From Gustaf Retzius   3 October 1879

Dear Sir,

Last night I received your exceedingly kind invitation to come down to your house.¹ It would have been a very great honour and pleasure to me to have seen you, but hearing on my arrival here from Professor Hæckel² that you were out of health and knowing how very precious your time is for science and humanity I did not want to disturb you for a moment and do not feel it right to come now and fatigue you by a visit. I believe that the work I am now engaged in—the organ of hearing of the vertebrates, from that of the fishes to that of man—will interest you. I have been unable to get on with it as far as I hoped; I came to London to get exotic batrachians and reptiles, but I have been very unsuccessful in this. When my work once will be ready, I hope to have the honour of sending it to you or perhaps, if you will allow it then, to bring it myself.³

M^rs. Retzius⁴ joins with me in kindest regards and thanks to M^rs. Darwin.

I remain, dear Sir, | your most devoted and faithful | Gustaf Retzius