METHODS 621 



change, the locus in this case being the nervous system. We 

 are thus unable at present to give a rational explanation of the 

 efficacy of the treatment, but again attention may be directed to 

 the bearing which the development of hypersensitiveness may 

 have to the occurrence of the phenomena of infective disease, 

 and Harvey and M'Kendrick draw attention to the fact that 

 some of the concurrent symptoms associated with the treatment 

 closely resemble anaphylactic phenomena. 



■ Antirabic Serum. — In the early part of the nineteenth century 

 an Italian physician, Valli, showed that immunity against rabies 

 could be conferred by administering through the stomach pro- 

 gressively increasing doses of hydrophobic virus. Following up 

 this observation, Tizzoni and Centanni have attenuated rabic 

 virus by submitting it to peptic digestion, and have immunised 

 animals by injecting gradually increasing strengths of such virus. 

 This method is usually referred to as the Italian method of 

 immunisation. The latter workers showed from this that the 

 serum of animals thus immunised could give rise to passive 

 immunity in other animals ; and further, that if injected into 

 animals from seven to fourteen days after infection with the 

 virus, it prevented the latter from producing its fatal effects, 

 even when symptoms had begun to manifest themselves. They 

 further succeeded in producing in the sheep and the dog an 

 immunity equal to from 1-25,000 to 1-50,000 (vide p. 564), and 

 they recommended the use", in severe cases, of the serum of such 

 animals in addition to the treatment of the patient by the 

 Pasteur method. Marie obtained a similar serum by, sub- 

 cutaneous injection of the sheep with virus fixe. The use of this 

 serum to supplement the ordinary Pasteur treatment has been 

 found beneficial in severe human infections, and in ordinary 

 cases it enables the prophylactic injections of the virus to be 

 condensed. The method is now part of the routine in many 

 Pasteur Institutes. It probably prevents some of the purely 

 toxic effects of the virus in human cases. 



Methods. — (1) Diagnosis. — The work on the specificity of the Negri 

 bodies for rabies has led to a modification in the procedure to he adopted, 

 rormerly it was advisable if possible to keep an animal suspected of rabies 

 alive for the observation of symptoms. While the clinical history of the 

 animal ought to be carefully obtained, greater information will be 

 obtained by examination of its hippocampus. The animal should there- 

 fore be killed and the brain removed after reflecting the scalp and cutting 

 through the calvarium with a sharp chisel. The brain is laid down, 

 vertex uppermost, and the upper parts of one hemisphere are removed in 

 thin horizontal slices till the anterior part of the lateral ventricle is 

 reached. The roof of the ventricle is then cut away with a probe-pointed 



