VOYAGE UP THE RIO NEGRO 267 
Rio Negro, though I always had my eyes open for 
them. The following is my Cryptogamic summary 
thus far : Ferns, o ; Mosses, o ; Hepaticae, i ; 
Lichens, 3 or 4 epiphyllous species ! Would you 
have expected this of the Rio Negro ? I certainly 
hoped something better of it. In place of these 
tribes there are, however, plenty of Podostemons on 
the granite rocks which peep out of the river (and, 
by the by, make the navigation very dangerous), 
but all, all dead and burned up. It is here, as I 
remarked at Santarem, the Podostemons all flower 
just as the water leaves them, that is, early in the 
dry season ; and my ascent of the Rio Negro was 
made towards the close of the dry season ; but if I 
live, these little fellows shall not escape me. As 
their fruit is exposed to a burning sun six months 
or more in the year, I do not see why they should 
not travel safely to England in a letter, and I 
accordingly enclose capsules of one of the largest 
specimens. They ought to vegetate on stones 
(especially granite) barely einersed from the water 
of a tank ; though here they never grow in still 
water — always in rapids or cataracts where the 
water rushes over them. 
I had sad news two days ago from my friend 
Wallace. He is at Sao Joaquim, at the mouth of 
the Uaupes, a little above Sao Gabriel, and he 
writes me by another hand that he is almost at the 
point of death from a malignant fever, which has 
reduced him to such a state of weakness that he 
cannot rise from his hammock or even feed him- 
self. The person who brought me the letter told 
me that he had taken no ^nourishment for some 
days except the juice of oranges and cashews. 
