ON THE METHODS OF MICROSCOPICAL RESEARCH 

 IN USE IN THE NAPLES AQUARIUM. 



SUMMARY (By GEO. BROOK, F L.S.) or a Paper by Dr. Paul Mayer, in 



THE "MlTTHEILUXGEX A. D. ZoOLOG. StATIOX, ZU NeAPEL," VOL. 2, PART 1, 1880. 



Dr. Dohrn's Geological station at Naples, including as it does every 

 facility for dredging and studying marine fnrms, has commenced a 

 new era in the study of marine biology which cannot be too closely 

 imitated in this country. The methods employed in this establish- 

 ment in preserving the objects to be studied, the various processes 

 by which they are stained, mounted, &c., cannot fail to be of interest 

 to every working microscopist, for although the methods here 

 enumerated are only mentioned in connection with marine forms, 

 they are as a rule equally applicable to fresh-water organisms, insects, 

 &c. It is for this reason that I have ventured to lay before the 

 readers of the Naturalist a summary of Dr. Mayer's paper. 



PRESERVATIVE METHODS. 

 Picrosulphuric Acid. — First in importance as a preservative 

 medium, and one which is now becoming most generally used, is 

 picrosulphuric acid. Kleinenberg's formula for preparing it is as 

 follows : — 



100 parts cold saturated solution of picric acid in water ; 

 2 „ strong sulphuric acid. 



The liquid, when filtered and diluted with three times its bulk of 

 water, is ready for use. For Arthropoda Dr. Mayer uses the acid 

 undiluted. 



One of its greatest advantages is that it supplants the water 

 in the animal's body, as well as that adhering to its outer surface by 

 a liquid which, after having done its work, allows itself to be entirely 

 replaced by alcohol. With osmic and chromic solutions, it is well 

 known this is not the case. They also produce an inorganic precipi- 

 tate in the tissues of the objects which prevents proper staining 

 afterwards. With picro-sulphuric acid it is necessary to use plenty 

 of the liquid, particularly for objects with a large body cavity, which 

 it is necessary to preserve whole. It penetrates with difficulty 

 through thick chitine, though even in this respect it is preferable to 

 other media. With the larger objects it is indispensable to open the 

 body its whole length with a pair of scissors, and by means of a 

 N. S., Vol. vi.— Junr, 1881. 



