Life-history and Anatomy of the Appendiculate Distomes. 3g]^ 



According to my own observations, which are very positive on 

 these points, the worm does not lead a predatory life; it does not 

 attack other animals while free-swimming. Those individuals which 

 may be seen within the body- cavity of Copepods have not gained a 

 forcible admittance by breaking their way through the body-wall of 

 their victims. I have determined by means of sections that not 

 only is the body-wall of such Copepods uninjured, but the wall of the 

 entire intestinal tract as well. Those individuals which are found 

 projecting from the bodies of Copepods have not taken hold of them 

 with the acetabulum in order to suck them out and then get inside 

 of them, but they are parasites which have passed through their meta- 

 morphosis inside the Copepod and are now in the act of breaking 

 their way out into the sea-water. 



What WiLLEMOES-SuHM says of the genesis of the appendix is 

 also incorrect. The youngest worms he observed did not, according 

 to his statement, yet possess the "eingestülpten Schwanz" but in the 

 older worms "der Schwanz stülpt sich ein". His observation is correct, 

 in this case, but his deduction is wrong. The youngest worms do 

 not possess a protruded appendix and the older worms do, but that 

 organ has made its appearance in exactly the opposite way from that 

 which he mentions. In the former, the Anlage of the appendix is 

 already present as a sac at the hinder end of the body, which 

 communicates with the outside through a terminal pore, and the 

 appendix first makes its appearance in the older worms when this 

 sac evaginates. 



I conclude, therefore, that Willemoes-Suhm was mistaken in 

 his observations and conclusions in this matter; first, in stating that 

 the young, free-swimming Distome leads a predatory life; second, in 

 stating that it enters the body of the Copepod, while in this stage, 

 by breaking an opening through the body-wall of that animal; third, 

 in comparing the condition of the worm in the Copepod to that of 

 an encysted cercaria; fourth, in his account of the genesis of the 

 appendix. These mistakes are very unfortunate as his observations 

 on these matters are, with the exception of those of Giesbrecht, the 

 only ones on record, and his statements have been frequently quoted 

 and have influenced the views of other authors (see Juel, 1890, p. 8 ; 

 MoNTiCELLi, 1891, p. 23; Braun, 1892, p. 853). 



Giesbrecht (1882, p. 163) also made observations at Kiel and 

 found the same worm as Willemoes-Suhm. I have unfortunately, 

 not had access to his paper, but according to Braun (1892, p. 853), 



