194 
METHODS IN PLANT HISTOLOGY 
plant. The young stages are likely to be overlooked and even when 
noticed are likely to be lost if you attempt to remove Coleochaete 
from its host. If you think you must remove it from the host, 
complete the staining before the removal. 
Fix in the special chromo-acetic-osmic solution and stain sharply 
in Delafield’s haematoxylin. If you overstain and reduce with 
hydrochloric acid (3 or 4 drops in 100 c.c. of water), the Coleochaete 
will stand out against the host, which is not likely to stain so deeply 
as the alga. A slight tinge with orange in clove oil may increase the 
contrast between the alga and its host. 
After staining, the material may be run up through a series of 
alcohols, 5, 10, 20, 35, 50, 70, 85, 95, and 100 per cent, about 15 
minutes in each grade. If orange in clove oil is used, apply it here 
and transfer to xylol. Mount in balsam. If no orange is used, 
transfer to 25, 50, 75, and 100 per cent xylol, and mount in balsam. 
After staining, the Venetian turpentine method may be used instead 
of the rather long series of reagents. 
Sections are easily cut and, especially in forms with a flat thallus, 
show features which might escape if one depended entirely upon 
plants mounted whole. Cut out small pieces of leaf or stem 
abundantly covered with Coleochaete , imbed in paraffin, and cut 
host and guest together. 
Chara.— Chara is found in ponds, lagoons, and ditches. Once 
seen, it is always readily recognized. In the ponds and lagoons 
along the southern shores of Lake Michigan it fruits so abundantly 
that the whole pond shows an orange color due to the immense 
numbers of antheridia. In the lagoons of the Chicago parks Chara 
is so abundant that it must be dredged out every summer. 
Chara is easily kept alive throughout the year in the laboratory. 
A 2-gallon glass jar with an inch of pond dirt, sand, and gravel at 
the bottom, and nearly filled with tap water, is all that is needed for 
a successful culture. If the jar is to be covered, it should not be 
more than two-thirds full of water. Not more than a dozen plants 
should be put into such a jar. 
A rather strong solution should be used for fixing. The following 
will give good results: 
Chromic acid . 1 g. 
Glacial acetic acid. lc.c. 
Water. .. 100 c.c. 
