I am quite touched by your story about the illegal market for tiger parts, mainly in China, where they are highly valued for their medicinal potency (“Market Failure,” April 21, 2007). To the best of my knowledge, the most highly valued tiger part is its penis, which is believed to increase male potency. According to your sources, there are about 5,000 tigers bred for parts on illegal Chinese farms, and about 2,500 adult tigers left in the wild, mainly in India. And so I went through a little bit of arithmetic. Assuming that there are 1.3 billion Chinese, that one Chinese in a thousand would go for such a potency medicine, and that one half of the 7,500 tigers are male, this would amount to 400,000 customers per tiger penis—no matter how many customers a single penis can serve. Ouch. The mother of all market failures.