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METHODS IN PLANT HISTOLOGY 
JEFFREY’S MACERATION METHOD 
A method which I saw at Toronto and which gives much better 
results was credited to Professor Jeffrey. Wood is cut or split into 
sections about 300 ju thick, which are then boiled and cooled until 
free from air. The macerating fluid consists of equal parts of 10 per 
cent nitric acid and 10 per cent chromic acid. The time will vary 
with different woods, but is likely to be about 24 to 48 hours if the 
temperature is about 35° C. When properly macerated the cells may 
be shaken apart or are very easily teased apart. Before staining, 
the material should be very thoroughly washed to remove the acid. 
A study of such material is very valuable in modern anatomical work. 
Maceration methods which act in a few minutes are likely to be 
so violent that fine details will not be preserved. 
PROTOPLASMIC CONNECTIONS 
As a rule, protoplasmic connections are not likely to be seen in an 
ordinary preparation. It used to be thought that the rather large 
protoplasmic strands seen at the sieve plates of the pumpkin and other 
Cucurbitaceae were exaggerated examples of protoplasmic continuity; 
but, as a matter of fact, the large strands do not extend entirely 
through the plate. The real continuity, through the middle lamella, 
is scanty and hard to demonstrate. 
Very satisfactory material for the demonstration of the connecting 
strands is furnished by the seeds of the Japanese persimmon, Diospiros 
Kaki. Fix in formalin alcohol (10 c.c. formalin to 50 c.c. of 70 per cent 
alcohol) or in a mixture of equal parts 70 per cent alcohol and glycerin 
(Fig. 27). 
Good views of the strands are most abundant in sections cut 
parallel with the flat surface of the seed. No imbedding is either 
necessary or desirable. Clamp the seed in the microtome directly, 
or fasten it to a wooden block with cellulose acetate (easily made by 
dissolving a photographic film in acetone; of course the emulsion 
should be removed), with celloidin, or even with glue. Cellulose ace¬ 
tate seems to be the best. Cut sections 8 to 12 p thick; place them 
in ether several hours to remove any fatty substances; remove the 
ether with absolute alcohol; transfer to 95 per cent alcohol, then to 
50 per cent alcohol, and then to water. Stain in iron-alum haema- 
toxylin. The following schedule for Diospiros Kaki will introduce 
the method. 
