THE PREPAEATION OF ANIMAL TISSUES. 47 



testes of the newt should be placed in the solution 

 for twenty-four hours, then cut into, and their 

 contents squeezed out on to a slide. The sperma- 

 tozoa are thus obtained as a permanent preparation. 

 Another important use of the above solution has 

 been pointed out by Heidenhain. If small pieces of 

 kidney be placed in the solution for forty-eight 

 hours (the cortex should be chosen), the preparation 

 shows the cells of the uriniferous tubules and their 

 peculiarities as no other method, probably, will 

 show them. 



Miiller's Fluid. 



This is made by dissolving twenty-five grms. of 

 potass, bichrom. and ten grms. sodse sulph. in 1000 

 c.c. of water. 



Miiller's fluid has great penetrating power. It 

 hardens slowly, taking, it may be, from five to seven 

 weeks. It is useful as a commencing agent, to 

 be followed by another of greater shrinking power, 

 such as chromic acid and spirit solution, ordinary 

 alcohol, &c. Very even shrinkage may thus be 

 obtained. For example, if the fresh nasal septum 

 is cut out and placed for two days in Miiller's fluid, 

 then for a week in chromic acid and spirit solution, 

 afterwards in weak, then in pure methylated spirit, 

 the olfactory epithelium will be obtained in excel- 

 lent preservation. 



After the above explanation no difficulty will be 



found with the following delicate structures, namely: 



Developing tooth, the adenoid tissue of lymphatic 



gland, spleen, thyroid gland, supra-renal-capsules 



(of the horse, by preference), sympathetic ganglion, 



