158 SUMMARY OF CURRENT RESEARCHES RELATING TO 



30 grams water, and 15-20 drops pyrogallic acid. The preparation 

 assumes a brownish-grey colour. It is specially suitable for photo- 

 micrographic purposes, because, when united with albuminous tissues, it 

 undergoes no further change. 



Benda's Modified Copper-haematoxylin.* — Dr. G. A. Tiersol calls 

 attention to tbc excellence of this reagent ; though the method is 

 troublesome the results amply repay where a careful study of cells under 

 high powers is proposed. 



Tissues treated with chromic acid or Fkmming's solution stain 

 readily, as well as do those hardened in alcohol or any other of the usual 

 fluids. For careful examination, staining after cutting is advised ; the 

 sections on the slide or cover are placed for 8-12 hours in an almost 

 saturated solution of cupric acetate (to which a few drops of acetic acid 

 may be added) in the oven at 50° C, washed a few minutes in two 

 changes of distilled water, and stained with 10 per cent, alcoholic 

 solution of hsematoxylin until very dark blue ; transferred directly to 

 hydrochloric acid solution (1 : 350), where they remain until bleached to 

 a straw tint ; after being rinsed in water they are placed in fresh copper 

 solution until again blue. Should the sections be too dark they may be 

 again bleached in the acid and passed through the copper solution as 

 before ; if too pale they are placed again in the hreniatoxylin and carried 

 through the solution as at first. 



The advantages of the method are certainty of good results after 

 chromic acid, control of the intensity and ease of correcting faults of the 

 stain, and above all, the excellent results. "While the colour is less 

 brilliant than the usual alum-hasmatoxylin stainings, the crisp, sharply- 

 defined pictures furnished leave little to be desired, and to those seeking 

 a precise and reliable stain after Flemming's solution this method is 

 confidently recommended. Since the hematoxylin with care and 

 occasional filtering may be repeatedly used, and as the copper solution is 

 readily prepared and inexpensive, the method will be found economical 

 and by no means as complicated in practice as on paper. 



Action of Staining-t — Dr. M. C. Dekhuyzen holds, in opposition to 

 Griesbach,^ that staining is rather a physical process, as in the majority 

 of cases only molecular combinations take place. He classifies the 

 tissues (material hardened in 9G° alcohol) as follows : — Mucin, primitive 

 cartilage capsules (Ranvier), gland cells of fundus, cells of pyloric glands, 

 Neumann's pericellular substance in cartilage, an imperfectly known 

 constituent of nerve, and Henle's layer of the internal sheath of the 

 hair-root are basophile, that is, possess an inclination for basic and a 

 disinclination for acid dyes. The " acidophilous " constituents of tissues 

 show the opposite behaviour, protoplasm especially, in covering cells 

 (" Belegzellen ") and in the lunules of Gianuzzi, connective-tissue 

 bundles, elastin, decalcified bone, muscle, axis-cylinder, the peripheral 

 layer of cartilage where the cells are flattened, and the secondary capsules 

 of Eanvier which lie immediately upon the cartilage cells. Chromo- 

 philia is the property which both classes may have in common, although 

 it is more marked in one of them. Chromatin and eleidin are chromo- 

 philous, and both have a preference for basic dyes. 



* Amer. Mori. Micr. Journ., viii. (1887) pp. 153-5. 



t Med. Centralbl., 1886, No. 51, pp. 931-2, and No. 52, pp. 945-7. 



X See this Journal, 1887, p. 1058. 



