236 VENOMS 



enquiries as to these Cm-ados de Gulebras, and was able to satisfy 

 himself that their immunity is an actual fact. 



The process of vaccination employed by the natives of Tuxpan 

 is as follows : — A preparatory treatment is necessary. On the very 

 day on which a man is to inoculate himself or get himself inocu- 

 lated, he takes from 5 to 15 tubers of a plant known by the name 

 of Mano de Sapo (i.e., Toad's hand, Dorstenia contrayerva, Family 

 Urticacea) . These tubers must — and this is absolutely necessary — 

 be administered on a Friday, and always in an odd number, 5, 7, 

 9, &c., up to 15, according to the tolerance of the subject. 

 ' If the plant be gathered on the first Friday in March it 

 possesses its marvellous properties in the highest degree; in this 

 case, even if it be dry, it is still excellent for the preparatory stage 

 of the inoculation. 



The physiological effects of mano de sapo are not very marked : 

 the circulation is slightly diminished and a sensation of cold is 

 experienced, but there are no nervous troubles. The subject 

 frequently has attacks of vomiting or nausea. The inclination to 

 vomit must be fought against, for if the plant should happen to 

 be rejected is would be dangerous to submit to the inoculation. 



The root of the mano de sapo is usually taken fresh. There 

 is another indispensable precaution : while undergoing this treat- 

 ment it is necessary to abstain from all sexual intercourse for 

 three days after the first inoculation, for two days after the second, 

 and for one day after the third. 



For the inoculation a large snake's tooth, that is to say, one 

 of the fangs, is employed, and the fangs of the most poisonous 

 snakes, such as the rattle-snake {cuatro narices), are selected. The 

 snake must be killed on a Friday, and the fangs extracted the 

 same day. The same fang may serve for several years ! 



The inoculation is commenced on the dorsal surface of the left 

 foot ; care must be taken to avoid coming into contact with a 

 vein. The skin is torn with the point of the fang, so that it bleeds 

 a little, and the incision is in the shape of a square. 



