ACANTHOOEPHALI. 365 



the larger forms), cut them up quickly into lengths (not too 

 long), and throw these sharply into the sublimate, the mus- 

 cular contractions being less energetic in segments that are 

 no longer in connection with the cerebral ganglia. 



Perhaps a better method than this will be found in the 

 simple process, suggested to me by Prof. DUPLESIS, of fixing 

 with hot (almost boiling) water. On the few occasions on 

 which I have tried it, the animals have died in extension, 

 without vomiting their proboscis ; and I think it is certainly 

 worth trial, especially for the larger forms. 



I have tried FOETTINGER'S chloral hydrate method ( 14) ; 

 my specimens died fairly extended, but vomited their pro- 

 boscides. 



DE CASTELLARNAU (Estacion Zool. de Napoles, p. 137) says 

 that Nemertians can be successfully narcotised by Eisig's 

 alcohol method, described 13. 



For staining in toto I hold that it is absolutely necessary 

 to employ alcoholic stains, for even the most delicate species 

 are not satisfactorily penetrated by watery stains in any 

 reasonable lapse of time. Borax-carmine or Mayer's alco- 

 holic-carmine may be recommended; not so cochineal or 

 haDmatoxylin stains, on account of the energy with which they 

 are held by the mucin which in general exists in such great 

 abundance in the skin of these animals. 



Sections by the paraffin method, after penetration with oil 

 of cedar (chloroform will fail to penetrate sometimes after 

 the lapse of weeks) . 



729. Nematodes. The extremely impermeable cuticle of 

 these animals is a great obstacle to preparation. According 

 to Looss (Zool. Anz., 1885, p. 318) this difficulty may be over- 

 come by treating the animals (or their ova, which are in the 

 same case) with eau de Javelle or eau de Labarraque, in the 

 manner described in 529. 



BRAUN (see Journ. Roy. Mic. 8oc., 1885, p. 897) recommends 

 that small unstained Nematodes be mounted in a mixture of 

 20 parts gelatin, 100 parts glycerin, 120 parts water, and 2 

 parts carbolic acid, which is melted at the moment of using. 



730. Acanthocephali. It is very difficult to kill Echinorhynci 

 so as to have the animals duly extended and the tissues well 

 preserved. Neither corrosive sublimate nor strong osmic 



