IN VERTEBRA TES 6 1 7 



admirable for the {)reparation of musciun specimens, but not 

 necessary for histological work, as well as for those of Lo Bianco 

 (op. cit., p, 454), Friedlander {Biol. Centrbl., x, 1890, p. 483), 

 and Davidoff [Anat. Anz., xi, 1896, p. 505) see previous 

 editions. Lo Bianco fixes most forms with sublimate in sea- 

 water. 



For preserving, according to Weber, formaldehyde is better 

 than alcohol. Davidoff {loc. cit.) fixes in it. 



1229. 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 upgrade to 

 70 per cent, strength. Beroe : Bring into small quantity of sea- 

 water, and when expanded add large quantity of corrosive sub- 

 limate saturated solution in sea-water. When specimens become 

 white, decant, and add fresh water ; wash in several changes to 

 remove corrosive, u})grade to 70 per cent, alcohol. Bolina 

 dissolves at once in formalin ; kill in Flemming, selecting small 

 specimens ; leave half an hour, wash slightly, upgrade to 70 

 per cent, alcohol. (Allen and Browne in Science of the Sea. 

 London. John Murray. 1912.) 



Small forms are very easily prepared by means of osmic acid. 

 For the large forms see Lo Bianco, loc. cit., p. 457. He uses his 

 copper sulphate mixture, § 1227. 



Samassa makes sections by the double-imbedding method. 

 See Arch. }nik. Anat., xl, 1892, p. 157. 



1230. Plankton, Preservation of, without Sorting (E. J. Allen 

 and E. T. Browne in Science of the Sea. John Murray. 1912). 

 Preservation of whole catch of a tow-net is performed by stirring 

 around the Plankton with a rod and adding a little 5 to 10 per 

 cent, formalin. Keep on stirring for about a minute, then allow 

 the organisms to settle to the bottom ; as soon as this occurs 

 pour off as much of the liquid as possible and transfer the Plankton 

 to a bottle ; again allow to settle and reduce the fluid to a minimum 

 then fill the bottle with 5 or 10 per cent, formalin. A bottle 

 should be not more than half full of Plankton. After a few days, 

 or on the appearance of opalescence of the fluid, change the 

 liquid. Another method is first to fill the Plankton by pouring 

 some saturated solution of picric acid into the jar containing the 

 organisms, then add some formalin 5 or 10 per cent, and leave 

 for an hour or two, occasionally stirring. Finally decant and 

 add 5 or 10 per cent, formalin as before described ; the yellow 

 colour of the fluid can be neglected. Never use corrosive sub- 

 limate with formalin, as crystals form, which adhere to the 

 organisms. 



