DAVID B. SLAUTTERBACK 129 



tachment region at the opposite pole from the opercuhim been 

 described in the Hght microscope hterature? Wasn't this interpreted 

 as being important in retracting the tube after it had been formed? 

 I seem to recall something of this sort. I have seen electron micro- 

 graphs of nematocysts that show a specialized area at the opposite 

 end from the operculum. I wonder if you would comment on 

 this? 



SLAUTTERBACK: Yes, I understand that such structures have 

 been described around the outside of the capsule. I have never 

 seen these. 



HAND: Cutress described such a structure inside the microbasic 

 mastigophore in his paper on anthozoan nematocysts, but he did not 

 suggest that it was used to withdraw the thread. 



SLAUTTERBACK: I have never seen anything inside that didn't 

 obviously belong to the tubule itself, and these would be everted 

 with it: spines, thorns, and things of that sort. George, did you want 

 to speak about that? 



CHAPMAN: I was wondering if Dr. Wood was referring to the 

 plug in the basal capsule pore that Kepner and his colleagues de- 

 scribed. 



SLAUTTERBACK: Of the capsule itself? 



CHAPMAN: A dense mass of material which they originally 

 described as being a plug in the pore in the basal portion of the cap- 

 sule. The function of it is not understood. It was thought to be the 

 end of the spiral tube and to be converted to magma just prior to 

 discharge. 



SLAUTTERBACK: Have you seen such a structure? 



CHAPMAN: Yes, I think one of our pictures of a few years ago 

 presented it rather vaguely. 



SLAUTTERBACK: I haven't seen it. 



