The ‘inadvertence’ (in this instance on the part of the writer who thus expressed himself) has not been without its use as well, for a more careful attention has been given to the rattle in consequence; and much controversy has since arisen among some of the ablest herpetologists, particularly in America, where much that was new and suggestive soon found its way into the scientific journals. Briefly to summarize some of the arguments, I will repeat a few of them as suggested by some well-known naturalists. In that able periodical, the _American Naturalist_, vol. vi. 1872, the subject was thoroughly discussed. Professor Shaler, in a paper on ‘The Rattlesnake and Natural Selection,’ admitted that whereas he had hitherto thought and taught that the rattle did more harm than good to its owner, he now knew that the sound is so similar to that of the stridulating insects upon which some birds feed, that he had no doubt of its use in attracting these to the snake. He himself had mistaken the sound for a locust. ‘Does it invite its enemies or entice its prey?’ he asks. ‘Those snakes that can best attract birds, are best fed.’ In reply to this, a Mr. J. W. Beal of Michigan affirmed that he had often mistaken the sound for grasshoppers; which educed many similar accounts from persons who had been in danger of treading on a Crotalus through ‘inadvertent approach,’ supposing that only an insect were there. A child had taken it for a cicada, some one else for a locust, etc. Any one who is acquainted with the wild parts of the American Continent, is familiar with the ceaseless chirps and whizzings of those ubiquitous insects which are furnished with the stridulating apparatus, and which lead you almost to expect to see a scissors-grinder behind every tree. These are all the more deceptive on account of their varying cadences, now louder, now softer, approaching or receding, just as the sound of the rattle varies by increased or less rapid vibrations, or according to its individual size and strength. In a paper read before the Zoological Society by Mr. A. R. Wallace in 1871, he invited attention to this fact of the resemblance between the sound of the rattle and the singing of a cricket, and that its use seemed to be to decoy insectivorous animals. Dr. Elliott Coues is also of this opinion, viz. that to an unpractised ear the sound cannot be distinguished from the crepitation of the large Western grasshopper. A case has been reported, he tells us, of a bird observed to be drawn within reach, thinking it was a grasshopper. Dr. Coues also affirms that the sound has been heard when no perceptible irritation disturbed the snake.[87] Thus we see that the ‘inadvertent intruder,’ so far from being warned away, is beguiled to his injury, both in the case of human beings not quick to discriminate sounds, or not having rattlesnakes in their minds, and with animals in their early experience who perhaps hear one for the first time.