MICROSCOPICAL TECHNIQUE. 95 



Examination of Sputum for Tubercle Bacillus.— Spengler 

 [Deutsch. Med. Woch., 1895, No. 15) describes a new method for 

 the preparation of sputum, wliich it is desired to investigate for 

 the presence of tubercle bacilH. Equal volumes of sputum and 

 of warm water rendered feebly alkaline with caustic soda are well 

 mixed with o"i to i"o per cent, of trypsin and placed in the incu- 

 bator. Putrefaction is prevented by the addition, two or three 

 hours later, of a small quantity of crystalline carbolic acid. As 

 soon as a deposit has formed, the supernatant fluid is poured off, 

 the deposit was had with pure alkaline water and again placed in 

 the incubator. This process is repeated several times, and finally 

 the sediment is collected upon a filter paper and dried somewhat. 

 Portions are then stained in the usual way. As a rule, in twelve 

 to twenty-four hours, so little sediment remains that only a few 

 microscopic slides are needed. If the digestion of the sputum be 

 not carried on for too long a time, the tubercle bacilli undergo no 

 modification in their staining properties. — Brit. Med. Journal. 



Rapid Staining.— Cullen {Ce/itr. f. allge. Path. 11. Patholog. 

 Anai., 1895, Bd. VI., No. II., p. 448) describes a rapid method 

 for staining fresh tissues after hardening with formalin. Sections 

 can be stained in the post-mortem room within fifteen minutes of 

 removal of the tissue from the body. The fresh material is frozen, 

 and sections are cut and placed in 50 per cent, watery solution of 

 formalin for five minutes, thence into 50 per cent, alcohol (one 

 minute), and washed in water; they may then be stained and 

 mounted in the usual way. Another method by which better 

 results are obtained takes two hours and a quarter. In it the 

 fresh material is soaked in a 10 per cent, watery solution of for- 

 malin for two hours, and then frozen, cut, and placed in 50 per 

 cent, alcohol, The later procedure is as in the previous method. 

 The pieces of tissue in the second method must not be greater 

 than two millimetres in thickness. — Brit. Med. Jour uaL 



Staining the Wings of Insects.— In No. 4 of Vol. I. of the 

 Biological Review of Ontario, Dr. H. W. Hill gives the following 

 method, devised at the request of Dr. Brodie, of staining the 

 veins in the wings of certain insects : — 



Place the whole insect in a strong alcoholic solution of fuch- 

 sin and allow it to remain there for forty-eight hours. Then 



