AGf~ICULTURAL RESEARCH, PUSA.

STA [NTNG JlfR7'TlO])S ]70
cent., aml later to 70 per cent. alcohol to which sllflident
iodine lms been added to make the fluid dark brown in colour.
(It is convenient to keep a saturated solution of iocline in
90 per cent. alcohol in a drop bottle, and add a few drops as
required.) If the alcohol becomes dear more iodine is added
until the fluid remains brown. '1'his indieates that uU the
corrosive sublimate has been dissolved out by the ioclinealcohol.
Cut sections fixed on slides can also be treated with iodinee.g.
Gram's iodine-for three to five minutes, to remove mercuric
chloride.
Animal tissues fixed in Zenker'S fluid are more difficult to
cut, and sections are apt to float off the slide, particularly if
fixation has been unduly prolonged.
ZENKER-FORMOL FLUID
This is similar to Zenker's fluid except that the acetic ncid is
omitted and 5 C.c. of strung formalin arc added pel' 100 e.e. immediately
before usc. It is a uscful gcncm.! fixativc for animal
tissues.
MERCURIC CHLORIDE-FORMALIN SOLUTION
Mercuric chloride saturatcd aqueous solution 1)0 c.c.
Formalin, commercial 10 c.c.
Small portions of tissue must be used and fixation is complete
in one to twelve hours. Then transfer to alcohol and iodine
as after Zenker's fluid (q.'1J.). '1'his fluid fixes with the minimum
amount of distol'tion and the finer cytological details of the
cells arc retained.
EMBEDDING AND SECTION CUTTING
After fixation by any of the previous methods and
transference to 50 per cent. alcohol, small pieces of
tissue are treated as follows :-
(1)
(2)
(3)
(4)
(5)
Place in 90 per cent. spirit for two to five hoUl's.
Transfer to absolute alcohol for two haUl'S.
Complete dehydration in fresh absolute alcohol
for two hours.
Transfer to a mixture of absolute alcohol and
chloroform (equal parts) till tissue sinks, or
overnight.
Place in pure chloroform for six hours.