HELIOTROPISM OF ANIMALS 85 
XIV. ADDENDUM: SOME FURTHER EXPERIMENTS ON THE 
GEOTROPISM OF INSECTS 
As I have several times had occasion in this volume to 
mention the influence of gravity on the orientation of ani- 
mals—a subject which in this form has not yet been discussed 
in physiological literature—it may perhaps be desirable to 
add a few further facts on animal geotropism. I must say 
beforehand, however, that my experiments in this field are 
not yet completed, and that I intend to return to this sub- 
ject. 
1. I have found that caterpillars (for example, Bombyx 
neustria) when placed in a hollow vessel creep vertically 
upward. When we wish to pour such caterpillars out of a 
vessel, we employ a method opposite to that used in pouring 
out a liquid ; we must hold the mouth of the vessel upward. 
When such caterpillars are contained in a glass vessel, the 
diffuse daylight entering from above in itself would bring 
about this effect; I therefore made this experiment in 
wooden vessels. When the opening of the vessel was 
directed downward the animals crept upward, and not an 
animal escaped from the vessel. Geotropism, however, like 
heliotropism, is especially evident only at certain epochs in 
the life of the animal; for the geotropic experiments were 
not at all times successful even in the same animals. 
2. Small beetles, particularly Coccinella, which can always 
be procured with ease in great numbers, were placed in a 
wooden box, and to protect them from the effects of light I 
put the box in a dark closet. The animals, which were at 
first scattered over the whole box, were found the next day 
collected at the highest point in the box, on the upper side, 
where they remained. When I turned the box about, they 
changed their orientation and moved again to the top. The 
behavior of Coccinellide and other beetles (particularly leaf 
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