MACERATION AND DIGESTION. 313 



Zeit. f. wiss. Mik., vii, 4, 1891, p. 461) by melting white wax 

 and stirring into it one half to two thirds of Venice turpen- 

 tine. Care must be taken if the operation be performed over 

 a naked flame, as the turpentine vapours are inflammable. 



518. Iodised Serum ( 392). The manner of employing it 

 for maceration is as follows : A piece of tissue smaller than 

 a pea must be taken, and placed in 4 or 5 c.c. of weakly 

 iodised serum in a well-closed vessel. After one day's 

 soaking the maceration is generally sufficient, and the 

 preparation may be completed by teasing or pressing out, 

 as indicated above ; if not, the soaking must be continued, 

 fresh iodine being added as often as the serum becomes pale 

 by the absorption of the iodine by the tissues. By taking 

 this precaution the maceration may be prolonged for several 

 weeks. 



These methods are intended to be applied to the prepara- 

 tion of fresh tissues, the iodine playing the part of a fixing 

 agent with regard to protoplasm, which it slightly hardens. 



519. Artificial Iodised Serum ( 394). RANVIER has been 

 unable to obtain good results, for purposes of maceration, 

 with it. 



520. Alcohol RANVIER employs one third alcohol (1 part 

 of 90 per cent, alcohol to 2 parts of water). Epithelia will 

 macerate well in this in twenty-four hours. RANVIER finds 

 that this mixture macerates more rapidly than iodised 

 serum. 



Other strengths of alcohol may be used, either stronger 

 (equal parts of alcohol and water) or weaker (J alcohol, for 

 isolation of the nerve-fibres of the retina, for instance 

 THIN). 



All observers are agreed that one third alcohol is a mace- 

 rating medium of the highest order. 



521. Salt Solution. 10 per cent, solution of sodium chloride 

 is a well-known and valuable macerating medium. 



522. MOLESCHOTT and Piso BORME'S Sodium Chloride and 

 Alcohol (MOLESCHOTT'S Untersuchimgen zur Naturlehre, xi, pp. 



