482 CHAPTER XXXIV. 



ration use one third alcohol, the aceto-osmic mixture failing 

 to preserve the rods of the pigmented cells. 



Formaldehyde is not to be recommended for the preser- 

 vation of Asteroidea (WEBER). 



See also Lo BIANCO, loc. cit., p. 458 (he kills Brisinga 

 with absolute alcohol) ; also 15, 18. 



862. Ophiuridea should in general be killed in fresh 

 water if it be desired to avoid rupture of the rays (DE 

 CASTELLARNAD, La Est. Zool. de Napoles, p. 135). 



Lo BIANCO (loc. cit., p. 458) kills small forms with weak 

 alcohol, Ophiopsila with absolute alcohol, and Oplnomyxa 

 with 0'5 per cent, chromic acid. 



Russo (Ricerche 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 two parts 

 concentrated sublimate solution, one part 70 per cent, 

 alcohol, and one part acetic acid (sp. gr. l'06j, and decal- 

 cifies in Miiller or in 70 per cent, alcohol with 10 per cent, 

 of acetic acid. He stains with paracarmine. 



863. Echinoidea. I advise 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 (loc. cit., p. 458) kills by pouring over them 

 (mouth upwards) a mixture of ten parts acetic acid and one 

 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 run in. 



Sections of spines may be made by grinding, see 176. 



864. Crinoidea. Lo BIANCO (loc. cit., p. 458) fixes Antedon 

 rosacea with 70 per cent, alcohol, A. phalangium with 90 

 per cent. 



865. Larvae of Echinodermata (from instructions written 

 down for me by Dr. BARROIS). In order to a fruitful study 

 of the metamorphoses of the Echinoidea and Ophiuridea it 

 is necessary to obtain preparations that give distinct images 



