Professor Häckel’s paper on the Medusæ is called ‘Beitrag zur Naturgeschichte der Hydromedusen’ (Leipzig, 1865). Professor Huxley has lent me his copy, but says he wants it returned in a week or two.² I ought certainly to have the work by me next summer, so I thought that if you happen to have it and can spare it till next autumn, I need not send to Germany for it, remembering what you said when I last saw you. I should also much like to see the other paper of Häckel’s about cutting up the ova of Medusæ.³

I have an idea that you are afraid I am neglecting Pangenesis for Medusæ. If so, I should like to assure you that such is not the case. Last year I gave more time to the former than to the latter inquiry; and although the results proved very disproportionate, this was only due to the fact that the one line of work was more difficult than the other.⁴ However, I always expected that the first year would require to be spent in breaking up the ground, and I am quite satisfied with the experience which this work has brought me. I confess, however, that but for personal reasons I should have postponed Pangenesis and worked the Medusæ right through in one year. There is a glitter about immediate results which is very alluring.