170 SUMMARY OF CURRENT RESEARCHES RELA.TING TO 



action. tSera derived from these inoculated animals do not serve to 

 differentiate the various species employed in these experiments, but 

 suggest a group relationship. Until some further refinement in these 

 procedures is devised but little reliability can be placed upon this type 

 of test as a means of identification of any culture isolated from the 

 lesions of leprosy as the bacillus of Hansen. 



Identification of the Tubercle Bacillus in Organic Fluids.* 



H. Bierry gives the following methods of concentrating tu])ercle bacilli 

 present in the body fluids : — • 



Blood. — One volume (10 to 15 c.cm.) is added to one volume of soda 

 solution (NaOH one part in 100). Make homogeneous by heating at 

 ?)5°-40" C. To one volume of the mixture add three volumes of distilled 

 water. Empty into a glass cylinder furnished with a rubber cork. Add 

 acetic acid (1 in 100), drop by drop, shaking the while. Each drop of 

 the acid causes a precipitate, which dissolves on shaking. Keep on 

 adding the acid until a slight permanent precij^itate is formed. Centri- 

 fuge ; decant the supernatant fluid, and spread the deposit on slides. 

 Add acetic acid soludon to the decanted fluid until a precipitate is 

 formed ; centrifuge afresh, ao'l make slides with the deposit as before. 

 The preparations are placed on a warm plate. V/arm each slide 

 slightly, and spread a thin film with another slide. (This is the most 

 delicate part of the operation.) The preparation takes on the appear- 

 ance of varnished glass. Fix and stain by Ziehl-Neelsen. The stain 

 should not be poured directly on the slide, but on a small rectangular 

 piece of blotting-paper placed upon the preparation. 



Pleural Exudate. — One volume of pleural exudate (10-15 cm.) i? 

 added to one volume 1/100 NaOH solution. Make homogeneous at 

 ")5°-4:0° C. Acidify and centrifuge as before. The final preparation 

 should be of the appearance of muffed glass. 



Oerehro- spinal Fluid. — Proceed as above. If the fluid contains much 

 albumen, add one volume of distilled water. 



Elastic Fibres. — The presence of elastic fibres in the expectorations 

 indicate the destruction of the pulmonary parenchyma. They are not 

 injured by the above procedure, and may be found, if present, in the 

 preparations stained with Zielil-Neelsen. 



Making Zoological Specimens Transparent.! — The method is 

 simplicity itself. Tlie organism to be preserved is treated to a 

 preliminary dehydration similar to that employed for Microscope 

 specimens followed by deflation with an air-pump. It is then 

 impregnated with and immersed in a liquid whose refractive index is 

 equal to the average index of the solid matter. The liquid is a mixture 

 of methyl-ether, salicylic acid, and benzoLbenzoate. By varying the 

 proportions of this mixture a range of refraction index is obtained quite 

 equal to that of the organisms to be embalmed. The containers are 

 rectangular jars made of a special glass of variable index, fixed in each 



* Comptes Rendus, clxiii. (1916) pp. 618-21. 



t Scientific American, through English Mechanic, civ. (1916) p. 304. 



