434 y- N- Krccker, 



Wherever an eiilargeineiit of tiie e(;toderni occurs it lias beeii foiuid 

 in coiinection with the neoblasts and what is likewise of significance 

 the ectoderm in this region stains mucli the same as do the neoblasts. 

 When treated with Delafield's liematoxylin and eosin their cytoplasm 

 lias a purplish liiie and the same is truc of the adjoining ectoderm while 

 that not in the inmiediate vicinity has the normal bluisli tinge. But of 

 course staining reactions are not necessarily of much value. Of greater 

 iinportance is the difference in the character of the ectoderm when 

 the neoblasts are present and when they are absent. The individuals 

 from which figures 2 and 19 liave been taken were botli killed three 

 days after the Operation. There is a striking difference between the two. 

 In Figure 2 the ectoderm has undergone no change and the neoblasts 

 are not present whereas in Figure 19 the ectoderm has been entirely 

 metamorphosed and the neoblasts are present. A significant fact is 

 that the cells of the transformed ectoderm look like the neoblasts and, 

 indeed, the change is so complete that were these cells seen alone 

 they would be immediately considered neoblasts. In the case of the 

 abnormal anal opening we find that the ectoderm is undergoing the 

 characteristic change and again the neoblasts are present (Fig. 21 

 and 22). The nerve is apparently not injured and although the intcs- 

 tine is in contact with the body wall it has been shown that neither 

 the nerve nor the intestine have a stimulating influence. The only 

 constant factor discernable is the presence of the neoblasts. Another 

 interesting condition is illustrated in figure 23. The edges of the wound 

 have folded in for quite a distance forming a long, intestine like tube 

 and the nerve has come in contact with it some distance from the end 

 of the body. On one side of the tube the cytojjlasm of the cells is nor- 

 mal and the nuclei are not enlarged, but on the opposite side the cyto- 

 plas2n is changed, and the nuclei are enlarged in the same characteristic 

 maniier found elsewhere. The neoblasts are collected along the tube, 

 extending from the nerve for some distance toward the anterior end. 

 They are much elongated and are in contact with the tube at the point 

 at which the cells of the tube have been metamorphosed. 



In Order to ascertain the exact relation between the neoblasts and 

 the metamorphosed ectoderm cells numerous individuals from which 

 the intestine had been removed were examined and in many cases a 

 series of camera lucida drawings were made of the area affected. One 

 of these is given in the accompanying text figure. An early stage 

 has been selected since the small number of cells simplifies matters and 

 allows the relation to be seen more clearly. 



