86 SUMMARY OF CURRENT RESEARCHES RELATING TO 



good results. Small pieces are placed for twenty-four hours in a mixture 

 of 7 parts of 1 p.c. chromic acid, 7 parts of 3 p.c. potassium bichromate, 

 and 4 parts of 2 p.c. osmic acid. After removal they are washed in 

 distilled water and then placed in a mixture of 1 part acid acet. pyrolig- 

 nosum rect. and two parts of 1 p.c. chromic acid. After twenty-four 

 hours they are washed for half an hour in distilled water, and then placed 

 for three days in 3 p.c. bichromate of potassium. They are then washed 

 in running water and afterwards embedded. The preparations are then 

 treated in the following manner : — 1. Stain, heating to vaporization, 

 with Altmann's acid-fuchsin (20 grm. acid-fuchsin in loo c.cm. anilin 

 water). 2. Wash with distilled water. 3. Stain for 1 to 2 minutes in 

 a saturated aqueous solution of thionin, or in a ' 5 p.c. aqueous solution 

 of toluidin blue. 4. Wash in distilled water. 5. Differentiate with 

 0*5 p.c. solution of aurantia in 70 p.c. alcohol (20 to 40 seconds con- 

 trolling under the Microscope). 6. Dehydrate in % p.c. alcohol, 

 7 absolute alcohol, 8 xylol of balsam. 



The balsam used by the author is Merck's glass-hard balsam dissolved 

 in pure benzol. Preparations mounted in this medium have kept 

 unchanged, while controls mounted in other varieties of balsam have 

 materially deteriorated. 



Diagnosis of Rabies.* — Lena Xegri Luzzani gives the technique by 

 which the specific parasite of rabies may be demonstrated. She first 

 describes the procedure for opening the skull and removing that portion 

 of the brain known as the cornu ammonis. A minute portion of the 

 nervous substance is placed on a slide and teased out with very dilute 

 acetic acid. In this way a fair number of nerve cells may be isolated 

 and the intracellular parasite detected. AVhen it is not possible to carry 

 out the foregoing technique at once, or if the examination has been 

 negative, it is advisable to immerse small pieces of the cornu ammonis in 

 Zenker's fluid : Bichromate of potassium, 2*5; corrosive sublimate, 5 ; 

 water, 100 ; adding before use acetic acid 5. The small pieces are 

 sufficiently fixed in from two to four hours, and then they are washed in 

 water for a few minutes. Very little bits are then teased out on a slide 

 and examined as before. It is easier to find the parasite after fixation 

 by Zenker than in the fresh material. In certain cases it is necessary to 

 investigate by means of sections. Paraffin sections are made in the 

 usual way and then stained by Mann's method. The staining solution 

 consists of aqueous solution of eosin, 1 p.c. 45 c.cm. ; aqueous solution of 

 methylen-blue, 1 p.c. 35 c.cm. ; distilled water 100 c.cm. The eosin and 

 methylen-blue solutions are to be mixed when required for use. The 

 sections remain in the stain for about half an hour, and on removal are 

 immersed in absolute alcohol for several minutes. When dehydrated 

 they are differentiated in alkaline alcohol (absolute alcohol, 30 c.cm. ; 

 caustic soda dissolved in absolute alcohol, 5 drops). Differentiation is 

 continued until the sections lose the blue and become quite red. After 

 a rapid wash in absolute alcohol the sections are plunged in tap-water, 

 and then in distilled water acidulated with acetic acid. In the last bath 



* Aim. Inst. Pasteur, xxvii. (1913) pp. 1039-62 (1 pi. and 3 figs.). 



