480 CHAPTER XXXIV. 



the following for fresh-water Dendroccela : 2 per cent, 

 sublimate solution 6 parts ; 15 per cent, acetic acid, 4 parts ; 

 pure nitric acid, 2 parts ; 14 per cent, chloride of sodium, 8 

 parts ; and 2 per cent, alum, 1 part. Note also the mix- 

 tures of Lang, 67. Mayer's tincture of cochineal, 230, 

 may be found useful for the study of glands, for which 

 purpose the Ehrlich-Biondi stain may also be employed. 



Lo BIANCO (loc. cit., p. 461) kills Rhabdoccela and Dendro- 

 ccela with hot sublimate, throws them at once into cold 

 water, and then brings them into alcohol. For some Poly- 

 clads the sublimate must not be more than slightly warm. 



VOIGT (Verh. Nat. Ver. Bonn, 1896, p. 118) kills Planaria 

 by pouring off the water it is in and inundating it with a 

 mixture of one part concentrated nitric acid and three parts 

 water, and after one minute brings into alcohol of 70 to 90 

 per cent. 



KLINCKOWSTROEM (Arch. mik. Anat., xlviii, 1897, p. 589) 

 fixes Prosthecer&ux in 70 per cent, alcohol with 4 per cent, 

 of acetic acid. 



JAENICHKN (Zeit. wisft. Zool., Ixii, 1896, p. 256) advises 

 for Planaria, eyes especially, picro- sulphuric acid for an 

 hour or two ; 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 pyrolig-ueous acid, on the top of the stove. 

 He macerates the visual rods in a mixture of one part 

 common salt, one of acetic acid, and 100 of water. He 

 bleaches the pigment of the eyes with peroxide of hydrogen. 



Echinodermata. 



860. Holothurioidea. These animals 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. 



S. Lo BIANCO (loc. cit., p. 459) puts them into pure sea 

 water until they have expanded their tentacles, then seizes 

 them with forceps or the fingers behind the tentacles, so as 

 to mechanically render impossible their withdrawal, and 

 immerses the anterior part of the body in acetic acid, whilst 



