NEMERTINA. 445 



in terrestrial and fresh-water Planaria, Polyclada, and most 

 Khabdoccela they are better preserved. The same method is 

 also good for the parenchyma of Amphichoerus cinereus, Convo- 

 luta paradoxa, and C. sordida. Sublimate is not good for 

 these forms, but it is good for Convoluta Roscoffensis. For 

 some forms it is important to avoid picro-carmine, which 

 destroys the central parenchyma. The nervous system may 

 be investigated by the methods of DELAGE. 



For Dendroccela sublimate solutions, sometimes hot, appear 

 indicated for fixing. CHICHKOFP (Arch, de BioL, xii, 1892, 

 p. 438; Journ. Roy. Mic. Soc., 1893, p. 262) recommends the 

 following for fresh-water Dendroccela : 2 per cent, sublimate 

 solution, 6 parts; 15 per cent, acetic acid, 4 parts; pure nitric 

 acid, 2 parts ; 14 per cent, chloride of sodium, 8 parts ; and 

 2 per cent, alum, 1 part. The animals are said to die in it with- 

 out contraction. Note also the mixtures of LANG, 48. The 

 staining method of that author with picro-carmine and borax- 

 carmine (Fauna u. Flora d. Golfes von Neapel [Polycladidea'], 

 1884, p. 30) seems to be now somewhat antiquated. Mayer's 

 tincture of cochineal, 172, may be found useful for the study 

 of glands, for which purpose the Ehrlich-Biondi stain should 

 also be employed. 



835. Nemertina. After considerable experience of this 

 difficult group I have to say that I know of no method of 

 fixation that will certainly give good results. My best results 

 have always been obtained with cold saturated sublimate 

 solution, acidified with acetic acid. I have tried most of the 

 energetically hardening fixing agents, such as the osmic and 

 chromic mixtures, and do not recommend them for this 

 group, for they seem (the chromic mixtures and perchloride 

 of iron in particular) to act as irritants, and provoke such 

 violent muscular contractions that the whole of the tissues 

 are crushed out of shape by them. And, besides, they do 

 not kill as quickly as sublimate. 



I have found it a good plan to decapitate the animals (in 

 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 



