My dear Sir

I hope that you will forgive me for troubling you, but if you are much engaged or not well, pray do not answer me, & I shall understand the reason.¹

I am very curious to learn, owing to some correspondence with Sir J. Paget on contagion, whether fairy rings start from a central point & spread outwards, or whether they commence as rings.² In this latter case what can the cause be? If they spread outwards, is any thing known of the rate of spreading?

Lastly, is it known on what the Mycelium subsists?³

Pray forgive me for being so troublesome, & believe me, with much respect | yours sincerely | Ch. Darwin