504 METHODS FOR INVERTEBRATES. 



mended by DROST (Morphol. Jahrb., xii, 1866, p. 163) for 

 Cardium and My a. 



PATTEN (Mitth. Zool. Stat. Neapel, vi, 1886, p. 736) takes sulphuric 

 acid, 40 drops to 50 grms. of water. Entire molluscs, without the 

 shell, may be kept in it for months. 



BERNARD (Ann. Sci. Nat., ix, 1890, p. 191) macerates the mantle 

 of Prosobranchs in a mixture of 1 part each of glycerin and acetic 

 acid, 2 parts each of 90 per cent, alcohol and 0-1 per cent, chromic 

 acid and 40 parts water, which acts in from a quarter of an hour to 

 three hours. He also (pp. 102, 306) uses a weak solution of chloride 

 of ruthenium, especially for nerve-tracts, mucus-cells and cilia. 

 Alcohol material may be macerated in a mixture of 1 part. glycerin, 

 2 of acetic acid and 40 of water. 



941. Mucus Glands. RACOVITZA (Arch. Zool. exper. [3], ii, 1894, 

 p. 8) studies these in Nudibranchs (and Annelids) by killing with 

 acetic acid, staining in toto with methyl green dissolved in liquid 

 of RIPART and PETIT, and after three to six days, when only the 

 glands show the stain, examining in mixture of equal parts of 

 glycerin and the liquid. 



Arthropoda. 



948. General Methods for Arthropoda. As general methods for 

 the study of chitinous structures, the methods worked out by Paul 

 Mayer (see 8, 96 and 97) are excellent. It is, at all events, absolutely 

 necessary, in the preparation of entire organisms or unopened organs, 

 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 pier o -sulphuric acid 

 (or picro-nitric) is the most generally useful fixative, and 70 per cent, 

 alcohol is the most useful strength for washing out. Alcoholic picro- 

 sulphuric acid may be indicated for fixing in some cases. 



But if the animals or organs can first be properly opened, the 

 usual methods may be employed. 



942A. Mounting Small Arthropods. Dr. A. D. Imms informs me 

 that for mounting and clearing aphids and other small insects, etc., the 

 following formula as used by Professor Beiiese for Acarina gives good 

 results : 



H 2 ....>.. 20grs. 

 Chloral hydrate . . . . 160 ,, 



Gum arable . . . . . 15 ,, 



Glucose syrup . . . . . 10 ,, 



Acetic acid . . . . . . 5 



