METHOD OF CELL DIVISION IN MONIEZIA 133 



stain black with certain dyes. This is a serious drawback to the 

 use of osmic acid fixatives, for the chalk bodies are so numerous 

 as to obscure much of the development of the reproductive 

 organs. 



The remarks concerning Hermann's apply with equal force 

 to Flemming's although the latter gives a somewhat more 

 nearly perfect fixation considering the tissue as a whole. For the 

 cuticle Flemming's gives better results than any other reagent 

 I have tried. 



My experiments with corrosive sublimate in aqueous solution 

 have proven a complete failure. Circumstances connected with 

 the experiments were such, however, that I am not disposed to 

 regard my results as typical; had I not already had a great 

 number of successful preparations I should have given it further 

 trial. 



With formol-sublimate I have obta : ned good preparat ons. It 

 gives quite good nuclear and cytoplasmic fixation as well as a 

 very fair preservation of the parenchyma. Nuclei and cytoplasm 

 stain dark after it; chromatin is well fixed but achromatic struc- 

 tures are not easily differentiated owing to the homogeneous 

 condition of the nuclei ; cytoplasm, too, is of a dense homogeneous 

 nature not unlike that of certain nerve cells. Calcareous bodies 

 are not present in sublimate material. Formol-sublimate is, 

 however, a good general fixative for Moniezia. 



Picro-sulphuric, while giving somewhat better results than 

 aqueous sublimate (the young embryos are fairly well preserved) 

 is also a failure. It gives a better fixation of the parenchyma 

 than of other tissues. 



There yet remain the Zenker solutions. These give the best 

 fixations, and of them the modification by Dr. King is the most 

 satisfactory of all the fluids I have used on Moniezia. I find, 

 too, that I am able to get better staining reactions on the material 

 fixed in this solution. My study has been made chiefly on this 

 material but I have in every case compared the results with those 

 of the other fixatives. The fixations by chrom-oxalic, Hermann's, 

 formol-sublimate, and King's solution all depend on different 

 actions; therefore, it would seem that the phenomena common 

 to these four reagents cannot be viewed as artifacts due to 

 fixation. 



