172 THE MICROSCOPICAL NEWS. 
Dr. Morris method.—F¥irst gently warm the slide, centre it on 
the turntable, warm the cover glass, and place it on the slide, wash, 
the pipette with a little carbon bisulphide, take up a small quantity 
of the solution of phosphorus, and allow it to run under the cover 
just to float it. Take asmall brush, load it with the melted 
cement, and touch the edge of the cover glass in four places, gently 
revolve the turntable, keeping the brush close to the cover until 
the cement ring is complete, then absorb the remainder of the 
phosphorus solution with strips of blotting paper, putting the 
paper in water so that it may not inflame. After a day’s rest the 
slides may be examined, and, if perfect, finished with a ring of 
sealing wax or shellac. 
Precautions to be taken.—Both phosphorus and bisulphide of, 
carbon are extremely inflammable substances, and require to be 
used with the utmost caution. Burns resulting from accidents with 
phosphorus are usually very severe. All paper and textile sub- 
stances brought into contact with the solution of phosphorus in 
bisulphide of carbon should be put into water at once to be burned 
or cleansed at leisure. If spilled on the hands it should be 
removed zzstantly with olive oil. The operator can hardly be too 
careful in handling the solution, and even after the slide is mounted 
there is danger. Mr. Frank Crisp, at the meeting at which Dr. 
Morris described his process, said, ‘‘ It must be borne in mind 
that the danger incidental to the use of phosphorus was not con- 
fined to the process of mounting. A case recently occurred, in 
which an object glass brought down too hard, broke the cover 
glass, and the observer having wiped off the exuding phosphorus 
with his handkerchief put it into his pocket, and set himself on 
fire. 
PENETRATION IN OBJECTIVES. 
YHERE are yet many microscopists who consider “ the battle of 
the glasses” not fought out, and who still look upon the 
various statements made from time to time upon the “ penetration ” 
of objectives as so many theoretical speculations not proved by 
practice. 
It is to these we now address ourselves, and knowing that 
mathematical problems are not cared for generally by the majority 
of microscopists, put the matter in a practical form in order to win 
the sympathies of those with whom hypotheses, of whatever kind, 
are subordinated to what can be seen “ over the tube.” Professor 
Abbe has demonstrated, in a very clear manner, how penetration 
