Consctousness tn Plants. 335 
effect, but this is in accordance with the degree of their 
concentration. Unlike what is so natural to plants in gen- 
eral, the Myxomycetes seem to have an aversion to light, as 
shown by their disposition to withdraw from its presence. 
How such tender structures as the Myxomycetes, which 
are destitute of every kind of external protection, are enabled 
to carry on their existence, the knowledge of the remarkably 
delicate reaction of their plasmodia under external influences 
prepares us to understand. Plasmodia, which are not yet 
ripe for reproduction, are kept in the moist substratum by 
their peculiar affection for moisture and utter dislike of the 
light. But within the darkness and moisture of the sub- 
stratum the plasmodia do not necessarily remain in one place, 
for the differences in the chemical composition of the sub- 
stratum cause continual migrations. Nothing more remark- 
able can be said of the plasmodia than that they have a 
wonderful faculty of avoiding harmful substances, and, 
traversing the substratum in all directions, of taking up the 
materials they require for food and growth. When, how- 
ever, their internal changes have advanced so far that the 
plasmodia are approaching the fructifying condition, they 
are brought by their dislike for moisture, which now sets in, 
from the moist ground of forest or wood which they affect 
to the surface, where they creep up various upright objects, 
frequently not doing more than forming rigid reproductive 
capsules at some height from the ground. If, however, the 
substratum becomes gradually colder, as is the case in 
autumn, a change which sets in at the surface moving down- 
wards, then the plasmodia migrate into deeper regions still 
having a higher temperature ; but when the cooling proceeds 
very gradually, which especially happens in large tan-heaps, 
the plasmodia may in their migration attain considerable 
depths, where they then change into sclerotia, which are 
hard tuberous substances, resembling the tubers and bulbs 
of flowering plants. If, however, the temperature begins to 
ascend, the sclerotia again germinate, and movement takes 
