30 The Naturalist in Nicaragua 
to the milk, in the proportion of one pint to a gallon, coagu- 
lates it to rubber, which is made into round flat cakes. A 
large tree, five feet in diameter, will yield when first cut about 
twenty gallons of milk, each gallon of which makes two and 
a half pounds of rubber. I was told that the tree recovers 
from the wounds and may be cut again after the lapse of a 
few months; but several that I saw were killed through the 
large Harlequin beetle (Acrocinus longimanus) laying its eggs 
in the cuts, and the grubs that are hatched boring great holes 
all through the trunk. When these grubs are at work you 
can hear their rasping by standing at the bottom of the tree, 
and the wood-dust thrown out of their burrows accumulates 
in heaps on the ground below. The government attempts 
no supervision of the forests: any one may cut the trees, and 
great destruction is going on amongst them through the 
young ones being tapped as well as the full-grown ones. The 
tree grows very quickly, and plantations of it might easily 
be made, which would in the course of ten or twelve years 
become highly remunerative. 
We left Castillo at daylight the next morning, and con- 
tinued our journey up the river. Its banks presented but 
little change. We saw many tall graceful palms and tree 
ferns, but most of the trees were dicotyledons. Amongst 
these the mahogany (Swzetonia mahogani) and the cedar 
{Cedrela odorata) are now rare near the river, but a few such 
trees were pointed out to me. High up in one tree, under- 
neath which we passed, were seated some of the black Congo 
monkeys (Mycetes palliatus) which at times, especially before 
rain and at nightfall, make a fearful howling, though not so 
loud as the Brazilian species. Screaming macaws, in their 
gorgeous livery of blue, yellow, and scarlet, occasionally flew 
overhead, and tanagers and toucans were not uncommon. 
Twelve miles above Castillo we reached the mouth of the 
Savallo, and stayed at a house there to breakfast, the owner, 
a German, giving us roast wari, fowls, and eggs. He told me 
that there was a hot spring up the Savallo, but I had not time 
to go and see it. Above Savallo the San Juan is deep and 
sluggish, the banks low and swampy. The large palm, so 
common in the delta of the river, here reappeared with its 
great coarse leaves twenty feet in length, springing from near 
the ground. 
