12 KILLING. 



a mixture (invented by SALVATORE LO BIANCO) containing 20 

 parts of glycerin, 40 parts of 70 per cent, alcohol, and 40 parts 

 of sea- water. This mixture should be carefully poured on to 

 the surface of the water containing the animals, and allowed 

 to diffuse quietly through it. Several hours are sometimes 

 necessary for this. 



EISIG employs alcohol in the same way. 



13. Methyl-alcohol. COEI (Zelt. f. wiss. Mik., vi, 4, 1890, 

 p. 438) prefers methyl-alcohol to all other reagents. It has, 

 amongst other advantages, that of having but a slight action 

 on albumins. CORI recommends a mixture composed of 10 c.c. 

 methyl-alcohol (of 96 per cent, strength), 90 c.c. water (fresh 

 or sea-water), and 0'6 g. of sodium chloride (to be added only 

 when fresh water is taken, the addition of the salt having for 

 its object to prevent maceration). 



14. Hydrate of Chloral, which was first recommended, I 

 belive, by Foettinger (Arch, de Biol., vi, 1885, p. 115), gives 

 very good results with some subjects. Foettinger operates 

 by dropping crystals of chloral into the water containing 

 the animals. For Alcyonella he takes 25 to 80 centigrammes 

 of chloral for each hundred grammes of water. It takes 

 about three quarters of an hour to render a colony suffi- 

 ciently insensible to allow of fixing. Foettinger has obtained 

 satisfactory results with marine and fresh-water Bryozoa, 

 with Annelida, Mollusca, Nemertians, Actiniae, and with 

 Asteracanthion. He did not succeed with Hydroids. 



I am bound to state that I have never had the slightest success with Ne- 

 mertians. 



VEBWORN (Zeit.f. wiss. Zool., xlvi, 9, 1887, p. 99; see also Journ. Roy 

 Mic. Soc., 1888, p. 148) operates differently for fresh-water Bryozoa. He 

 puts Cristatella for a few minutes into 10 per cent, solution of chloral, in 

 which the animals sooner or later become extended. 



KUKENTHAL (Zeit.f. wiss. Mik., iv, 8, 1887, p. 878 ; Journ. Roy. Mic. 

 Soc., 1888, p. 509) has obtained good results with some Annelids, by means 

 of a solution of one part of chloral in 1000 parts of sea-water. 



The chloral method gives rise to maceration with some 

 subjects, and has been found to distort nuclear figures. 

 (This, I suspect, will probably be found to be the case with 

 most of these methods.) 



