Sir,

I am sorry to find from your last, that you are labouring under such a weak state of health.² I sincerely trust that a little relaxation will enable you to resume with renewed vigour, those arduous and varied works from which you will be so ill spared.

I thank you for your kind attention to my queries on Passiflora &c.³ I will not trouble you now with any remarks on sterility of passion-flowers with own-pollen, further than merely stating, that I am inclined to believe—on grounds which if desirable ⁠⟨⁠I can⁠⟩⁠ communicate—you will find ⁠⟨⁠that⁠⟩⁠ —sterility—capable of a ⁠⟨⁠local⁠⟩⁠ application only. I know ⁠⟨⁠it to⁠⟩⁠ be so at least in species mentioned. Pray do not think me over-critical. I refer to it only in private, and would be the last publicly to question the validity of these long recorded statements; but being engaged in similar observations for you, I communicate them only as the results of my own practical experiments. Plants which with us may have exhibited various grades of sterility, may prove otherwise in another locality.⁴

I have now one or two singularly capricious cases of this phenomenon in species of Oncidium in store for you.⁵

I return by this evenings mail Asa Gray’s Review, for which I am greatly obliged.⁶ I may state that my observations on the capability of the rostellum for fertilisation are still entirely negative, & I have now performed not a few experiments.⁷ In my examination, however, I frequently found short tubes protruding from grains, immersed in viscous matter of rostellum, but in no case did I find these insinuating themselves into the tissues of that organ   Its viscous secretions, sufficed to generate their vital action, but its conductive prerogative seems lost; as in every case the tubes, were deflected along the anterior surface of the clinandrum towards the stigma. In Laelia I have now seen fertilisation thus accomplished, in Bletia, and Cœlogyne this was prevented by the plaister of Paris which covered the stigmas.⁸ This organ, therefore, in these genera still retains its stigmatic function, though the stylar parts are unable to accomplish theirs. I am afraid, however, since I have read Asa Gray’s observations, that I have misunderstood you, in supposing ⁠⟨⁠that the⁠⟩⁠ tubes would not only penetrate rostellum, but passing down amongst its vessels, likewise reach the ovary⁠⟨⁠.⁠⟩⁠

The capsules of Gongora atropurpurea are now swelling fast, and promise to be larger than that sent of Acropera—by the way, not a single seed has yet germinated.⁹ I am at present working on Gongora truncata which presents even greater difficulties than the former: the stigmatic chamber being all but shut. This genus, with which I suppose Acropera is now associated, is indeed a most perplexing one from your point of view.¹⁰ I will not, however encroach further at present, so with sincere wishes for a speedy recovery from your ill health,

I remain | Sir | Yours very respectfully | John Scott