1^8 E. H. HARPER. 



region. There is probably a close similarity in the physiological 

 processes connected with fission in the two groups. 

 5. Disorganization in the region behind a cut surface. 



() There are a number of phenomena taking place internally 

 during regeneration which can be plainly seen, owing to the 

 transparency of these animals. When a portion of the head 

 segment in front of the eyes is severed, in almost all cases the 

 pigmented portions of the eyes are found later in a fragmented 

 condition and the black pigment cells scattered through the 

 pharyngeal region (Figs. 2, 5, 1 1). This does not seem to be a 

 direct mechanical effect, since it occurs when the eyes are ap- 

 parently not directly injured by the mutilation. This observa- 

 tion, which may seem of slight importance, is mentioned as show- 

 ing how organs behind the regenerating region may be affected, 

 apparently disorganized, in this case, and later restored. The 

 eyes are reformed subsequently and the scattered pigment cells 

 disappear. In Figs. 5 and 1 1 the eye appears in two parts. It 

 became normal later. The interpretation, if such it may be called, 

 which would seem to be indicated by the facts, is that the region 

 just behind the cut surface tends to return to an embryonic or 

 disorganized condition as the result of change in physiological 

 conditions. 



() Another observation of a like nature has been made in the 

 case of the regeneration of the whole pharyngeal region. During 

 the regeneration numerous brown pigmented cells, similar to the 

 chloragogue cells of the stomach-intestine, are seen floating in 

 the ccelomic fluid. These are different from the normal unpig- 

 mented coelomic corpuscles. As was pointed out above, the 

 region behind the cut surface is a seat of regulative activity, the 

 oesophagus and crop being produced in that region by regulation 

 of the intestine. The free pigment cells may be a product of the 

 disorganization of the intestine immediately behind the cut sur- 

 face, as in the case of the pigment cells of the eye. 



As stated above, these two observations seem to indicate that 

 the organs just behind the cut surface tend to return to an em- 

 bryonic condition similar to that of the new proliferated material. 

 This breakdown of tissues may also be comparable to the loss of 

 cell boundaries and return to a syncytial condition in the well- 



