"Rats and mice, for example, tend spontaneously to develop a high incidence of tumors. This renders them unsuitable for detecting tumors. Still, no animals are used as often as rats and mice for assessing the effect of numerous experimental treatments upon the production of tumors. The reason is that they are inexpensive and take up little room."
"Those experiments that cannot be justified on scientific grounds can be no more justified than the frivolous killing and torturing of animals. In fact they are even less capable of justification, since such experiments block more fruitful uses of scientific resources."
"The error in depicting critics of animal experiments as anti-science becomes clear when one begins to question the extent to which the purported scientific aims of these experiments are actually accomplished. For then it turns out that the experiments and not their critics are unscientific."
"Interspecies differences may lead to concluding that substances that are innocuous or beneficial in humans are harmful, and that substances that have insidious effects on humans are harmless. For example, penicillin is extremely poisonous to guinea pigs. Had penicillin been subjected to the routine animal tests, as new drugs presently are, it would never have been tried on humans."