3 12 
Wage ?'. — On the Structure and 
Methods. 
I have always found it necessary to make a preliminary 
investigation of the piece of stem infested by the Fungus in 
order to determine the presence of the sexual organs. Sections 
were taken here and there and examined, and, when a suitable 
region of the stem had been discovered, it was cut up into 
quite small pieces not more than about x \ to J inch long. 
Each piece was halved longitudinally, which allows the satis- 
factory penetration of the re-agent, and was then placed in the 
fixing fluid. As a fixing and hardening re-agent, I have found 
corrosive sublimate (HgCl 2 ) the most useful and successful. 
This is used in saturated solution, and the pieces of stem are 
placed in it for from one or two hours to a whole day. I have 
also used absolute alcohol and chrom. -osmium acetic acid, 
but corrosive sublimate is the most satisfactory in every way. 
The pieces of tissue are then well washed in water, trans- 
ferred to 30 c / o spirit, 50 °/ o spirit, and 70 °/ o spirit, about two 
or three hours in each, and finally transferred to 90 °/ o spirit. 
The tissues may now be stained en btoc and embedded in 
paraffin ; or they may be first embedded in paraffin and the 
sections stained on the slide. I have tried both methods, and 
found the latter the more successful, as it allows the greatest 
amount of latitude in determining the extent to which it is 
advisable to allow the stain to act, and the whole operation 
of staining and clearing can be controlled under the micro- 
scope. 
For embedding previously to staining, the tissues are trans- 
ferred to absolute alcohol for half an hour or so, then to 
a mixture of alcohol and xylol, and are finally placed in 
melted paraffin, where they remain for an hour or so. 
The sections were then cut in the ordinary way by a Cam- 
bridge rocking microtome. The ribbon was cut up into 
suitable lengths, which were mounted on the slide in the 
following way. The pieces of ribbon were first floated on 
the surface of warm water, which causes them to spread out 
perfectly flat. A piece was then floated on to a slide, the 
