232 
Proceedings of the Royal Society of Edinburgh. [Sess. 
XXIII. — A Comparative Study of the Reflexes of Autotomy in 
Decapod Crustacea. By J. Herbert Paul, M.A., B.Sc. (From 
the Physiological Department of the University of Glasgow, and 
the Marine Laboratories at Millport and Cullercoats.) Communi- 
cated by Professor Noel Paton. 
(MS. received May 19, 1915. Eead June 21, 1915.) 
CONTENTS. 
Introduction . 
Descriptive Parts- 
The Prawn 
The Lobster 
The Crayfish 
Hermit Crabs 
Galatheids 
The Shore Crab 
The Edible Crab 
The Spider Crab 
The Swimmer Crab. 
Discussion and Summary — 
The Nature of the Keflex . 
Degeneration in Reaction Type 
Theories of Autotomy 
Bibliography . 
Macrura 
Anomura 
. Brachyura 
PAGE 
232 
234 
245 
250 
259 
260 
261 
262 
Introduction. 
The self -amputation of limbs, or autotomy, as it has been called, is a 
remarkable example of one of the provisions which marine animals have 
for their survival in the struggle for existence. Many species, especially 
members of the decapod Crustacea, have the power of leaving a leg in the 
grasp of an enemy and escaping to the shelter of a kindly rock. Autotomy 
also occurs very markedly in some echinoderms. 
Without at this point attempting to discuss the nature of autotomy, 
some of its benefits to the animal may here be noted. Since the process is 
found in all its degrees of development in decapods, the remarks here 
specially refer to that group. The group, in addition, presents admirable 
material for a comparative study, because of the great variety of conditions 
under which individual members live. 
Autotomy is a reflex act, simple in some cases and highly complex in 
others, and it is the result of nocuous stimulation of the limb. There is a 
definite breaking-plane or joint at the base of the appendage, and it is here 
that autotomic rupture always takes place. Observation shows that 
