ZOOLOGY AND BOTANY, MICROSCOPY, ETC, 653 



alcoholic safrauin solution for half au houi* ; they should be washed 

 slightly in water, and then dehydrated as quickly as possible by 

 absolute alcohol, then transferred to turpentine and mounted in 

 balsam. Some tissues which are not so readily decolorized may be 

 clarified with oil of cloves. Although they api^ear scarcely red, yet 

 such sections show the following structures : viz. nucleoli of white 

 blood-corpuscles ; granules in the same and in most cells of rapidly 

 proliferating granulating tissues ; periphery of red blood-corpuscles ; 

 filamentous bodies occurring in connection with blood-vessels in 

 process of formation ; nuclei of giant-cells and nucleoli of all large- 

 celled sarcomata and carcinomatous tumours. 



As the inactive, skeletal part of the nucleus is not stained by the 

 safranin, it is easy to follow by its means the part which the nucleolus 

 plays in cell-division. In large-celled, malignant tumours a great 

 variety of forms are thus brought out in the nucleus, while the 

 spindles and the fibrils connecting them remain uncoloured. In 

 melanosarcoma the fission-stages of the cells, which remain concealed 

 under every other treatment, are well brought out, and in rapidly 

 growing small-celled tumours, e. g. lymphosarcomata, the appearance 

 of universal staining is imparted to the cell by a series of delicate 

 nuclear markings which almost fill the cell. 



Secondly, for investigating the structure of the cell and of other 

 histological elements a super-saturated solution should be employed ; 

 it is warmed to 60°, and filtered in this state ; the sections are placed 

 in a small quantity of the liquid in a watch-glass, which is then 

 warmed * for a few seconds over a spirit-lamp until the precipitating 

 crystals are redissolved; the sections are left for a minute, then 

 washed in water, and treated as in the former case. Tissues which 

 do not stain readily should be warmed again and again. The nuclear 

 network comes out well under this treatment. It is especially 

 adapted for delicate structures and for bacteria ; every micrococcus 

 appears brownish-red, while the surrounding tissues assume a fine 

 rose-red ; the bacilli of tuberculosis and lepra are not thus stained. 



Thirdly, the sections may be left for 12 to 24 hours in the solu- 

 tion (either concentrated watery or alcoholic, or a mixture of the two). 

 Sections thus coloured may be left, if necessary, somewhat longer in 

 alcohol, turpentine, oil of cloves, or, better, origanum ; a large number 

 of details are thus brought out, and a similar effect is produced by 

 longer action of a watery solution ; the method is especially adapted 

 to tumours of the brain or spinal cord. 



The finest representations of the changes undergone by nuclei in 

 fission were produced by rapidly staining with safranin, followed by 

 eosin, and mounting in balsam. Safranin and hajmatoxylin bring 

 out the nuclear skeleton violet and the nucleolus red. Preparations 

 made according to these methods have proved durable. Some points 

 are better seen by mounting in glycerin, but the colour disappears 

 more or less in time, and acetate of potash is preferable both on the 

 grounds of permanency and clearness. 



* Cf. tliia Journal, iii. (1883) p. 918. 



