344 
The Ohio Naturalist. 
[Vol. V, No. 7, 
THE AGAR-AGAR AND PARAFFIN METHOD FOR IMBED- 
DING PLANT TISSUES. 
Harlan H, York. 
In the Journal of Applied Microscopy and Laboratory Meth- 
ods 0; 2.391-2, 1903, the writer gave an account of a method for 
killing and imbedding plant tissues in a hot solution of agar-agar. 
While this method is applicable for most histological work, sec- 
tions cannot always be obtained as thin as are sometimes desired. 
Recently a method for imbedding and sectioning plant tissues 
in paraffin after they had been killed and imbedded in a hot 
agar-agar solution was tried. 
The following are some of the sections made by the agar-agar 
and paraffin method : Sections of leaf of date palm ; sections of 
leaf of Ficus elastica; sections of stem of Begonia; sections of 
stem of Equisetum arvense ; sections of leaf of beech ; sections of 
a Uromyces on Sparganium eurycarpum; sections of a Phylla- 
chora on Panicum; sections of a rust on Scirjjus. 
The tissues were first killed and imbedded in a 2 per cent and 
.3 per cent solutions of agar-agar and then imbedded in paraffin 
in the usual way. 
The 2 per cent solution of agar-agar can be made as follows; 
Take 10 grams of agar-agar to .300 c. c. of distilled water and boil 
for two hours. An ordinary oat-meal cooker can be u'^ed for 
boiling this mixture. Filter the agar-agar through a cheese 
cloth into a glass jar before it is allowed to cool and add for- 
malin in the proportion of one part of formalin to nine jmrts Ijy 
volume of the agar-agar. 
The .3 per cent solution is made in the same way as the 2 per 
cent solution, only 2.3 grams of agar-agar to .500 c. c. of distilled 
water are taken. Formalin should be added in the same manner 
and proportion as in the 2 per cent solution. Large quantities 
of the agar-agar solutions can be prepared and preserved in air 
tight vessels to prevent evaporation. 
The tissues were first put into the 2 per cent agar-agar solu- 
tion. Put a small quantity of the 2 per cent agar-agar into a 
test tube or small wide mouth bottle and place with contents 
into a vessel of boiling water until the agar-agar is melted. After 
the agar-agar is melted it should be kept at a temperature of 
70° C. The tissues are placed directly into the hot 2 per cent 
solution for two hours. Then they are transferred into the .3 
per cent solution, which has been melted in the same manner as 
the 2 per cent solution and allowed to remain for an hour or 
more. The tissues are imbedded in the .3 per cent agar-agar. 
Take a small wooden block or a plate of glass and with a camel’s 
hair brush put a layer of the hot agar-agar on one end of the 
