616 INVERTEBRATES 



cent, solution. Place the medusae in a small glass vessel with 

 just enough sea-water to allow them to swim. After they have 

 expanded add a little cocaine (3 c.c. of 1 per cent, solution for 

 every 100 c.c. of sea-water). If the medusae at the end of ten to 

 fifteen minutes do not contract when touched with a glass-rod 

 no more cocaine is needed ; if they are still active add more 

 narcotiser and stir ; an overdose will cause prolonged contraction. 

 After anaesthetising add the formalin and keep stirring, and 

 continue for a minute, or longer. Do not leave specimens in 

 solutions of cocaine longer than necessary. (Allen and Browne 

 \n Science of the Sea. London. John Murray. 1912.) 



For further description of narcoiisation methods see §§ 16 

 et seq. 



For killing by heat see § 11. 



Fixation. In general polyps may be very well killed in saturated 

 sublimate solution, in which they should be plunged for an instant 

 merely, and be brought into alcohol. The solution should be 

 employed cold in general for Gymnoblastea, hot for most Calypto- 

 blastea. 



Ether attentively administered gives good results with 

 Campanularidae. Hydra is very easily killed by a drop of osmic 

 acid on a slide. 



For the methylen blue intra-vitam method, see Chapter XVIII. ; 

 also Hadzi, Arb. Zool. Inst. Wien, xvii, 1909, p. 225. 



1227. Medusae : Fixation. For narcotisation see § 16 and 

 above. 



Trachymedusae and Acalephae may be fixed in the usual way 

 in chromic or osmic mixtures. Osmic acid may be added to the 

 sea-water containing the animals, which should be removed to 

 spring water as soon as they begin to turn brown. 



BiGELOw {Mem. Boston Soc. not. Hist., v, 1900, p. 193) fixes the 

 scyphistomes of Cassiopeia in Lo Bianco's mixture of 10 parts of 10 

 per cent, solution of cupric sulphate with 1 of saturated sublimate, and 

 hardens them in 5 per cent, bichromate of potash. 



Medusae : Sections. Paraffin and collodion are certainly not 

 satisfactory as all-round methods for these watery organisms. 

 The Hertwigs {Newensystem der Medusen, 1878, p. 5) imbedded 

 in liver with the aid of glycerin gum, and hardened the objects 

 and the mass in alcohol. 



See also Joliet's glycerin gum method, and the gelatin methods 

 on page 97. 



Medusae : Maceration. See, especially for the study of the 

 nervous system, § 568. Doubtless in many cases the pyrogallic 

 acid rcactioji, § 413, would give enhanced differentiation. 



1228. Siphonophora. For the cupric sulphate method of 

 Bedot (Arch. Sci. phys. et not., xxi, 1889, p. 556), which is 



