14063
In it , the author addresses the ancient history of venom and immunity , from the Silurian Era to the 1890s ; the development of the first antivenoms ; the impact of shifting political and economic pressures ; the special case of Arizona ; the relative stability of the 1960s through 1990s ; the transition to regulatory compliance that took place at the time of the author ' s own research ; and concluding thoughts regarding the instability of apparent success .
 None
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 None