common notion of the beneficial effects of 
the blue light both upon animal and vegetable life. Our 
readers will doubtless remember a work written by General 
Pleasanton, in which the author recommends blue light as 
a means of promoting the health and vigour of both animals 
and plants, and even of curing certain diseases. M. Yung, 
VOL. V. (THIRD SERIES.) 3 B 
