434 THE AMERICAN NATURALIST. (VoL. XXXIII. 
é 
connective tissue.” ‘The liver cells also change sugar into a kind 
of starch. This is soon oxidized in the liver, and heat is produced 
for the use of the body.” And so on ad nauseam. 
Animal Hypnotism.'— The first part of Professor Verworn’s Con- 
_ tributions to the Physiology of the Central Nervous System is taken up 
with an interesting account of the so-called hypnotism of animals. 
As early as 1636 Schwenter described the well-known experiment in 
which a hen is held on a horizontal surface, and a chalk-line drawn 
from her head over the surface; on releasing her, instead of recover- 
ing her normal position, she may remain motionless for some consid- 
erable time. Ten years later Kircher described the same experiment, 
except that he directed that the hen should be bound with a cord > 
_and part of the cord stretched in place of the chalk-line. On drawing 
the chalk-line the cord could be removed, leaving the hen motionless. 
In 1872 Czermak showed that the cord and chalk-line were superflu- 
ous, and that the experiment succeeded perfectly well without them. 
He likewise called attention to similar phenomena in the crayfish. 
The next year Preyer published experiments of a like nature on the 
guinea pig and frog. These were followed by contributions from 
Heubel and from Danilewsky, both of whom worked chiefly with the 
frog. As a result of these studies it was found that many animals, 
chiefly vertebrates, when placed in abnormal positions and held there 
till their struggles to recover had ceased, would remain motionless in 
some cases for an hour or more, especially when they were protected 
against strong sensory stimuli. 
Schwenter believed the animals remained still from fright, and this 
idea was elaborated by Preyer. Kircher thought that the hen, know- 
still. After the removal of the cord she mistook the chalk-line for 
the cord, and, believing she was still bound, made no effort at 
recovery. Czermak, and later Danilewsky, regarded the condition 
as directly comparable with the hypnotic state of the human subject. 
Heubel sought for an explanation of the phenomenon in conditions 
parallel with sleep. 
In dealing with this subject Verworn considers three questions: 
first, what is the pose of the body and the condition of the muscula- 
ture when the animal is “ hypnotized ”? secondly, to what extent is 
1 Verworn, Max. Beiträge sur Physiologie des Centralnervensystems. Erster 
Theil. Die a Hypnose der Thiere. Jena, G. Fischer, 1898. iv + 92 pp- 
and 18 illustrations in the text. 
