2 VETEEINAEY TOXICOLOGY 



these, as in most matters, far less well informed. Fiction 

 and romance have invested the malpractices of medieval 

 Italy — of such expert poisoners as the Borgias — with an 

 air of subtlety, suggesting that recondite poisons of extreme 

 violence, now no longer known, were used. There seems, 

 however, little doubt that arsenious oxide was their chief 

 agent. True subtlety and an empirical prevision of pro- 

 found pathological fact are found rather in the East and 

 among the gipsies, in the use by those peoples of vegetable 

 toxines — e.g., abrine — and dangerous moulds and fungi as 

 poisonous agents. 



The foundations of chemical toxicology were laid in the 

 earlier decades of the nineteenth century by the distin- 

 guished French physiologist Orfila. He first showed that 

 many poisons (notably arsenic) could be separated and 

 identified in the ingesta and tissues of a poisoned subject, 

 and he also did much towards elucidating the manner of 

 absorption and distribution of a poison in the system. 



Since the time of Orfila knowledge has extended, the 

 active principles of very many poisonous plants have been 

 separated and characterised, chemical methods of separation 

 of poisons from plants and from tissues have gained in 

 accuracy, and characteristic tests for many important 

 poisons have reached an extraordinary pitch of delicacy. 

 In illustration it may be remarked that arsenic can be 

 detected in such minute quantities as the five-hundredth of 

 a milligramme — i.e., the three-thousandth of a grain — and 

 recently it has been shown that hydrocyanic acid can be 

 recognised in the same small proportion. Such examples 

 render it abundantly clear that with ordinary care it is 

 impossible to fail to detect these poisons ; indeed, the 

 difficulty is often felt in the laboratory that some of our 

 tests are almost too delicate to be diagnostic of poisoning. 

 It very often indeed happens -that a substance is found 

 which, on inquiry, proves to have been given as an ordinary 

 and legitimate medicinal dose. 



