MACERATIONS AND CORROSIONS

1 the fatty substance is mixed with some medium        that will
eiVtr- cause it to change places, by diffusion, with the watery com-
Iture  ponents of the tissues. If to one volume of olive oil be added
Ir.  about half a volume of absolute alcohol and a like quantity
thit the  of ether (the exact proportion of ether being that which gives
nocessful  a clear mixture by agitation), a mixture is obtained which has
tomioqs i the property of taking up small quantities of water without
t  undergoing separation into its constituent parts. If small
adorje  portions of tissue be immersed in such a liquid, all those
ad it : constituents of the tissue that are soluble in the oil-mixture
etig, I (namely, first of all its water, then fatty and nervous matters),
iglh jort will be taken up by it, and the oil-mixture will take their place
w of  i in the tissue. If now the latter be thrown into water the
artnljj  alcohol and ether will be taken up by the water, and the oil
wbhf.I thrown down in the tissue. This is then hardened and
the  I blackened with osmic acid and corroded with Aqua Javelli.
lWil, o It must be noticed that this method of impregnation differs
00 rt6  in principle from the ordinary methods of impregnation with
ide te  metallic salts, inasmuch as these depend on chemical affinities,
rfker  whilst the oil-impregnation depends on purely physical pro-
oisnell cesses of diffusion.
rtothe  Second formula (Castor-oil and alcohol).-Instead of the
above-given oil-mixture, it is sometimes advantageous to use
admfoo  the following: 2 parts of castor-oil are dissolved in 1 part of
oo  alcohol.  (Castor-oil being soluble in alcohol, it is unnecessary
go  to add ether.)
ab of  Fresh tissues should always be employed for impregnation.
Small portions should be immersed for from five to eight
when  days in a large quantity of the oil-mixture, then thrown into
W p.  water in order to precipitate the oil, and finally brought for
to, i6  twenty-four hours into a 1 per cent. solution of osmic acid,
lhk of  and finally corroded and mounted in glycerin.
The author describes (1. c.) the results he obtained in the
study of dark-bordered nerve-fibres, muscle-fibres, cartilage,
oo  epithelia, cornea, choroid, retina. He appears to be justified

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