24O JAMKS ERXEST KINDRED. 



(Fig. 24). The color diminishes laterally and also in the region 

 proximal to the stereom, where the syncytium is trabeculated in 

 the same manner as it is in the prestereomal peripheral areas 

 (Fig. 25). Since the leucocytes were the only cells in the peri- 

 visceral fluid which were observed to be phagocytic and form 

 syncytia it is probable that they aid the prestereomal cells in the 

 formation of the membrane and gradually develop skeletal 

 material for the formation of the stereom. The cytoplasm of the 

 reticulum in the membrane in addition to the carmine particles 

 contains fibers which are probably the remnants of decalcified 

 spicules. The nuclei of the reticulum are round, have a distinct 

 nucleolus and are the same type as are present in free leucocytes 

 observed in the lacunae of the stereom and in the prestereomal 

 trabeculae, so that it is probable that the leucocytes and the con- 

 nective tissue cells of the prestereomal area are of the same series, 

 except that one has become specialized for the production of the 

 stereom under ordinary conditions of growth, whereas the leu- 

 cocytes only take over this function when the body wall is in- 

 jured. The only evidence for a line of demarcation between the 

 two is in the presence of the carmine particles in those cells which 

 make up the reticulum of the membrane. It is therefore evident 

 that the membrane is formed by both the multiplication of the 

 prestereomal connective tissue cells aided by the anastomosis and 

 syncytial formation of the leucocytes which make up the bulk of 

 the membrane. Within the spaces-of the reticulum of the mem- 

 brane are found large numbers of "amcebocytes with spher- 

 ules" which probably carry nutrition to the cells of the syncy- 

 tium, enabling them to carry out their scleroblastic function. 

 These "amcebocytes with spherules" are very few in the region of 

 trabecular formation adjacent to the stereom and are entirely 

 absent from the lacunae of the stereom, thus they seem to be 

 massed in that region where repair is going on rapidly and tin- 

 cells of which are being differentiated . 



Thus in brief there are three regions present in the regenerating 

 area. First, the syncytial region which forms the bulk of the 

 membrane which has closed the opening in the body wall and is 

 composed of a syncytium of leucocytes with small lacuna . con- 

 taining large numbers of "anxrliorvte- with spherules." Sec- 

 ondly a prestereomal area, definitely trabeculated, with large 



