120 NATURAL SCIENCE. Aug., 



soon as all the animals have in this way been killed and fixed on to 

 the slide, all difficulty is passed. After the Hermann's fluid has been 

 allowed to act for a few minutes it is washed out with water, drawn 

 through in the same way by filter paper, and when well washed, the 

 stain, alum carmine or carmalum, is run in. This should be left to 

 stand for an hour or so in a damp chamber to prevent evaporation, 

 and then washed with water and brought up through the alcohols into 

 oil of cloves, which is finally succeeded by Canada balsam. 



This method, apart from its simplicity and easiness, has the 

 advantage for such forms as Ciliata of preserving cilia, undulating 

 membranes, etc., very well indeed, besides giving good results for 

 the nucleus and internal protoplasmic structures. I do not find it so 

 successful, however, for Amoebae, for which osmic acid or its vapour, 

 followed by picrocarmine or carmalum, gives better results, though 

 more difficult to apply, since the objects do not become fixed to the 

 slide. I have obtained a most beautiful and instructive series of 

 sections through a Pelomyxa which was fixed with osmic acid and 

 stained with carmalum, the sections being further coloured on the 

 slide with various aniline stains. On the other hand, the Hermann's 

 fluid and alum carmine method succeeds very well for AcUnosphsvium 

 and for Gregarines. 



I may mention in this connection that I obtained an excellent 

 preparation of a plasmodium of Badhamia, that was creeping over a 

 slide, in the following way : after fixing with osmic vapour and staining 

 with picrocarmine,5 it was floated on to a coverslip in 30 per cent, 

 alcohol, in a watch-glass, and made to stick to it by drawing off the 

 liquid, in the same way as has been described above for cephalopod 

 blastoderms. Not only was the general form of the plasmodial 

 network well preserved, but the minute structure, especially the 

 nuclei, were beautifully shown. 



I have now described ways of applying this method of a short 

 exposure to Hermann's fluid, followed by a carmine stain, to three 

 very different classes of objects, which may, perhaps, serve as types 

 for yet others. I believe, for instance, that it would prove a valuable 

 method for studying the segmentation of the egg of the fowl, or of 

 other meroblastic ova. The fixing reagent in question was, however, 

 invented by Hermann to be applied to larger objects for a much 

 longer time, in order to study all detail and nuclear figures, just in 

 the same way as Flemming's fluid is usually employed. Hermann 

 originally employed it for the testis of the mouse and salamander, 

 the organ being removed and hardened in toto. I have also obtained 

 very good results, especially as regards nuclear figures, for the testis 

 of the axolotl. Two were removed from an axolotl in October, and 

 placed in Hermann's fluid, one for three days, the other for three 

 months. In the latter the structures were a little darker, but not 



"Weigert's picrocarmine, prepared by Dr. Grubler of Leipzig. 



