698 Methods of Microscopical Research [Se 



important to remember what kind or kinds of work eac 

 expected to accomplish. 



Kleinenberg's picro-sulphuric acid, for instance, now 

 used in the Naples Aquarium, is not a hardening fluid, 

 for killing, and thus prepares for subsequent hardening. 



I. Kleinenberg's Fluid} — 



Filter the mixture and dilute it with three times its bulk of water; 2 

 finally add as much creosote 3 as will mix. 4 



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, alcohol, where they may remain 5-6 hours. They are 

 next placed in 90 per cent, alcohol, which must be changed at 

 intervals until the yellow tint has wholly disappeared. 



Summary of Dr. Mayer s remarks on Kleinenberg's Fluid.— The 

 advantages 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 be wholly replaced by alcohol. In this latter fact lies the 

 superiority of the fluid over osmic and chromic solutions, all of 

 which produce inorganic precipitates and thus leave the tissues in 

 a condition unfavorable to staining. Picro-sulphuric acid does not, 

 like chromic solutions, harden the object, but simply kills the 

 cells. 



. As this fluid penetrates thick chitine with difficulty, it is neces- 

 sary, in order to obtain good preparations of larger Isopoda, in- 

 sects, &c, to cut open the body and fill the body-cavity with the 

 liquid by means of a pipette. In larger objects care should be 

 taken to loosen the internal organs so that the fluid may find easy 



The fluid should be applied as soon as the body is opened, so 

 that the blood may not have time to coagulate and thus bind 



