778 SUMMARY OF CURRENT RESEARCHES RELATING TO 



potassium carbonate ' 5, water 50 ; (2) cyanide of potassium 1, water 50 ; 

 (3) potassium iodide 1 p.c. Mix equal parts before staining. 



Alizarin, a Vital and Specific Stain for Nervous Tissue.* — H. 

 Fischel has found in alizarin a pigment which will stain intra-vitam the 

 nerves of Cladocera. The simplest method is to drop some of the powder 

 into the water in which the animals live, and in a few hours to a few 

 days the nervous system of some of the animals will be found stained a 

 dark violet. Better results are obtainable by means of a solution of 

 alizarin made by dropping the powder into boiling water and continuing 

 the boiling for some time. The clear filtrate is used and an equal quan- 

 tity added to the water in which the animals are. When successful the 

 staining results are said to be excellent. The method, however, has certain 

 disadvantages : — (1) the action of the stain is somewhat uncertain, thus 

 under similar conditions some animals will be found well stained, others 

 not at all ; (2) the stain seems to be specific for Cladocera only, other 

 animals ha vino- failed to be affected bv its action. 



*)7> 



Vital Staining of Fresh-water Animals. — The same author gives 

 an interesting account of the results of his researches on the vital 

 staining of fresh-water animals, with especial reference to Cladocera. 

 The dyes were used in extremely dilute solution. The principal pig- 

 ments used were neutral-red, neutral-violet, Nile-blue, Bismarck-brown, 

 methylen-blue, and toluidiu-blue. Combinations of these stains were 

 also used. Coloured illustrations show the effect of the pigments, and 

 special attention may be drawn to the action of alizarin on the nervous 

 svstem. The author also alludes to the influence of light. He found 

 that rays of long wave-length intensified the action of the stain, and 

 quotes the result of lithium-carmin in combination with ruby glass as a 

 light-filter. In the last section he discusses the theory of vital staining. 



Flemming's Triple Staining Method.! — H. V.Winiwarter and 

 Gr. Sainmont allude to the unfavourable criticisms of this method, and 

 then state that unsatisfactory results are due to the insufficient directions 

 given in the original. They have adopted the procedure for twelve 

 years, and have found that, with the following slight modifications, it 

 gives excellent results. 



Though the triple staining is specially adapted for material fixed 

 with Flemming's solution, it may be used after other fixatives provided 

 that the sections are immersed in Flemming's solution for 24 hours, and 

 afterwards washed for about 20 minutes in running water. 



After fixation for 24 hours in Flemming's solution, it is indispensable 

 that the pieces should be thoroughly washed in running water for 

 24 hours. After this they may be passed through up-graded alcohols to 

 paraffin. The paraffin should be removed by means of xylol unaided 

 by heat. The sections are next treated with a mixture of xylol and 

 absolute alcohol, then twice with absolute alcohol, followed by 95 p.c. 

 and 65 p.c. alcohols. The slides are placed for 24 hours in safranin 



* Zeitschr. wiss. Mikrosk., xxv. (1908) pp. 154-7. 



t Internat. Revue ges. Hydrobiol. u. Hydrograph., i. (1908) pp. 73-141 (2 pis.). 



% Zeitschr. wiss. Mikrosk., xxv. (1908) pp. 157-62. 



