616 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [10] 



for tlie action of the fluid. Dr. Eisig has used this fluid with great suc- 

 cess iu i)rep!iring the (U^licate hiteral organs of the CapiteJHd(v for sec- 

 tions, and recommends it strongly for other annelids. Dr. Eisig allows 

 objects to remain three to five hours in the fluid, then transfers to 70 per 

 cent, alcohol. With small leeches I have found one hour quite sufficient, 

 and transfer to 50 per cent, alcohol." 



Whitman gives the following account of Kleinenberg's picro-sulphuric 

 acid, now so much used in the Naples Aquarium. It is not a hardening 

 fluid, and serves for Jcilling, and thus prepares for subsequent harden- 

 ing. 



FerenyPs fluid. — This recently introduced hardening agent is com- 

 pounded as follows : 



Nitric acid (10%) 4 parts. 



Alcohol (90%) 3 " 



Chromic acid (4%) 3 " 



Objects are left iu this fluid from four to five hours, then transferred 

 for twenty-four hours to 70 per cent, alcohol ; then to 90 per cent, alco- 

 hol ; and finally to absolute alcohol, in w^hich they remain for four to 

 five days. 



Picro-carmine or boraxcarmiue are added directly to the fluid, so 

 that the hardening and staining of the objects take place simultane- 

 ously. The precipitates which are produced when the reagent is mixed 

 with the coloring solutions should be removed by filtration before the 

 objects to be hardened are introduced. Eggs and embryos prepared in 

 this mixture are said to cut like cartilage. 



'■^Kleincnherg's Huid. — Picric acid (saturated solution in distilled water), 

 100 volumes ; sidphuriG acid (concentrated), 2 volumes. Filter the mix- 

 ture and dilute it with three times its bulk of water.* Finally add as 

 much creosotet as will mix.| 



" Objects are left in the fluid three, four, or more hours, and are then, 

 in order to harden and remove the acid, transferred to 70 per cent, alco- 

 hol, w'here they may remain five to six hours. They are next placed in 

 90 per cent, alcohol, which must be changed at intervals until the yellow 

 tint has wholly disappeared. 



" Snminart/ of Dr. Mayer'>s rcmarJcs on Klcinenl)er(fs fluid. — The advan- 

 tages of this fluid are, that it kills quickly, by taking the place of the 

 water of the tissues ; that it frees the object from sea water, and the 

 salts contained in it, and that having done its work it may he iphoUy re- 

 'placed by alcohol. In this latter fact lies the superiority of the fluid over 

 osmic and chromic solutions, all of which ])rodu(;e inoiganic i)recipitates, 

 and thas leave the tissues in a condition unfavorable to staining. Picro- 



* Dr. Mayer uses the fluid nndilnted for arthropoda. 



t Creosote made from beechwood tar. 



^ Dr. Mayor prepares the llnid asfoUows: Distilled water, 100 volumes; sulphuric 

 acid, 2 volumes ; picric acid (as uiucli as will dissolve). Filter and dilute as above. 

 No creosote is used. 



