ACETIC ALCOHOL. 283 



it may safely be stated as a general rule that if you take the 

 strong mixture, and fix thoroughly in it, you are not likely to 

 go far wrong. And what is meant by a thorough fixation ? 

 Half an hour may be taken to be generally enough ; but for 

 very delicate things, such as the Nebenkern and the achro- 

 matic figure, at least eighteen hours ought to be given. 



It only remains to point out that this doctrine is at variance 

 with that expressed in the first edition and in the Traite, and 

 with the earlier recommendations of Flemming ; but I feel 

 some confidence that it will not be called in question by the 

 majority of workers at this subject. Of course it goes without 

 saying that further precise evidence on the matter is very 

 much to be desired. 



Two or three of the fixing agents proposed by other writers 

 fix quite as faithfully as Flemming's mixture. There is 

 RABI/S chromo-formic acid ( 32). Fix in this for twelve to 

 twenty-four hours, wash out well with water, and pass into 

 alcohol. And there is the same observer's platinum chloride 

 solution ( 47). In Rabl's latest communication (Anat. Anz., 

 iv, 1889, p. 21) he recommends that Salamandra larvae be 

 fixed (for twenty-four hours) in a solution of from one tenth 

 to one eighth per cent, strength. In his earlier work he used 

 solutions of 1 300 strength. Platinum chloride has the 

 peculiarity of causing a slight shrinkage of the chromatin, 

 which helps to bring into evidence the granules of Pfitzner 

 and the longitudinal division of the chromosomes. 



. Acetic Alcohol is a reagent with which some of the most im- 

 portant work in recent cytology has been done namely, much 

 of that on the maturation and fecundation of the ovum of 

 Ascaris. 



CAENOY (La Cellule, iii, 1, 1886, p. 6) used at first a mixture 

 of three parts of absolute alcohol with 1 of glacial acetic 

 acid; later (ibid., iii, 2, 1887) the chloroform mixture ( 52). 

 From five to fifteen minutes is enough for even the most re- 

 sistent ova. 



VAN BENEDEN and NEYT (Nouvelles Eech. sur la Fee. et la 

 Division mitosique, 1887) employed a mixture of equal parts of 

 absolute alcohol and glacial acetic acid, or even pure acetic 

 acid. 



Acetic alcohol may be washed out with either pure alcohol, 



