118 BIOLOGY AND TECHNIQUE . 



WADSWORTH'S METHOD. 11 Wadsworth has devised a method of staining 

 capsules which depends upon the fixation of smears with formalin. After 

 such fixation capsules may be demonstrated both with simple stains and by 

 Gram's method. The technique is as follows: 



Smear preparations, made as usual, are treated as follows: 



1. Formalin, 40 per cent, two to five minutes. 



2. Wash in water, five seconds. 



SIMPLE STAIN. DIFFERENTIAL STAIN (Gram's Method). 



3. Ten per cent aqueuos gentian-violet. 3. Anilin gentian-violet, two minutes. 



4. Wash water, five seconds. 4. lodin 'solution, two minutes. 



5. Dry, mount in balsam. 5. Alcohol, 95 per cent, decolorize. 



6. Fuchsin, dilute aqueous solution. 



7. Wash water, two seconds. 



8. Dry, mount in balsam. 



It is important that the formalin be fresh and the exposure to water 

 momentary. When decolorizing in the Gram method, strong alcohol only 

 should be used. Wadsworth also found that encapsulated pneumococci could 

 be demonstrated in celloidin sections of pneumonic lesions hardened in strong 

 formalin. The lungs should be distended with the formalin or the lesions 

 cut in very thin bits, hardened, dehydrated, embedded, and cut in the usual 

 way. The celloidin sections may be fixed on the slides by partially dis- 

 solving the celloidin in alcohol and ether and setting the celloidin quickly 

 in water before staining. Failure to obtain pneumococci encapsulated in 

 such sections is usually due to improper or inadequate fixation in the formalin. 



The differential method employed by Wadsworth for tissue staining is 

 as follows: 



1. Fix in formalin forty per cent, two to five minutes. 



2. Wash in water. 



3. Anilin gentian-violet, two minutes. 



4. lodin solution, two minutes. 



5. Alcohol, ninety-five per cent, decolorize. 

 6. Eosin alcohol, counterstain. 



7. Clear in oil of origanum. 



8. Mount in balsam. 



Flagella Stains. All flagella stains, in order to be successful, necessitate 

 particularly clean cover-slip preparations, best made from young agar cul- 

 tures emulsified in sterile salt solution. Scrupulous care should be exercised 

 in cleaning the glassware used. 



11 Wadsworth, Jour. Inf. Dis., 1906. 



