MUSEUM OF COMPARATIVE 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 satisfactory 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 hematoxylin 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. 
Tho 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 
