I have been absent on a journey to Dublin and elsewhere [Visiting Sir Philip Egerton at Oulton Park.] nearly all this week, and hence your note and proof did not reach me till yesterday. I have but just had time to glance through the latter, and I need hardly say how heartily I concur in its general tenor. I have, however, marked one or two passages which I think require some qualification. Then, at page 272, the fact that the vital manifestations of plants depend as entirely as those of animals upon the fall towards stable equilibrium of the elements of a complex protein compound is not sufficiently prominent. It is not so much that plants are deoxidisers and animals oxidisers, as that plants are manufacturers and animals consumers. It is true that plants manufacture a good deal of non-nitrogenous produce in proportion to the nitrogenous, but it is the latter which is chiefly useful to the animal consumer and not the former. This point is a very important one, which I have never seen clearly and distinctly put--the prettiness of Dumas' circulation of the elements having seduced everybody. Of course this in no way affects the principle of what you say. The statements which I have marked at page 276 and 278 should have their authorities given, I think. I should hardly like to commit myself to them absolutely. You will, if my memory does not mislead me, find authority for my note at page 283 in Stephenson's life. I think old George Stephenson brought out his views at breakfast at Sir R. Peel's when Buckland was there. These are all the points that strike me, and I do not keep your proof any longer (I send it by the same post as this note), because I fear you may be inconvenienced by the delay. Tyndall is unfortunately gone to Switzerland, so that I cannot get you his comments. Whether he might have picked holes in any detail or not I do not know, but I know his opinions sufficiently well to make sure in his agreement with the general argument. In fact a favourite problem of his is--Given the molecular forces in a mutton chop, deduce Hamlet or Faust therefrom. He is confident that the Physics of the Future will solve this easily. I am grieved to hear such a poor account of your health; I believe you will have to come at last to the heroic remedy of matrimony, and if "gynopathy" were a mode of treatment that could be left off if it did not suit the constitution, I should decidedly recommend it. But it's worse than opium-eating--once begun and you must go on, and so, though I ascribe my own good condition mainly to the care my wife takes of me, I dare not recommend it to you, lest perchance you should get hold of the wrong medicine. Beyond spending a night awake now and then I am in very good order, and I am going to spend my vacation in a spasmodic effort to lick the "Manual" into shape and work off some other arrears.