432 . BIOLOGY. [Book ti. 



trongon, still supported upon its four feet, resists the impulsions 

 by wMcli we try to overturn it, rises up and resumes its equili- 

 brium if we overcome tbis resistance, and at the same time, by 

 the trepidation of the wings and elytra, testifies a lively feeling 

 of anger, as it would during the integrity of the animal, when 

 provoked by being touched or threatened. But this posterior 

 trongon contains a considerable part of the chain of ganglions. 

 We can carry on this experiment in a more striking manner : 

 the long corselet, which has been detached from the other seg- 

 ments, contains a bi-lobed ganglion, -Brhioh sends nerves into the 

 arms or anterior feet, armed with powerful claws (snatching 

 feet) ; let the head be detached, and this isolated segment will 

 live nearly an hom* with its single ganglion ; it will agitate its 

 long arms, and is quite capable of turning them against the 

 fingers of the experimentalist ■W^ho hold the trongon, and seizing 

 them so as to inflict pain. This single thoracic, or derie gang- 

 lion, then, feels the fingers which press the segment to which 

 it belongs, recognises the point by which it is lield, wishes to 

 free itself from it, and directs towards it the members which 

 it animates."-"^ 



At first sight, the experiment of Dugfes seems decisive ; but 

 the co-ordination of the movements, their apparent intention, do 

 not necessarily prove that they are conscious. Many very com- 

 plicated reflex, but perfectly unconscious movements co-ordinate 

 perfectly. We observe many of these apparently voluntary 

 movements, even in the vertebrated animals, and even in the 

 mammifers, where nevertheless the coalescence of the nervous 

 centres is incomparably greater. A fish, or a frog, deprived of 

 the brain, still executes a series of movements, apparently com- 

 bined. It was the same with the pigeons whose brain Plourens 

 had removed.^ Finally, reflex, co-ordinate movements still take 

 place in a decapitated human corpse. The spinal marrow seems 



1 Dugfes, Physiologie ComparSe, p. 337. 



' Flonrens, Secherches Exptrimentales sur les Propriitis et Us Fonctions 

 du Syst&me Nerveux, &c., Paris, 1824. 



