To the Royal Society for Prevention of Cruelty to Animals   3 May 1875

Sir

I beg leave to acknowledge the receipt of your circular of Ap. 30.¹

I am sorry to say that the state of my health renders it impossible for me to attend the meeting on May 5^th.² I regret this, as I am very anxious that some legislative measure should be passed, serving to protect animals from needless suffering, & at the same time not interfering with the progress of the science of Physiology, which I am convinced, from the analogy of all other sciences, will ultimately confer the highest benefits on mankind—³

I remain | Sir | your obedient servant | Charles Darwin.