No. 6.] THE CESTODE MONIEZIA EXPANSA. 287 



direction, and if growth of the parts continued, the receptacle 

 and the oviduct from the pore would meet. In brief, this set 

 of organs shows what is practically the normal orientation, 

 while lb' and c" do not. 



The suggestion which offers itself in this connection is that 



o o 



the abnormal orientation of the organs c" and lb' is correlated 

 with the presence of the furrow which lies between them. The 

 furrow is on the ventral side, as are these organs. May it not 

 be possible that the orientation of these two sets of organs 

 with respect to this furrow is due to its extreme depth ? They 

 are oriented with regard to it as if it were the edge of the body, 

 though no pores appear, opening into it. There is a consider- 

 able extent of free surface in the dorso-ventral plane on the 

 sides of the furrow. The organs at c" are far from the real 

 edge, but near this abnormal furrow, and their abnormal 

 orientation appears to be a form of adaptation to the abnormal 

 conditions. The complex of organs lb', as described, is cor- 

 respondingly oriented with regard to the furrow /. The 

 question at once arises as to why this should be, since this set 

 lies at the normal distance from the real edge. The answer to 

 this question may lie in the fact that the left edge of the seg- 

 ment b and the region near it are very short --apparently too 

 short to allow a pore and ducts to appear. The organs at /// 

 are much nearer to the furrow f than to the edge, and if the 

 orientation of c" is determined by the furrow, that of lb' may 

 be also. In the organs c' orientation and position are ap- 

 parently normal. The pore lies rather far anteriorly, and this 

 is probably due to the fact that c is incompletely separated 

 dorsally from the segment next in front. The position and 

 orientation of this set of organs may seem to be strong evi- 

 dence against the conclusion that the orientation of c" and lb' 

 is due to the presence of the furrow / , but here the edge is 

 normal and the proglottid is of normal length, i.e., normal 

 relations are possible here, while they are not in the cases of 

 lb' and c". Furthermore, on the right of b, where the furrows 

 are both normal, and the edge is wider than at the left, the 

 organs are normally oriented and a pore is present, though the 

 parts are not connected. 



