THE MICROSCOPE. 207 



if they suffice at least to arrest the development of organisms in 

 liquors favorable to their multiplication. He got nothing worth 

 mentioning from the use of phenol, thymol, and salicylic acid; and,, 

 strange to say, sulphurous acid and zinc chloride also failed to de- 

 stroy all the germs of infection. The best effects were obtained 

 from chlorine, bromine, and mercuric chloride. Solutions of 

 mercuric chloride, nitrate, or sulphate when diluted i to 

 1,000 parts, destroy the fertility of the spores in ten minutes. — 

 Ex. 



Preparing Tapeworms. — Dr. G. Riehm recommends the fol- 

 lowing treatment of specimens: To prevent contraction at death, 

 he cleans the living cestode with a brush, and holds it in the hand 

 until it has extended itself under the action of the warmth, and 

 then rolls it upon a glass tube and plunges the whole into spirit; 

 undue adhesion to the glass is remedied by soaking in water. Such 

 specimens are well adapted for mounting under pressure; they may 

 be stained with alum-carmine or with haematoxylin; if with the lat- 

 ter, the specimen should be treated with acetic acid for a minute 

 after staining and then washed in ammonia to remove excess of 

 color. 



For minute investigation, sections made parallel to the flat sur- 

 faces are preferable. To prevent the last sections breaking out of 

 the imbedded mass, this* should be made of equal parts of paraffin 

 and white wax with the addition of one or two drops of Canada 

 balsam dissolved in turpentine for each gramme of the mixture. 

 The razor should be wetted with benzine, care being taken not to 

 moisten the object itself too much with the benzine. To secure 

 having the sections cut in the right place, the specimen is soaked in 

 turpentine, placed in a watch-glass of imbedding mass kept liquid 

 by heat, and left there until seen by its transparency to be thoroughly 

 penetrated; some of the mass is then removed with a hot instru- 

 ment and placed on a slide and pressed out, the specimen is placed 

 on the stage of the microtome and the slide with its paraffin is placed 

 on it; when cool the slide may be removed, leaving the specimen 

 imbedded in a strictly horizontal position. The excretory vessels- 

 are injected with Berlin blue by simple insertion of the syringe: if 

 the animal is moving actively the injection runs forward with diffi- 

 culty and in any case the neck and head require manipulating with 

 the finger or a wet brush, in order to drive the injection through, 

 the narrow portions of the vessels which occur at the joints. — Royal 

 Mic. Journal. 



