530 SUMMARY OF CURRENT RESEARCHES RELATING TO 



(8) Eosin and Logwood. — Here, again, eosin is the ground colour. 

 This combination does very well for the cerebrum. Its general sub- 

 stance becomes stained with the eosin, while the logwood gives the 

 nerve-cells a lilac or logwood tinge. 



(9) Gold Chloride and an Aniline Dye. — Dr. Stirling corroborates 

 Dr. H. Gibbes' views as to the value of this combination. The tissue 

 must first be impregnated with gold chloride, and then stained with 

 either aniline blue, iodine green, or a red dye such as rosein. The 

 tail of a young rat, containing so many different structures, is an 

 excellent material. Eemove the skin from the tail, and place pieces 

 one inch long into the juice of a fresh lemon for five minutes, and 

 afterwards wash them to get rid of the acid. The fine tendons swell 

 up under the action of the lemon-juice, and thus permit the more 

 ready access of the gold chloride. Place the tissue for an hour or an 

 hour and a half in a 1 per cent, solution of gold chloride ; remove it 

 and wash it thoroughly, and place it in a 25 per cent, solution of 

 formic acid for twenty -four hours, which reduces the gold. During 

 the process of reduction the tissue must be kept in the dark. The 

 osseous tissue has then to be decalcified in the ordinary way, with a 

 mixture of chromic acid and nitric acid. After it is decalcified pre- 

 serve the tissue in alcohol. Transverse sections of the decalcified 

 tail are made, and they may be stained with a red dye, such as an 

 alcoliolic solution of rosein, and afterwards with a watery solution of 

 iodine green ; mount them in dammar. 



Preserving Confervse and Desmids.* — The following solution 

 has been found by P. Petit to be the best adapted for preserving 

 the natural green colour of the chlorophyllian Algas (Confervse and 

 Desmids), it having occurred to him that success might be attained by 

 applying to Algte the process made use of in commerce for preserving 

 the green colour of vegetables. 



The basis of the solution is " Eipart's fluid," f and, by the 

 addition of a copper salt, the tendency of that preparation to destroy 

 th<: chlorophyll is overcome. 



gr. 



Camphorated water 50 • 



Distilled water 50- 



Crystal] iziible acetic acid 0*50 



Crystallized chloride of copper 0-20 



„ nitrate „ 0-20 



Dissolve and filter. 



Preparations made in this liquid have preserved the brilliancy of 

 their green hue, even after a year's exposure to the full daylight. 

 Spirogyra, Ulotlmx, and, above all, Desmids {Fenium Ncegeli and 

 Micrasterias crenulata) have thus been preserved in all their fresh- 

 ness. 



Preserving Marine Algse.J — Mr. C. J. Jones describes the follow- 

 ing method which he adopts for preserving the colour of marine algse. 



* ' Brehissonia,' iii. (1880) p. 92. 



t See Cornu and Rivet, ' Dts Pre'parations microscopiques,' Paris, 1872. 



i 'Northern Microscopist,' i. (1881) pp, 51-6. 



