Oversized monsters are never brought home either alive or preserved, and field measurements are obviously open to doubt because of the universal tendency to exaggerate dimensions. Measurements of skins are of little value; every snake hide is noticeably longer than its carcass and intentional stretching presents no difficulty to the unscrupulous explorer.

In spite of all the pitfalls, there is a certain amount of agreement on some of the giants. The anaconda proves to be the fly in the ointment, but the reason for this is not clear; the relatively wild conditions still found in tropical South America might be responsible.

There are three levels on which to treat the subject. The first is the strictly scientific, which demands concrete proof and therefore may err on the conservative side by waiting for evidence in the flesh. This approach rejects virtually all field measurements. The next level attempts to weigh varied evidence and come to a balanced, sensible conclusion; field measurements by experienced explorers are not rejected, and even reports of a less scientific nature are duly evaluated. The third level leans on a belief that a lot of smoke means some fire. The argument against this last approach is comparable to that which rejects stories about hoop snakes, about snakes that break themselves into many pieces and join up again, or even of ghosts that chase people out of graveyards; the mere piling up of testimony does not prove, to the scientific mind, the existence of hoop snakes, joint snakes, or ghosts.