ARNOLD ARBORETUM,HARVARD UNIVERSITY.Jamaica Plain, Mass,...........April 3,............... 1890.My dear Muir:I have yours of the 28th with photograph of Picea engelmarmi in the Bitterroot Reservation. The picture is a lovely one and, ifit will answer for the purpose, I will have a transparency made from it. Will let you know in a few days what luck I have in this. I still want the Redwood and Sugar Pine, hut these are difficult fellows to manage, for the bigger the tree the harder It is to photograph it well.I return Mr. Sawyer\u27s letter and enclose the notice about The Silva from The Evening,Post and Nation. Like most people who write about the book, this writer devotes more attention to the question of nomenclature than to the true inwa...