618 INVERTEBRATES 



PORIFERA 



1231. Spongiae : Fixation. The smaller forms can be fairly 

 well fixed by the usual reagents, osmic acid being one of the 

 best. For the larger forms absolute alcohol is apparently the 

 best. If any watery fluid be preferred, care should at all events 

 be taken to get the sponges into strong alcohol as soon as possible 

 after fixation, on account of the rapidity with which maceration 

 sets in in watery fluids. Fiedler {Zeit. wiss. ZooL, xlvii, 1888, 

 p. 87) has been using (for Spongilla), besides absolute alcohol, an 

 alcoholic sublimate solution and the liquids of Kleinenberg and 

 Flemming. 



1232. Staining. To avoid maceration, Lee held that alcoholic 

 stains should be alone employed, and recommended Mayer's 

 tincture of cochineal, § 249. Von Lendenfeld {Zeit. wiss. 

 Mik., xi, 1894, p. 22) uses aqueous solutions of Congo red and 

 anilin blue for the coloration of collar-cells. 



MiNCHiN (Quart. Joiirn. Mic. Sci., xl, 1898, p. 569) stains 

 spicula sheaths with Freeborn's picro-nigrosin, p. 353. 



Rousseau {Ami. Soc. Belg. Mic, xxiv, 1899, p. 51) stains in 

 nigrosin, picro-nigrosin, or indulin. or Mayer's picro-magnesia 

 carmine. 



Prof. Dendy infoimed us that he used Hickson's brazilin 

 (§ 417) a great deal in his work on sponges. 



F^or intra -vitam staining, see Liosel, see last ed. 



For silvering, see § 387. 



Sectioning. Calcareous sponges may be decalcified in alcohol, 

 acidified with hydrochloric or nitric acid, and then imbedded in 

 the usual way. Siliceous sponges may be desilicified, § 610. 



For Rousseau's methods, see § 610. Vosmaer and Pekel- 

 HARING decalcify with a solution of picric acid in absolute alcohol 

 (see Zeit. rviss. Mik., xv, 1899, p. 462). 



See also Johnstone-Lavis and Vosmaer, § 204. 



Preparation of Hard Parts. Siliceous spicules are easily cleaned 

 by treating them on a slide with hot concentrated nitric or hydro- 

 chloric 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 § 612. 



Embryos and Larvae. Maas {Zool. Jahrb., Abth. Morph., vii, 

 1894, p. 334) fixes larvte 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. wiss. 



