I have started to notice out of his test groups that about 3 out of 20 monkeys have no reaction whatsoever to tryptamines and phenethylamine. no pyschedelic effects whatsoever. the monkeys that seem to be immune are uneffected by phenethylamine and tryptamines alike. is there any explanation for this such as an altered brain chemistry, lack of neurotransmitter site etc. or no that i think about it im going to check the medications the monkeys are on to see if i can find further insight into this.