The growth of the lama is very quick, and its life is but of short duration. This animal couples at three years of age, and remains strong and vigorous till twelve, after which it begins to decline, and becomes entirely useless at fifteen.[AK] Their nature appears to be modelled on that of the Americans; they are gentle and phlegmatic, and do every thing with the greatest leisure and caution. When they stop on their journeys to rest, they bend their knees very cautiously, in order to lower their bodies without disordering their load; and as soon as they hear their driver whistle, they rise up again with the same precaution, and proceed on their journey. They feed as they go along, whenever they can find grass; but they never eat in the night, even though they have fasted all day; they employ that time to ruminate. When they sleep or ruminate, they rest with their feet folded under their bellies. When overloaded, or fatigued, they sink down, and will not rise again though the driver strikes him with his utmost force. His last resource to urge them forward by means of anguish, is to compress their testicles; this often is of no effect, and if the driver continues his torments the animal grows desperate, and kills himself by violently beating his head against the earth: they do not make any defence either with their feet or teeth, and it may be said, they have no other arms than those of indignation. When persecuted they spit in the face of those who oppress them; and the Indians say, that this saliva is of such an acrimonious nature, as to cause very dangerous eruptions on the skin. [AK] At Chili, according to Molina, they consider thirty years as the ordinary term of the life of a lama; and it is certain that these animals begin to propagate at the age of three years.