I9 2 HOLMES. [\'OL. II. 



of three joints and a minute terminal fourth joint ; the right 

 one had a flagellum of four joints. 



The Effect of Cutting- the Animal in Two. 



It has been found in many of the lower animals that, after 

 removal of the posterior part of the body, the anterior portion 

 manifests little signs of pain and acts as if no injury had been 

 received. Many interesting cases of this kind have been col- 

 lected by Dr. Norman in his paper entitled " Do the Reactions 

 of the Lower Animals against Injury indicate Pain Sensa- 

 tions?" 1 



In order to see how the removal of the posterior part of the 

 body affects the behavior of Amphithoe, I cut the animal in 

 two just behind the third thoracic segment. In the posterior 

 piece the thoracic legs moved but little, but the pleopods kept 

 up their rhythmical beating for fully a half hour. The anterior 

 part of the animal apparently suffered little discomfort, since, 

 after the operation, it behaved much as if forming a part of the 

 whole organism. The animal lay moving its antennules to and 

 fro and making the usual movements of its gnathopods, just as 

 an uninjured specimen would do. A piece of meat was brought 

 near so that it was struck by the movements of the antennules ; 

 it was first swept a little nearer by the second antennae, and 

 then quickly grabbed by the gnathopods, drawn in, and eaten, 

 although the food could pass through only the small part of 

 the alimentary canal that remained. Since this reaction in 

 the normal animal is readily prevented by fear, and only occurs 

 when the animal is hungry, it is somewhat surprising to find it 

 performed after such a serious injury as the loss of the poste- 

 rior half or more of the body. The animal behaves in such an 

 apparently normal manner after this operation that it would 

 seem as if the loss was scarcely felt. Owing to the loss of the 

 posterior part of the body, many of the actions of the animal 

 are naturally impeded or prevented. It cannot, for instance, 

 get meat except when it is placed quite near, as it is unable to 

 make its accustomed spring out of the nest. But in general, 



1 Am.Jonrn. Phys. Vol. iii, p. 271. 1900. 



