SOME METHODS FOB LOWER ANIMALS. 463 



together with a portion of the tentacle, and fixes by exposing 

 it for some minutes to vapour of osmic acid. He depigments 

 sections by very careful treatment with very dilute eau de 

 Javelle. 



829. Eyes of Cephalopoda and Heteropoda (GRENACHER, Abh. 

 naturf. Ge*. Halle-a.-S., Bd. xvi ; Zeit. f. iciss. Hik., 1885, 

 p. 244). Fix (Cephalopod eyes) in picro-sulphuric acid, or 

 in a saturated solution of corrosive sublimate in picro-sul- 

 phuric acid (this mixture is especially useful for Octopus, 

 Eledone, and Sepia, but does not succeed with the pelagic 

 forms, such as Loligo, Ommatostrephes, and Rossia). Depig- 

 ment the specimens with hydrochloric acid (in preference to 

 nitric acid). The mixture 581 may also be used. The 

 operation of depigmentation may be combined with that of 

 staining ; if you stain with borax-carmine and wash out in 

 the last-mentioned mixture the pigment will be found to be 

 removed quicker than the stain is washed out. The operation 

 may be carried out on sections, but it is better to use portions 

 of retina of 2 to 5 mm. in thickness. Grenacher mounted 

 his preparations in castor oil, see 447. 



Similar methods are recommended by the same author for 

 the eyes of Heteropoda (see Abh. naturf. Ges. Halle-a.-S., 

 1886; Zeit. f. wiss. Mik., 1886, p. 243). 



LENHOSSEK (Zeit. iinss. Zool., Iviii, 1894, p. 636; Arch. mik. Anat., 

 xlvii, 1896, p. 45) applies the method of GOLOI to the eyes of Cephalopods. 



Similarly KOPSCH (Anat. Anz., xi, 1895, p. 362), but using formol instead 

 of the osmic acid. 



830. Eyes of Lamellibranchiata. See PATTEN, Mitth. Zool. Stat. 

 Neapel, vi, 1886, p. 733, and RAWITZ, Jena, Zeit. Naturw., xxii, 1888, 

 p. 115, and xxiv, 1890, p. 579 (bleaches with caustic soda) ; see 584. 



831. Central Nervous System of Pulmonata. B. de NABIAS 

 (Act. Soc. Linn. Bordeaux, 1894; Rech. Hist, centres nerveux 

 de* Gasteropodes, 1894, p. 23) opens the animals and fixes 

 the ganglia for one hour in a mixture of 6 parts glacial acetic 

 acid to 100 of 90 per cent, alcohol, or for fifteen to twenty 

 minutes in 5 per cent, sublimate with 5 per cent, acetic acid. 

 He stains in bulk, with Renaut's haematoxylic eosin, 389, 

 or R. Heidenhain's hsematoxylin, 252, or a copper haema- 



