528 



SUM3IARY OF CURRENT RESEARCHES RELATING TO 



chamber the white bloocl-cori^uscles of the frog, tinged with cyanin, 

 presented amceboid movements; serum was found to dissolve the 

 cyanin better than water. 



The coloration appears to be concentrated around the fat-granules 

 of the protoplasm ; it is feeble, not to say nil, in the cilia, the cuticle, 

 and the vacuoles ; the nucleus and nucleolus escape completely ; this 

 is so far an advantage that it makes the observation of the division of 

 the se bodies more easy, and affords a demonstration of the difference in 

 chemical composition between them and the surrounding protoplasm. 

 The whole series of observations are interesting as demonstrating 

 that it is not impossible to colour a living cell. 



Double and Treble Staining-.* — The process of using dyes of 

 two ditierent colours, so as to differentiate more clearly certain parts 

 of a microscopic section of an organ, is, Dr. W. Stirling considers, of 

 the greatest value, and can be employed with excellent results even 

 by students. Having used various methods for the last three years, 

 he now gives a brief account of those combinations of colours which 

 he has found to be most useful for class purposes, and the organs for 

 which each combination is best suited. 



(1) Osmic Acid and Picrocarmine — Blood of a Newt or Frog. — 

 Mix a drop of blood with a drop of a 1 per cent, aqueous solution of 

 osmic acid, and allow the slide to stand. This " fixes '' the corpuscles 

 without altering their shape. At the end of five minutes remove the 

 excess of osmic acid with blotting-paper, add a drop of solution of 

 picrocarmine and a trace of glycerine to prevent evaporation, and set 

 aside for three or four hours (or even longer, as no overstaiuing takes 

 place). At the end of this time the nucleus will be found to be 

 stained red, and the perinuclear part homogeneous and yellow. 



(2) Picric Acid and Picrocarmine — Blood of a Newt or Frog. — 

 Place a drop of blood on a slide, and add a drop of a saturated solu- 

 tion of picric acid ; put the slide aside and allow it to remain for five 

 minutes, and at the end of that time, when the acid has " fixed " the 

 corpuscles (that is, has coagulated their contents), the excess of acid 

 should be removed by means of a narrow slip of blotting-paper. A 

 drop of a solution of picrocarmine should now be added, and a trace 

 of glycerine to prevent evaporation, and the prej^aration set aside for 

 an hour. At the end of that time remove the picrocarmine solution 

 by means of a slip of blotting-paper, and add a drop of Farrant's 

 solution or glycerine, and apply a cover. The preparation may then 

 be examined, when the perinuclear part of some of the corpuscles will 

 be seen to be highly granular and of a deej^ yellow colour, while the 

 nucleus is stained red. In some of the corpuscles there may also be 

 seen delicate yellow-coloured threads, extending from the nucleus to 

 the envelopes ; in others, the perinuclear part remains uniformly 

 homogeneous. This and the above preparation of blood-corpuscles 

 can be preserved in glycerine. 



The processes for Yellow Elastic Tissue, Yellow Fibro-Cartilage, 

 Fcetfd Bone, and the Aorta are also described. 



* Jouru. Anat. an.l Physiol., xv. (1881) pp. P.49-54. 



