1914-15.] Regeneration of the Legs of Decapods. 
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DESCRIPTION OF PLATES. 
Plate I. 
Fig. 1, Longitudinal section through the region of the breaking plane of the hermit 
crab’s leg, photo, x 50 diars., showing how the diaphragm stretches across the limb 
cavity before autotomy. This section is not through the region of the foramen, 
and therefore the diaphragm stretches completely from epidermis of one side to 
epidermis of the other. Diaphragm formed by the union of cell processes from the 
epidermis of either side {d). Cells of the epidermis with processes running into 
the limb cavity (e). Chitinous and calcified layers outside the epidermis (c). 
Fig. 2. Longitudinal section through basi-ischium of normal limb at the region 
of the breaking plane, photo, x 50 diars., showing the lower flap of diaphragm {d) 
passing upwards to the nerve {n) and turning inwards along its course, forming a 
sheath or funnel (/). 
Fig. 3. Longitudinal section through the limb-stump of a hermit crab two 
minutes after autotomy, photo, x 66 diars., showing anatomy of structures behind 
the diaphragm {d). Retracted artery dilated with blood serum {a). Extravasated 
blood behind the diaphragm (h). Branch in longitudinal section showing bifurca- 
tion (h Is). Smaller branches, cut obliquely {h os). The same in transverse 
section now at the region of the epidermis (e), and passing beneath it {h ts). 
Fig. 4. Longitudinal section of limb-stump fifteen minutes after autotomy, 
X 66 diars. The nerve (n) has now retracted from the funnel which it occupied. 
The flaps of diaphragm (/' and /") forming this, are forced together at (v) by 
extravasation of blood (5), from the artery, and by disturbance of the balance of 
pressure in the region of the diaphragm. This valvular mechanism prevents loss 
of blood when autotomy occurs. 
Plate II. 
Fig. 5. Longitudinal section of limb-stump fifteen minutes after autotomy, from 
the same series as section in fig. 4, x 66 diars. The pressure in branches from the 
artery shown in fig. 3 (6 ts) has been raised, and blood is extravasated outside the 
epidermis (b), and beneath the chitinous and calcified layers {i). The epidermis (e) 
is now hanging free in the cavity of the stump, and the end of the layer thus 
freed grows over the stump. 
Fig. 6. Longitudinal section through a limb-stump five days after autotomy, 
X 50 diars., showing the beginning of regeneration. The free layer of epidermis 
(fig. 5, e), has sent out a chain of cells from either side (P and 1"). These are 
beneath the old diaphragm (d), and the crust of blood-clot formed outside it. 
Fig. 7. Longitudinal section through limb-stump twelve days after autotomy, 
X 66 diars. The new layer (1) is now complete, and the old shrivelled diaphragm 
(d) is seen outside it ready to be cast off. (d') is the upper flap of the new diaphragm 
growing backwards, parallel to the epidermis. The lower flap (d") grows upwards to 
the nerve which is not seen in this section, and forms the new nerve foramen (nf). 
A virtual limb-cavity (yc) is thus formed between the layer of cells (1) and the new 
diaphragm, and this expands gradually to form the hollow papilla. 
