CADET HAND 193 



basitrichs look structurally very much like the much larger micro- 

 basic b-mastigophores we have looked at in the same tissue, the 

 acontia of Metridium. Cutress may be correct in writing "It may be 

 presumptuous to state that the man who defined almost the entire 

 system of cnidae classification failed to recognize his own categories" 

 (ref. 5, page 126), but it seems "presumptuous" to me for Cutress to 

 have done this on what appears to be spurious logic which assumes 

 a shaft, rather than on factual evidence such as the electron micro- 

 scope could have produced. At any rate, the evidence is not in yet 

 and whether most basitrichs, as we have known them from the liter- 

 ature, are in fact b-mastigophores remains to be seen. If Cutress is 

 correct the identification of microbasic b-mastigophores will be 

 much easier than it is today. 



My last comments on Cutress concern his new category of macro- 

 basic p-mastigophores. By definition this category is said to have 

 the undischarged shaft inverted and folded back on itself. This 

 certainly is not so as I noted earlier, nor do I believe that this cate- 

 gory includes the holotrichs of Corynactis as Cutress states. In our 

 Corynactis caJifornica the holotrichs are good isorhizas, that is the 

 thread is isodiametric. The category Cutress proposes would in- 

 clude the former macrobasic amastigophores, and again I would say 

 that the shortness of the thread, if it exists at all, is good reason for 

 keeping the amastigophore separate from the p-mastigophore. It 

 also seems reasonable that macrobasic p-mastigophores do exist, 

 but they differ strikingly in their appearance from the microbasic 

 p-mastigophore which has the obvious long coiled terminal thread 

 within the capsule. 



The comments I have made so far concern both structure and 

 types of nematocysts and I do not intend to review the details of 

 fine structure which are so well known to so many and which we 

 are adding to almost daily as new electron micrographs are exam- 

 ined. The work of Chapman and Tilney (3, 4) stands out as 

 the best work to date on the fine structure of fully formed nemato- 

 cysts, and the work of Slautterback and Fawcett (9) on the de- 

 velopment of nematocysts is clearly the best on this subject to this 

 date. That this elegant work is being done on hydra is little wonder 

 when one considers how easy this beast is to handle in the labora- 

 tory, primarily as a result of Loomis' studies. What are needed are 



