524 METHODS FOE INVERTEBRATES. 



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. 



987. BIGELOW (Mem. Boston 8oc. nat. 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. 



988. Medusae : Sections. Paraffin and collodion are certainly not 

 satisfactory as all-round methods for these watery organisms. The 

 HERTWIGS (Nervensystem der Medusen, 1878, p. 5) embedded 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 

 in Chapter VIII. 



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

 nervous system, 526. Doubtless in many cases the pyrogallic acid 

 reaction, 374, would give enhanced differentiation. 



990. Siphonophora. For the cupric sulphate method of BEDOT 

 (Arch. Sci. phys. et nat., xxi, 1889, p. 556), which is admirable for the 

 preparation of museum specimens, but not necessary for histological 

 work, as well as for those of Lo BIANCO (op. cit., p. 454), FRIED- 

 LANDER (Biol. CentrbL, x, 1890, p. 483), and DAVIDOFF (Anat. Anz., 

 xi, 1896, p. 505) see previous editions. Lo BIANCO fixes most forms 

 with the mixture given in 8 1021. 



^j o 



For preserving, according to WEBER, formaldehyde is better than 

 alcohol. DAVIDOFF (loc. cit.) fixes in it. 



991. Ctenophora : Fixation. Never store in formalin, always in 70 

 per cent, alcohol. Pleurobrachia are best killed in 5 per cent, formalin 

 in sea water. Fill large measuring jar with this fluid, drop in the 

 animals and leave till they sink to the bottom ; transfer to 5 per cent, 

 formalin in pure water. After a week or so (not longer) transfer to 

 very dilute alcohol, and up-grade to 70 per cent, strength. Beroe : 

 Bring into small quantity of sea water, and when expanded add large 

 quantity of corrosive sublimate saturated solution in sea water. 

 When specimens become white, decant and add fresh water ; wash 

 in several changes to remove corrosive, up-grade to 70 per cent, 

 alcohol. Bolina dissolves at once in formalin ; kill in Flemming, 

 selecting small specimens : leave half an hour, wash slightly, 

 up-grade to 70 per cent, alcohol. (ALLEN and BROWNE in Science 

 of the Sea. London. John Murray. 1912.) 



