MUSEUM OF COMPAEATr\rE ZOOLOGY. 137 



passage of most fluids. It shows, further, a strong tendency to curl in 

 the killing fluid, thus rendering it less -serviceable for section cutting. 

 There is no reagent which does not in some cases produce a collapse of 

 the body wall and consequent distortion or maceration of the internal 

 organs. No reagent gave uniformly good results; the best were (1) a 

 saturated aqueous solution of corrosive sublimate, and (2) Perenyi's 

 fluid, heated to a temperature of about 60° C. Picro-nitric acid gave 

 nearly as good results. The curling of the specimens may be largely 

 prevented by straightening the worm gently with the fingers, and drop- 

 ping it suddenly into the warm killing reagent. Flemming's chrom- 

 osmic-acetic mixture made the material very brittle, even after subse- 

 quent treatment with Merkel's fluid, and is not to be recommended. 

 Material preserved simply in alcohol, however carefully, is useful for 

 little more than topographical work. 



Burger mentions the difficulty experienced in staining the material 

 satisfactorily, and I agree with him fully. I experimented more than 

 a month before obtaining a really satisfactoiy method of preparation ; 

 it may therefore be advisable to review the methods employed. The 

 only carmine solution of those (8) tried which will stain it at all is 

 Mayer's hydrochloric acid carmine, and this only after prolonged immer- 

 sion. All hsematoxylin solutions stain it fairly well, but require more 

 time than usual. Bohmer's and Ehrlich's give brilliant results, but on 

 the whole the latter is more reliable and can be highly recommended. 

 The results obtained by Pfitzner's safranin are also good, and various 

 aniline dyes are nearly as satisfactory. 



In embedding in paraffin it is necessary to keep the temperature low. 

 Series cut in paraffin of 50°-52° C. were in all respects most successful. 

 The infiltration must be complete, but a long immersion in paraffin 

 renders the objects very brittle. 



Maceration was tried on preserved material with little success. 



Great assistance was derived from the study of portions of the body 

 cleared in clove oil before staining. Only in this way was it possible to 

 obtain a clear idea of the structure of the two ends. 



II. Systematic. 



Since none of the previous observers have given an accurate descrip- 

 tion of the female, if indeed it has been seen at all, and since a more 

 extended study has modified some of the points given in the original 

 description of the genus and species, I have determined to restate here 



