Microscopical Diagnosis. 487 



Nelis, especially in Gl. nodosum, in Gl. cervicale supremum, and in 

 Gl. Gasseri (see p. .472), which are only eonspicuous when the animals 

 have died from street rabies, merely justify a diagnosis of suspected rabies, 

 because, according to investigations by Bohl, McCarthy & Ravenel, 

 Frothingham, and others, they are also present in other infectious 

 diseases. Besides, according to Manquelian and Vallee, the ganglia of 

 old dogs show a similar microscopic picture ; Raymond, however, found 

 that both in nervous distemper and in healthy old dogs the small cellular 

 infiltration was considerably less pronounced, while the nerve cells 

 showed normal nuclei and no migratory round cells were contained in 

 the perivascular spaces. Therefore, this method may still render good 

 service, particularly in cases where suspicion of rabies already exists, 

 and when the detection of Negri bodies is not successful. 



The examination always requires the preparation of regularly stained sections, • 

 but may be finished in 12 to 24 hours by means of the aceton-paraffin imbedding 

 method. 



Diagnostic Inoculations. If material from the animal is successful 

 in producing rabies artificially in another animal,' there caii be no 

 doubt that the former was infected with rabies. For inoculation pur- 

 poses the medulla oblongata of the suspected animal is most suitable, 

 from the center of which a small piece is excised with sterilized instru- 

 ments, carefully rubbed into an emulsion with boiled water and then 

 filtered through clean, fine, linen cloth. For test animals rabbits and 

 dogs are most suitable, but guinea pigs (Konradi), mice and rats 

 (Fermi) may also be used. 



The subdural injection (Pasteur) is performed in rabbits by trephining one 

 of the parietal bones of the animal with a small trepan (diameter 5-6 mm.), and 

 then 1-2 drops of the previously prepared emulsion is injected between the dura 

 and the surface of the brain by means of a hypodermic needle which is bent in 

 a right angle. The opening is then covered with the skin, and the edges of the 

 wound are united by means of sutures. 



For the intracerebral injection (Leclainche), a small opening is made in 

 the cranium by means of a fine drill, and %-% ce. of the above named emulsion 

 is injected about 1 cm. deep into the brain with a straight needle. 



The intraocular injection (Gibier, Nocard, Johne) recommends itself owing 

 to its simplicity. The cornea which previously has been anesthetized by the 

 application of cocaine (10-20 drops of a 2-5% solution), or acoin (0.1% solution), 

 is perforated with the straight needle, and 1-2 drops of the emulsion is injected 

 into the anterior ocular chamber. 



In the intramuscular injection which also has stood the test (Helman, 

 Klimmer), 1.0 cc. of the emulsion is injected into the muscles of the legs or 

 shoulders of a rabbit or guinea pig. This method is particularly to be preferred 

 in cases where the brain substance is not fresh, or the purity of the injection material 

 is questionable for some reason or other. 



For the same purpose Lebell recommends the injection under the meninges 

 of the spinal cord; Galli-Valerio mentions the injection into the cranial cavity 

 through the foramen occipitale magnum, or rubbing the infected material into the 

 mucous membrane of the nose by means of a piece of cotton fastened to a wire 

 (according to Konridi, the period of incubation in this case is sometimes very long). 

 Dawson and Oshida recommend an injection in the cranial cavity through the 

 foraipen opticum (inserted beside the inner angle of the eye, along the wall of 

 the ocular cavity) ; finally Szpilmann recommends the injection under the conjunctiva 

 (Hogyes, however, found this proceeding mostly^ ineffective). The subcutaneous 

 and the intravenous injections are very unreliable, and therefore they are not to 

 be recommended. It is also advisable to inject at least 2 animals by the above 

 mentioned methods, because sometimes the injection of the same virulent material 

 does not affect every animal. 



The methods just described are easy to adopt in general veterinary practice, 

 owing to their simplicity; if, however, the laboratory of an institution has been 

 secured for this purpose, the test material must be sent there in a condition fit for 



