LOCOMOTION IN BATRACHOSEPS. 285 



The animal selected for experimentation was Batrachoseps. 

 This is a small batrachian with a long, slender body and ridicu- 

 lously short, slender legs which, while perfectly functional, are 

 not depended upon to carry on all the work of locomotion. The 

 complete musculature of the body-walls and of the long, slender 

 tail is evidence that they, too, at times assist mightily in locomotion. 

 Indeed in the normal animal one sees that for leisurely movements 

 only the legs are used, the body, always moist and somewhat 

 slimy, being dragged passively along ; and that for locomotion 

 under pressure of unusual excitement the powerful body and tail 

 muscles are brought into play. The body throughout its length 

 is well marked off externally into segments, or metameres. One 

 could not find an animal that combines the locomotor structures 

 of both annelid and vertebrate better than does Batrachoseps. 



There are twenty distinct segments between the girdles of these 

 animals. Of the twenty-two specimens operated upon, the cord 

 was severed between the fifth and sixth segments of some ; 

 between the tenth and eleventh of others ; and of still others, 

 between the fifteenth and sixteenth segments. In a few cases the 

 section was made nearer the girdles, which always resulted in 

 paralysis of the legs. 



They usually recovered from the effects of the chloroform- 

 ether mixture within five to fifteen minutes after taking it. The 

 operation which consisted of simply snipping the spinal column 

 in two with strong fine-pointed scissors, or destroying the nerve- 

 cord by probing with a needle point, took only a minute or a 

 minute and a half. Care was taken to injure as few of the muscles 

 of the body-wall as possible and to avoid puncturing the peri- 

 toneum and the large blood-vessels, excepting in those cases 

 where the animals were cut entirely in two. 



In two specimens a piece of the spinal column about two mm. 

 in length was removed. Shock effects occurred in only a few 

 cases, which will be spoken of later on. 



In all cases where the operation itself was successful and where 

 the cord was not severed too near one or the other of the girdles 

 coordinated movements were observed, not only between the 

 members of the fore-legs and of the hind-legs, but also between 

 the pairs themselves. 



