224 NOTES OF A BOTANIST 
enveloped in a sweet cottony pulp, which is very agreeable eating ; 
the Inga-sipo (of which I have already sent you the fruit) is the 
most esteemed. The Cow tree is represented on the Rio Negro 
by two Apocyneae, the Cuma-i and the Cuma-agu, both species of 
Collophora, but only one of them known to Martius. The former 
is frequent near the Barra, and early in March was a great orna- 
ment to the forest, especially near the river, being profusely clad 
with corymbose cymes of red flowers. It grows to 30 or 35 feet 
high, with a diameter of about 12 inches, and the branches and 
leaves grow in threes. The milk flows out abundantly on a slight 
incision being made in the bark ; it is of the consistency of new 
milk, of the purest white, and very sweet to the taste. The Indian 
mode is to apply the mouth directly to the gash and thus receive 
the milk as it oozes out. In this way I have many times partaken 
of it without experiencing any ill effects. Its extreme viscidity 
has suggested its employment in diarrhoea, and there is no doubt 
that if taken in sufficient quantity it would actually glue up the 
viscera. The Cuma-a^u is a much larger tree, but of similar 
habit, and the milk is of a thicker consistence ; it is said to flower 
towards the end of the year. The fruits of these two trees are 
said to be the most agreeable of any on the Rio Negro, and from 
their resemblance to the fruits of Pyrus Sorbus have been called 
Sorvas by the Portuguese settlers. 
It is perhaps among twining plants or sipbs that the greatest 
botanical novelties remain to be found ; they are in many cases so 
difficult to collect that I have no doubt a great many have been 
passed over by travellers, I am now paying particular attention 
to them, and my Barra collection includes twiners of the orders 
Leguminos?e, Connaracese, Polygaleae, Malpighiacese, Sapindaceae, 
Convolvulacese, Hippocrateaceae. 
To Dr. Semann 
Barra do Rio Negro, April 25, 185 1, 
I wish I had time to write you a long letter, but I 
am over head and ears in work, packing up rubbish 
to send to England, and I must be brief. I hope 
I have now got pretty well acclimatised here, and 
I am beginning to enjoy myself. I cannot say that 
I have ever experienced that bewilderment at the 
multitude and variety of the forms of vegetation 
