MKTHODS FOR INVEltTEJJIiATKS. 463 



KAISER (Biblinth. Zool., H. vii, 1 Halffce, 1891, p. 3) found 

 that a saturated aqueous solution of cyanide of mercury, 

 warmed to 45 to 50 C., and allowed to act for from fifteen 

 to sixty minutes, and then washed out with 70 per cent, 

 alcohol, was the best of all fixing media. 



888. Nematodes. The impermeable cuticle is a great obstacle 

 to preparation. According to Looss (Zool. Auz. } 1835, p. 

 318) this difficulty may be overcome in the manner described 

 in 553. 



For fixing, most recent authors recommend sublimate 

 solutions ; chromic solutions seem to have a tendency to 

 make the worms brittle. 



But, according to ZUR STRASSEN (Zeit. wiss. Zool., liv, 

 p. 655), Brady nema rigidum ought to be fixed for at least 

 twelve hours in mixture of Flemming. 



AUGSTEIN (Arch. Naturg., Ix, 1894, p. 255) takes for 

 Stroiigyins Jilaria Mayer's picro-nitric acid. 



VEJDOVSKY (Zeit. wins. Zool., Ivii, 1894, p. 645) advises for 

 Gordius O5 per cent, chromic acid (twenty-four hours). 



Lo BIANCO employs for marine forms concentrated subli- 

 mate or picro -sulphuric acid. 



Looss (Zool. AHZ., xxiv, 1901, p. 309) prefers hot (80 to 

 90 C.) alcohol of 70 per cent. 



GrLAUE (Zeit. iviss. Zool., xcv, 1910, p. 554) kills Ascaris 

 in a hot mixture of 100 parts of saturated sublimate, 100 of 

 alcohol, and 1 of acetic acid. 



Staining is frequently difficult, and sometimes alcoholic 

 carmine, 234A, is the only thing that will give fair results. 



BRAUN (see Jotirn. Roy. Mic. Soc., 1885, p. 897) recommends that 

 small unstained Nematodes be mounted in a mixture of 20 parts gelatin, 

 100 parts glycerin, 120 parts water, and 2 parts carbolic acid, which is 

 melted at the moment of using. Canada balsam, curiously enough is 

 said to sometimes make Nematodes opaque. 



Demonstration of living Trichinx. BARNES (Amer. Mon. milt. Journ., 

 xiv, 1893, p. 104) digests trichinised muscle (of the size of a pea) in a 

 mixture of 3 gr. of pepsin, 2 dr. of water, and 2 minims of hydrochloric 

 acid, kept at body temperature for about three hours. The flesh and 

 cysts being dissolved, the fluid is poured into a conical glass, and 

 allowed to settle ; the trichinae are drawn off from the bottom with a 

 pipette, got on to a slide with water and examined on a hot stage. 



GRAHAM (Arch. mile. Anat., 1, 1897, p. 216) isolates Trichinae by 



