63 



fig. 9, /?.) is a membrane representing the proximal 

 portion of the double diaphragm (i.). Near the centre 

 of this is a small foramen. In sections taken immediately 

 after antotomy there is a layer of coagulated blood (b.) 

 on the outer side of the diaphragm. 



The torn edge of the diaphragm in contact with the 

 foramen appears to grow over the latter. Thus, shortly 

 after the autotomy has been effected, there is a continuous 

 membrane or diaphragm covering the broken stump 

 (9 C). This membrane is composed of a single layer of 

 epidermal cells, which is continuous with the epidermis 

 underlying the exoskeleton of the basipodite. On the 

 outer side of the membrane is a layer of coagulated blood. 

 On the inner side of the ectoderm of this membrane, and 

 lying close to it, there appears to be a continuous layer of 

 connective tissue fibres. Miss Reed* describes also the 

 presence of a dense mass of blood cells immediately 

 beneath the membrane. 



Regenerative process. Shortly after autotomy has 

 taken place the cells of the diaphragm begin to degenerate 

 (Text fig. 9, D.). Ultimately there is on the outside of the 

 stump a layer of dead tissue, formed of an outer layer of 

 coagulated blood, beneath which is the layer of degenerate 

 epidermal cells. According to Miss Reed, there is also 

 an inner layer of degenerate blood cells. The dead 

 epidermal cells of the diaphragm become disconnected 

 from the epidermis underlying the exoskeleton of the 

 limb, and this epidermis grows inward beneath the dead 

 outer layer. This takes place from all sides, and the 

 in-growing cells meet in the centre and form a single 



* Unfortunately I did not have access to Miss Reed's paper on 

 the histological processes in connection with autotomy until after rny 

 own observations had been made. My results, in the main, however, 

 bear out the conclusions arrived at in her paper (Bryn Mawr College 

 Monographs, Reprint Series, Vol. V, 1905). 



