and Laboratory Methods. 2721 



GENERAL LABORATORY TECHNIQUE. 



RAYMOND PEARL, University of Michigan. 



Books and Papers for Review should be Sent to Raymond Pearl, Zoological Laboratory, 

 University of Michigan, Ann Arbor, Mich. 



Sealing Mixtures for Bottles and Prepa= In a recent number of the Pharma- 

 ration Jars. ceutical Era (Vol. XXX, p. 528, 1903), 



the following formulae for " bottle capping " mixtures are given. It is probable 

 that they will prove useful in general laboratory practice : 



I. Put a weighed amount of dry glue or gelatin in water and let it stand 

 over night. In the morning drain and press off the superflous water, and then 

 dissolve the swollen mass by heating in a water bath. Add one-half as much 

 glycerine as there is liquid gelatin and for every ounce of gelatin add 1 ounce 

 of tannic acid. Stir until the mass is entirely homogeneous. Mineral colors 

 may be used in case it is desired to color the sealing mixture. The mixture 

 should be tested on glass before using. If, when dry, it is too hard or brittle 

 add a little more glycerine, if too soft, add more glue and tannin, preserving the 

 proportion between them indicated above. 



II. Shellac, ------ 3 ounces 



Venice turpentine, - - - - 1^ ounces 



Boric acid, ------ 72 grains 



Powdered talcum, - - . - 3 ounces 



Ether, - - 6 fi. drams 



Alcohol, - 121^ fl. drams 



Dissolve shellac, turpentine and boric acid in the mixed alcohol and ether. 

 Color with some spirit soluble dye, and add the talcum. During use the mixture 

 must be frequently agitated. 



III. Collodion varnish, 



Pyroxylin, ------ 1 ounce 



Ether, - - - . - . 6 ounces 



Alcohol 8 ounces 



Dissolve and add camphor, 2}4 drams. Aniline dyes may be used for color- 

 ing. When used the cork and part of the neck of the bottle should be dipped 

 in the fluid. R- i'- 



The Demonstration of Nucleated Red Under this title Dr. E. T. Williams 

 Blood Corpuscles in Animal Spleens. describes in Amer. Med., Vol. VI, pp. 



855-856, his technique for fixing and staining erythroblasts. He finds it neces- 

 sary in the first instance to have absolutely fresh material. He does not use 

 spleens which have been kept more than six hours after death. The spleen of 

 the hog is a suitable object. " The first step is the preparation of the slide. 

 Take a fresh spleen, wash it carefully, and cut from the outer edge with a clean, 

 sharp knife or razor, a wedge-shaped piece, like a piece of pie, about two inches 

 long. Take it by the broad end between the thumb and forefinger and draw 

 the raw point across the middle of a clean glass slide, without pressing or 



