PROTOZOA 575 



delicacy, it is unlikely that they could be kept alive even were the 

 solution used more dilute. 



Ink (Stephens' blue-black) is excellent for staining the epispores 

 of grcgarine and other spores to show up their processes (Quart. 

 Journ. Micr. Sci., 61, 1915, p. 83). A half-saturated solution of 

 methyl blue in distilled water is also very good for the same 

 purpose and less likely to cause a precipitate when host tissue or 

 fluids are present. 



Certes {Bull. Soc. Zool. de France, xiii, 1888, p. 230) recom- 

 mends examination of organisms in coloured media, in which 

 they do not stain but show up on a coloured background, saying 

 that infusoria will live in a solution of anilin black for weeks. 

 Fabre-Domergue {A?in. de Microgr., ii, 1889, p. 545) uses in 

 this way a concentrated solution of diphenylamin blue. 



For preparing coverslips for neutral red staining see under 

 Blood, § 872. For a general discussion of the whole subject 

 refer to Chapter XXXI, §§ 739 to 775. 



1124. Demonstration of Cilia and Flagella. Any of the above 

 inethods which slow down the rate of movement of the ciliates 

 and flagellates will tend to show up the cilia or flagella by which 

 they move (see also the effect of iodine below). 



Tannin (tannic acid), the solution recommended by Wadding- 

 ton {Journ. Roy. Micr. Sac, 1883, p. 185) for demonstrating cilia 

 of Paramoecium, has, in my hands, exactly the same effect as, 

 judging by his figures, it had in his, viz. the extrusion of tricho- 

 cysts. With very dilute solutions some trichocysts are shot out, 

 and often they are so thick that the cilia are hidden altogether. 



Sulphurous acid. An alcoholic solution was recommended by 

 Waddington (see above) for showing up cilia. It is useful also 

 for reducing the activity of ciliates. I cannot find, however, that 

 an alcoholic solution is any better than an aqueous one, e.g., 

 equal volumes of normal sodium bisulphite and hydrochloric acid 

 solutions coloured with neutral red. 



1125. Toxic Mounting Media. Useful observations may often 

 be made on protozoa by adding to them gradually (by running 

 in under the coverslip) or mounting them direct in certain toxic 

 media. 



Iodine is especially serviceable in this way. It is used in 

 watery solution {i.e. dissolved in a solution of potassium iodide) 

 of a light sherry colour. Lugol's solution is a suitable strength. 

 Cilia and flagella generally show up very clearly, being temporarily 

 fixed by the iodine. Any starch present is, of course, stained 

 blue, and glycogen brownish ; the latter being somewhat soluble 

 in water, will generally show a blurred edge. 



For the examination of faeces for protozoa and their cysts, it is 

 a great help to have preparations mounted in iodine solution as 

 well as in normal saline. Routine examination for diagnostic 



