GENERAL METHODS FOR ARTHROPODA. 439 



per cent, (after having warmed the animal for a short time to 

 45 to 50 C.). Also, concentrated boracic acid solution. 



The Intra-cellular Processes of the Cilia. The entire intra- 

 cellular fibre apparatus may be isolated by teasing fresh epi- 

 thelium from the intestine of a Lamellibranch (e. g. Anodonta) 

 in either bichromate of potash of 4 per cent., or salt solution 

 of 10 per cent. To get good views of the apparatus in situ in 

 the body of the cell, macerate for not more than an hour in 

 concentrated solution of boracic or salicylic acid. Yery 

 dilute osmic acid (e. g. Ol per cent.) gives also good results. 

 The " lateral cells " of the gills are best treated with strong 

 boracic acid solution (5 parts cold saturated aqueous solution 

 to 1 part water). 



BELA HALLER'S Mixture, see 543. 



BROCK'S Medium, 538. 



MOBIUS'S Media, 539 ; the second of these is much re- 

 commended by DROOST (Morphol Jahrb., xii, 2, 1886, p. 163) 

 for Cardium and My a. 



See also the media recommended by PATTEN (Mitth. Zool. 

 Stat. Neapel, vi, 4, 1886, p. 736). Sulphuric acid, 40 drops 

 to 50 grammes of water, is here recommended as a most 

 valuable macerating and preservative agent. Entire molluscs, 

 without the shell, may be kept in it for months. 



Arthropoda. 



822. General Methods for Arthropoda. It may safely be 

 stated that, as general methods for the study of chitinous 

 structures, the methods worked out by Paul Mayer (see 4 

 and 5, and also 57 and 172) are superior to all others. It is 

 absolutely necessary that all processes of fixation, washing, 

 and staining should be done with fluids possessing great 

 penetrating power. Hence picric acid combinations should 

 in general be used for fixing, and alcoholic fluids for washing 

 and staining. Concentrated picro-sulphuric acid is the most 

 generally useful fixative, 70 per cent, alcohol is the most 

 useful strength for washing out, and tincture of cochineal in 

 alcohol of 70 per cent. ( 172) is a very generally useful 

 staining fluid. Mayer's haemacalcium ( 182) may some- 

 times be preferable, and alcoholic carmine and borax-carmine 

 will occasionally give more satisfactory results. 



