81 
1914-15.] Regeneration of the Legs of Decapods. 
access to the work of Emmel. The information, however, is useful for 
comparative purposes. Emmel went a step further than Reed when he 
described in detail the morphological side of the replacement of muscle. 
Many other workers have given attention to limb regeneration in 
Crustacea, but their results are of interest more from a morphological point 
of view than from a physiological one, and it is of the latter that this paper 
attempts to treat. They include Ost (8), Zeleny (9), and Haseman (10). 
Methods. 
The observations recorded here were made upon decapod crustaceans 
because this group shows limb regeneration in its highest development. 
Homarus vulgaris (the common lobster), Eupagurus bernhardus (the 
hermit crab), and Carcinus moenas (shore crab) were taken as species 
typifying the process. On the first a straight papilla is grown on the old 
stump. It is invested by a chitinous coating, and is almost a perfect 
miniature of the normal limb (figs. 14 and 16). The hermit crab, on the 
other hand, grows a curved papilla much more stout in proportion to size 
than the lost appendage. In the last-named species the new limb-bud is 
completely folded in and enclosed in a chitinous envelope. In every case, 
as will hereafter be described, the bud suddenly expands to become a limb 
of almost normal size when moulting occurs. 
In the case of the lobster the chelipeds were damaged and subsequently 
autotomised between the first and second joints by the animals themselves. 
The walking legs were either removed directly by the scissors or by 
autotomy at the second joint. Separate tanks were provided for each 
lobster, and the animals were fed weekly throughout the period of 
regeneration. 
Hermit crabs were treated in two ways. Firstly, a series of globes 
were fitted up with siphon tubes and a continuous circuit kept up through 
them. The crabs, thus isolated, were fed weekly. The second method 
employed also kept the crabs under a continuous circuit, but the animals 
were not fed at all during the period of regeneration. Air-tight bottles 
with inlet and outlet tubes passing through rubber corks were connected 
up in series, and in each a crab removed from its whelk shell was placed. 
Confusion on the occurrence of moulting was thus avoided. Legs were 
damaged and autotomised by the animals at the breaking plane. 
Shore crabs required less careful treatment, and on this account were 
placed in a common tank, operated on at one time, and removed at definite 
intervals. 
In addition to those decapods of which the limbs were regenerated 
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