I loved the book but think the racist remark did have merit. He had the outlook shared by that time period. He described Mexican people as being as brutish as animals and stupid to risk their lives for $300 for the yellow fever experiments! Everyone else's names were used in the experiments (and given high respect) except the Mexicans who were numbered, Mexican 1,2, and 3!
The author talks about the experiments done to black people (he calls them darkies) who were of such low rank that they had no right to refuse. He repeatedly makes fun of how lazy the ex-slave Alexander is. I am a Caucasian female from the states. I think this book is definitely worth reading- I was absolutely hooked- but to deny that the racist undertone is very blind sighted!