ME'I'HODS FOB INVEllTEBIiATES. 475 



nitric or liydrocliloric acid, or solution of potash or soda. 

 The acids mentioned are very efficient, but may attack the 

 silex of some delicate spicules. Potash solution is, therefore, 

 frequently to be preferred, notwithstanding that, in my 

 experience, it does not give such clean preparations. 



According to Noll, eau de Javelle is preferable to any of 

 these reagents, see § 552. 



Embryos and Larvae, — Maas {Zool. Jahrb.,Ahth. Moyph.,vu, 

 1894, p. 334) fixes larvae in liquid of Flemming or Hermann, 

 one to three minutes, and stains with borax-carmine, or with 

 gentian violet and Orange G (Flemming). He also [Zeit. 

 u'iss. Zool., Ixvii, 1900, p. 218) fixes young Sycones in abso- 

 lute alcohol and stains with ammonia carmine (spicules in 

 situ) . 



DfLAGE [Arch. Zool. Exper., x, 1892, p. 421) fixes larvte 

 of Spongilla that have settled down on cover-glasses for three 

 minutes in absolute alcohol, stains in alcoholic carmine, § 234a, 

 and brings through alcohol into oil of bergamot, then either 

 mounts direct in balsam, or detaches the larvse from the cover 

 and imbeds in paraffin (three minutes). 



Protozoa. 



916. Introductory. — The reagents and methods of cytology 

 are in great part applicable to this group. One of the most 

 generally useful of these reagents will be found in the acid 

 solution of methyl green; it is the reagent that allows of the 

 readiest and best demonstration of the presence and form 

 of the nucleus and nucleolus (Balbiani et Henneguy, Compt. 

 revd. Sac. de Biol, 1881, p. 131). 



Weak solutions of alum, potash, and borax serve to 

 demonstrate the striations of the cuticle, and the insertions 

 of the cilia of Infusoria. 



BcHUBEEG {Arch. Protisttiik., vi, 1905, p. 63) stains cilia by 

 the GoLGi impregnation (will bear a covei') ; or by Loefflee's 

 stain for flagella (fix with vapour of osmium, the rest under 

 a cover). 



For the mitochondria of Protozoa, see Fauee-Fhemiet, 

 Arch. d'Avat. micr., xi, 1910, p. 457 [intra-viiam stains for 

 them. Dahlia in salt solution or PiCiE'i's liquid being the 

 best). 



