238 CHAPTER XIX. 



Another method is as follows : Serum is mixed with a 

 large proportion of tincture of iodine ; the precipitate that 

 forms is removed by filtration, and there remains a strong 

 solution of iodine in serum. This should be kept in stock, 

 and a little of it added every two or three days to the 

 serum that is intended for use. In general for maceration 

 purposes a serum of a pale brown colour should be em- 

 ployed. 



406. Artificial Iodised Serum (FKEY, Das Mikroscop, 6 Aufl., 

 1877, p. 75). Distilled water 270 grins., white of egg 30, 

 sodium chloride 2*5. Mix, filter, and add tincture of iodine. 



407. MIGULA'S Glycerized Blood-serum (see the paper hi Zeit. f. 

 wiss. Mile., vii, 2, 1890, p. 172). 



408. Chloride of Calcium (HARTING, Das Mikro.<kop, 2 Aufl., p. 297). 

 The aqueous solution, either saturated or diluted with 4 to 8 parts of 



water, has a low refractive index and does not dry up. 



409. Acetate of Potash (MAX SCHULTZE, Arch. mik. Ancd., vii, 1872, 

 p. 180). A nearly saturated solution in water. The index of refraction 

 is lower than that of glycerin. 



410. Syrup. A good strength is equal parts of loaf sugar 

 and water. Dissolve by boiling. To preserve it from 

 mould, chloral hydrate may be dissolved in it (1 to 5 per 

 cent.) I have used as much as 7 per cent., and found no 

 disadvantage or carbolic acid (1 per cent.). 



It may be used as a mounting medium, but there is always 

 risk of the sugar crystallising out. 



FABRE-DOMERGUE (Bull. Soc. Philomath, ix, 1899, p. 115) 

 dissolves 200 parts of suger in 400 of water, and adds 1 

 part of formaldehyde, and camphor to saturation. 



411. Chloral Hydrate. 5 per cent, in water (LADOWSKY, 

 Arch. f. mik. Ancd., 1876, p. 359). 



Or, 2'5 per cent, in water (BEADY, British Copepods). 

 Or, 1 per cent, in water (MUNSON, Joimi. Roy. Mic. Soc., 

 1881, p. 817). 



