16 HIALTKU II. 



few minutes into 10 per cent, solution of chloral, in which the animals 

 sooner or later become extended. 



KUKENTHAL (Jena Zt'it. Nttturiv., Bd. xx, 1887, p. 511; has obtained 

 good results with some Annelids by means of a solution of one part of 

 chloral in IGOO parts of sea water. 



The chloral method gives rises to maceration with sonic 1 

 subjects, as I can testify, and has been said to distort nuclear 

 figures. 



21. Cocaine (RICHARDS, Zoul. Anz., 196, 1885, p. 332).- 

 Richards puts a colony of Bryozoa into a watch-glass with 5 

 c.c. of water, and adds gradually 1 per cent, solution of 

 hydrochlorate of cocaine in water. After five minutes the 

 animals are somewhat numbed, and half a cubic centimetre 

 of the solution is added; and ten minutes later the animals 

 should be found to be dead in a state of extension. 



This method is stated to succeed with Bryozoa, Hydra, and 

 certain worms. It is the best method for Rotifers (ROUSSELET). 

 It has also been recommended for Aplysia. 



It has been pointed out (by Com, in the paper quoted 18) that, 

 unfortunately, when fixing agents, such as sublimate solution, are 

 added to the animals, the cocaine is thrown down, on them as a white 

 precipitate. This precipitate, however, may be redissolved afterwards 

 in alcohol (Eisio). 



Cocaine solutions cannot be depended 011 to keep for more than a few 

 days. 



22. Eucain. HARRIS (Journ. Roy. Hie. Soc., 1900, p. 404) 

 recommends a 1 per cent, solution of eucain hydrocliloride, as 

 giving far better results, with Vorticellida3, Rotatoria, and 

 Vermes. ROUSSELET (ibid.) reports favourably as to its action 

 on Flosculariae. It is stated to be perfectly stable in aqueous 

 media. It dissolves in sea water to about 0'5 per cent. 



23. Hydroxylamin. HOPER (Zeit. wis*. Mil;., vii, 18110, p. 318). 

 Either the sulphate or, preferably, the hydrochlorate may be used. 

 This should be dissolved in water (spring or sea water, according to the 

 habitat) and exactly neutralised by addition of carbonate of soda. The 

 organisms are placed in a solution diluted to about O'l per cent., for 

 thirty minutes or less (as for Infusoria), to 0'25 per cent., for from 

 fifteen minutes to one hour (Hydra), 1 per cent., one half to two hours 

 (Hirudo), or as much as ten to twenty hours (Helix im<lAnodo)ila). 



Hydroxylamin is a powerful reducing agent, and should therefore be 

 well washed out before treating with easily reducible fixing agents. 



