From J. S. Burdon Sanderson   26 June [1874]¹

My dear M^r Darwin,

Again I have to apologize for delay. I am on the point of starting on a short tour in Germany and have been much pressed during the last few days in making preparations for my absence.

I am delighted to learn that Pinguicula & Drosera both digest fibrin readily   I do not think it would be correct to infer that the fibrin previously used was impure—but rather that it had undergone change to a certain extent consequent on the way in which it was prepared.²

I think that it would be fairest & best to experiment on gluten already subjected to the action of very dilute Hydrochloric acid ($\frac{1}{2}$ per cent)   It would thus be deprived entirely of its starch, which would be dissolved out in the form of Dextrine³   I have ask my assistant M^r. Page⁴ to send you some already so treated   He will send at the same time some bone treated in the same way. I have no doubt that the reason that the other did not digest completely was that the acid was insufficient to dissolve out the inorganic constituents of the bone

I mentioned in my last that I had put some enamel to digest. It was nearly digested by next morning.⁵

I am very sorry that I made a misstatement about the “aggregation”⁶ I said so little about it & expressed myself so indefinitely that I hope that no one would be seriously misled. I felt that I was dealing with a matter about which I had no adequate knowledge.

I hope that it may be possible to do something with Pinguicula about separating the digestive ferment. I should like very much to try after my return.

I am, my dear M^r Darwin | very sincerely yours | J B Sanderson