IN VEBTEBRA TES 6 1 1 



1212. Echinoidea. Lee advises that they be killed by injection 

 of some fixing liquid. For preservation, formaldehyde has proved 

 admirable in all respects, and greatly superior to alcohol 

 (Weber). 



Lo Bianco kills by pouring over them (mouth upwards) a 

 mixture of 10 parts acetic acid and 1 of 1 per cent, chromic acid, 

 and brings at once into weak alcohol. Or he makes two holes in 

 the shell, lets the water run out and alcohol in. 



Sections of spines may be made by grinding, see §§ 202, 910. 



Spicula and the skeleton of pedicellariai may be cleaned by 

 eau de Jarvelle, see Doderlein {Wiss. Ergeb. Tiefsee-Exped., v, 

 1906, p. 67). 



1213. Asteroidea. Hamann (Beiir. Hist. Echinodermen, ii, 

 1885, p. 2) injects the living animal with a fixing liquid through 

 the tip of a ray. The ambulacral feet and the branchiae are soon 

 distended by the fluid, and the animal is then thrown into a 

 quantity of the same reagent. 



In order to study the eyes, with the pigment preserved in situ, 

 they should be removed by dissection, should be hardened in a 

 mixture of equal parts of 1 per cent, osmic acid and 1 per cent, 

 acetic acid, and sectioned in a glycerin gum mass, or some other 

 mass that does not necessitate treatment with alcohol (which 

 dissolves out the pigment, leaving the pigmented cells perfectly 

 hyaline). For maceration use one-third alcohol, the aceto-osmic 

 mixture failing to preserve the rods of the pigmented cells. 



Specimens for externals only preserve in 70 per cent, alcohol 

 or formalin. They retain their shape better if they are put for 

 two or three minutes into fresh water before being placed in the 

 fixer. If the internal anatomy is to be studied, cut along the 

 length of each arm so as to allow fluid to enter, and preserve in 

 2 per cent, chromic acid, etc. Wash in running water, transfer to 

 70 per cent, alcohol ; or the specimen may be preserved in formalin 

 spirit or 5 per cent, formalin. 



Formaldehyde is not to be recommended for the cell preservation 

 of Asteroidea (Weber). See also Lo Bianco, op. cit. (he kills 

 Brisinga with absolute alcohol), also §§ 14 et seq. 



1214. Ophiuridea should in general be killed in fresh water if 

 it be desired to avoid rupture of the rays (De Castellarnau, 

 La Est. Zool. du Napoles, p. 135). 



Lo Bianco kills small forms with weak alcohol, Ophiopsila with 

 absolute alcohol, and Ophiomijxa with 0-5 per cent, chromic acid. 



Russo {Richerche Lab. Anat. Roma, iv, 1895, p. 157) fixes 

 Ophiothrix for an hour or two in 0-5 per cent, osmic acid and 

 then decalcifies in solution of Miiller for six to ten days. Or he 

 fixes for three minutes in a mixture of 2 parts concentrated 

 sublimate solution, 1 part 70 per cent, alcohol, and 1 part acetic 

 acid (sp. gr. 1-06), and decalcifies in Miiller or in 70 per cent. 



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