See Letter 97.) But the whole case is a mystery.
There is another point on which I have occasionally wished to say a few words.

I believe you think with Asa Gray that I have not allowed enough for the stream of variation having been guided by a higher power.

I have had lately a good deal of correspondence on this head.

Herschel, in his "Physical Geography" (130/2.

"Physical Geography of the Globe," by Sir John F.W.Herschel, Edinburgh, 1861.