454 SOME ZOOLOGICAL METHODS. 



are better studied by fixing with osmic acid, staining with 

 Beale's carmine, and mounting in glycerin. 



Larvae of Comatula. The best method for the study of the 

 embryonal development of Comatula consists in fixing with 

 liquid of Lang, and staining with dilute borax-carmine. It 

 is important (for preparations that are not destined to be 

 sectioned) to use only dilute borax-carmine, as the strong 

 solution produces an over-stain that cannot easily be reduced. 



Narcotisation by chloral hydrate before fixing is useful, 

 especially for the study of Pentacrinus larvae and of the young 

 Synaptse formed from Auricularia. Without this precaution 

 you generally get preparations of larvae either shut up 

 (Pentacrinus), or entirely deformed by contraction (young 

 Synaptse} . 



See also MACBRIDE on the development of Amphiura squa- 

 mata } Quart. Journ. Mic. Sci., xxxiv, 1892, p. 131 ; Journ. Roy. 

 Mic. Soc., 1893, p. 117 (osmic acid followed by liquid of 

 Miiller and alcohol ; decalcification with nitric acid in alcohol ; 

 staining with Mayer's paracarmine or haemalum). 



849. Anthozoa. Narcotisation. For suitable narcotisation 

 methods see 9 to 19, and 811. 



Fixation. In LeAttinie. Fauna u. Flora d. Golfes v. Neapel 

 the following hints are given : Hot corrosive sublimate often 

 gives good results. In the case of the larger forms the solu- 

 tion should be injected into the gastric cavity, and a further 

 quantity of the liquid be poured over the animals. 



Freezing sometimes gives good results. A vessel containing 

 Actinias is put into a recipient containing an ice-and-salt 

 freezing mixture and surrounded by cotton wool. After 

 freezing, the block of ice containing the animals is thawed in 

 alcohol or some other fixing liquid. 



The Zoantharia with calcareous skeletons are difficult to 

 deal with on account of the great contractility of the polyps. 

 Sublimate solution, which ought very often to be taken boil- 

 ing, sometimes gives good results. DE CASTELLARNAU (LaEst. 

 Zool. de Napoles, p. 132) says that this process succeeds well 

 with Dendrophyllia, Antipathes, Astroides, Cladocora, and 

 Caryophyllia. 



The Alcyonaria have also extremely contractile polyps. 

 In the last edition I suggested for their fixation either hot 



