Acefone as a Solvent for Mounting Media. 281 



Action on Stains. — The medium seems to have very little effect 

 on borax or lithium carmine, or on acid stains sucli as Van Giesen's ; 

 or on haimatoxylin, mordanted previously with a 4 p.c. iron-alum 

 solution, and reduced after staining in ^ to 1 p.c. iron-alum solution ; 

 but I find that if ha^n)atoxylin is used as recommended by G, E. 

 La Rue,* the blueing of the stain is affected, if the slide is heated, 

 by again becoming reddish in colour, as if in an acid bath. In 

 some ways, however, this is an advantage, as the heating of the 

 preparation can be stopped at a time when some particular struc- 

 ture becomes prominent, giving a double-stain effect which is 

 unaltered by the acetone-balsam, even after six months. I have 

 also tested the action of the medium on blood-smears stained with 

 Jenner, Giemsa, and Leishman (Soloid brands). The two former 

 did not retain the stain for any length of time, but whether due to 

 a faulty stain or the medium I cannot be sure ; however, with 

 Leislunan's the staining was quite as brilliant in media (a) and (h) 

 three months after as when first mounted. I also find that blood- 

 smears and some of the sporozoa, such as Myxololas csmarJiii 

 Woodcock,t which I have obtain'ed frequently from the sclerotic 

 coat in the eye of haddocks (Gadus mjlefimis), retain Ehrlich's 

 triacid stain (Cabot's formula) when mounted in either of the 

 variations («) or (h). 



Some Advantages of tlte Method : — 



1. It clears specimens from various grades of alcohol direct 



without the use of essential oils. 



2. It does not cause a precipitate or any uneven shrink- 



age on the tissues of specimens where these have 

 been properly fixed. 



3. It has the advantage that specimens may be oriented 



in any desired position nnder the cover-glass and 

 kept there until the exchange to the mounting 

 medium is completed. 



4. Many variations are possible in the miking-up and 



employment of medium without fundamental change 

 in the result. 

 The work was carried out at my own house, but I have to 

 express my indebtedness to Dr. James F. Gemmill, of the Univer- 

 sity, Glasgow, for advic3 and encouragement he has given me in 

 the preparation of this paper, and also for placing at my disposal 

 .some re-distilled acetone free from acid, which other .vise I would 



* " A Revision of the Cestode Family Proteocepbalidse." Illiuois Biological 

 Monographs, i. (1914) pp. 1.5, 16. 



t Considered by Dr. Jas. Johnstone, to whom I sent specimens, to be 

 Myxobohis esmarkii Woodcock ; and if so, now recorded for a new host, the previous 

 Report being Johnstone's, from Gadus esmj,rkii, in Lancashire Sea Fisheries 

 record for 1906. 



U 



