Brain Puysiotocy or Worms 861 
area from one which was protected from the light it at once 
turned about. 
Strange to say the reaction-time to light is not markedly 
greater in decapitated angleworms than in normal animals. 
The experimental animals were contained in a dark box in 
which they could without being jarred be suddenly exposed 
to diffuse daylight. Three to eighteen seconds after the 
entrance of the light the decapitated angleworms first began 
to move. It took about the same time in normal worms. 
Lumbricus foetidus lives in decaying straw and manure, and 
it can readily be assumed that the chemical nature of certain 
substances contained in the straw and manure holds the 
animals —that in other words they are positively chemo- 
tropic to the substances. I could readily show that when 
one-half of the bottom of a box was covered with white moist 
filter-paper and the other half with a thin layer of decaying 
straw, the normal worms which were laid upon the filter- 
paper were soon all collected upon the manure. The poste- 
rior pieces of transversely severed worms behave in exactly 
the same way. When they were laid upon the filter-paper 
they were not directly attracted by the odorous substances 
contained in the manure. As soon, however, as they came 
in contact with the manure in their progressive movements 
they crept upon it, and once upon. it they did not leave it 
again. In this way it soon happened that all the brainless 
worms were collected, without exception, upon the manure. 
When they were laid upon a heap of decaying straw, they 
soon buried themselves in it. That was not alone the effect 
of the light, for the reaction occurred also in the dark. 
VII. EXPERIMENTS ON LEECHES 
Tf a leech is cut in two transversely the two pieces show 
entirely different reactions. The wound soon heals and the 
pieces may live a year or more without however, as is well 
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