ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 393 



Tbe author, after describing various forms of incubators suitable for 

 amoeba? cultures, addresses himself to staining procedures. The first of 

 these is that of Romanowsky and Nocht. A few drops of 1 per cent, 

 alcoholic solution of eosin are mixed with 2 ccm. of water, and this 

 mixed with a solution of 1 per cent, methylen-blue in ^ per cent, soda 

 solution. The latter is dropped in until the colour is a dark-brown 

 violet. The fixed films are floated on this mixture for about ten minutes, 

 and then, having been washed in water, are treated in the usual manner. 



Lowit treats his specimens of leukhaemic blood as follows : — The 

 films are dried for 1-lh hour at 110°-115°, and are then stained in 

 a mixture of 30 parts alkaline methylen-blue (Loeffler) and 15 parts 

 of saturated aqueous solution of thionin. The preparations are stained 

 for 15-20 minutes, washed in water, and differentiated in acid alcohol 

 (0"3 per cent. HC1.) as long as the stain is given off. They are then 

 treated in the usual way. The kaematozoa are blue to green. 



Another method is to stain the fixed film in saturated aqueous solu- 

 tion of thionin for half an hour, and, after washing and drying, immerse 

 for 10-20 seconds in iodopotassic iodide solution ; wash again and 

 mount in balsam. The parasites are green. 



A similar stain had been previously recommended by Mallory for 

 Amoeba coli. The film was fixed in alcohol, stained in saturated aqueous 

 solution of thionin for 5-20 minutes, washed, differentiated in 2 per 

 cent, oxalic acid solution for ^-1 minute, dehydrated in 55 per cent, 

 alcohol, and mounted. 



For demonstrating the malaria parasite, Korosko's mature solution 

 of methylen-blue and eosin is mentioned. This consists of methylen- 

 blue C or B. G. N. 1 ; distilled water 100 ; absolute alcohol 5 ; 20 per 

 cent, caustic potash 12 drops. After standing for three months, 2 ccm. 

 of the filtered solution are mixed with 4 ccm. of 1 per cent, eosin solu- 

 tion. The films are fixed for one hour at 105°-110°, and then stained in 

 the foregoing mixture for 12-21 hours at 30°. 



(2) Preparing- Objects. 



Value and Action of Fixative Fluids.* — Dr. W. von Wasielewski, 

 after an exhaustive examination of the respective values of fixative 

 solutions, lays it down that on the whole the best results are obtained 

 from Flemming's fluid and its modifications, such as Hermann's and 

 vom Eath's mixture. With these may be included other fluids which 

 contain acetic acid, such as Zenker's, Carnoy's, Telyesniczky's, and also 

 picroacetic acid, chromacetic and sublimate acetic acid, and some others. 



With the exception of platinum chloride, fixative solutions containing 

 only one ingredient are of less value than mixtures. . The special pro- 

 perties of the chief media may be appreciated thus. Osmic acid and 

 potassium bichromate are the best for retaining the cell-mass. Platinum 

 chloride, as a simple fixative, does well for nuclear division, and the 

 staining with safranin-gentian-violet-orange is excellent. Acetic acid 

 holds the first position for its structure-retaining properties. Picric acid 

 penetrates most rapidly. 



Centrosomes are not demonstrable by any fixing or staining method. 



* Zeitschr. f. wisa. Mikr., xvi. (l'JOO) pp. 303-4S ('2 pi.). 



