518 METHODS FOR INVERTEBRATES. 



osmic acid is not good, and liquid of Miiller macerates. He stains 

 with borax-carmine, makes sections, and puts them for ten minutes 

 into osmic acid, then for five minutes into pyroligneous acid, on the 

 top of the stove. He macerates the visual rods in a mixture of 

 1 part common salt, 1 of acetic acid, and 100 of water. He bleaches 

 the pigment of the eyes with peroxide of hydrogen. 



WILHELMI (ibid., Ixxx, 1906, p. 548) throws Triclads into almost 

 boiling mixture of Zenker, and after ten to thirty minutes removes 

 to water for some hours, and then passes into iodine alcohol. 



Echinodermata . 



970. Holothurioidea.- -These are difficult to fix on account of 

 their contracting with such violence under the influence of irritating 

 reagents as to expel their viscera through the oral or cloacal 

 aperture. 



VOGT and YUNG (Anat. Comp. Prat., p. 641) say that Cucuniaria 

 Planci (C. doliolum, Marenzeller) is free from this vice ; but they 

 recommend that it be killed with fresh water, or by slow intoxication, 

 25. 



Synapta may be allowed to die in a mixture of equal parts of 

 sea water and ether or chloroform (S. Lo BIANCO). 



OESTERGREN ( 18) puts Synapta into his ether water, but Dendro- 

 chirota first into magnesium sulphate of 1 to 2 per cent., for some 

 hours. 



GEROULD (Bull. Mus. Harvard Coll., xxix, 1896, p. 125) paralyses 

 Caudina with sulphate of magnesia, 24, and fixes with liquid of 

 Perenyi (or sublimate for the ovaries). 



Holothurids, Dr. WEBER informs nie, are admirably preserved 

 in formaldehyde ; a weak solution is sufficient. 



For the staining of muscles with methylen blue, see IWANZOFF, 

 Arch. mile. Anat., xlix, 1897, p. 103 ; and for the study of calcareous 

 plates, see WOODLAND, Quart. Journ. Micr. Sci., xlix, 1906, p. 534 

 (fixation with osmic acid, staining with picro -carmine, followed by 

 Lichtgriin). 



971. 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 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 run in. 



Sections of spines may be made by grinding, see 177. 



