No sooner was this suggestion made than naturalists all over the world began to test it, or rather to say that it ought to be tested. Some experiments have been made, but they have not been very numerous, and it can hardly be said that they entirely support Bates’s view. Sometimes they do and sometimes they do not, so as there is no reason to suppose that every butterfly is relished by every kind of insect-eating creature, this is not conclusive, till the same tests are employed in regard to butterflies that are not imitated in this way; for if the latter have not been imitated on that account, it need not be on that account that others have been imitated. Thus Belt says, as the result of his observations, “The _Heliconidæ_ are distasteful to most animals; I have seen even spiders drop them out of their webs again; and small monkeys, which are extremely fond of insects, will not eat them, as I have proved over and over again.”[108] He also “observed a pair of birds that were bringing butterflies and dragon-flies to their young, and although the _Heliconidæ_ swarmed in the neighbourhood, and are of weak flight so as to be easily caught, the birds never brought one to their nest.”[109] This seems very good evidence of the truth of Bates’s theory, but then, as against it, we learn from the same observer that “another spider that frequented flowers seemed to be fond of these very same butterflies,” and as to the spiders which were seen to drop them out of their webs, they may resolve themselves into one, since farther on Belt says, “A large species of spider also used to drop them out of its web when I put them into it.”[109] Then we are told that “there is, however, a yellow and black-banded wasp that catches them to store his nest with”; and which, having done so, “would quietly bite off its wings, roll it up into a ball, and fly off with it.”[110] Professor Poulton calls these cases “interesting exceptions,” and easily accounts for them. But might not further observation keep adding to the number of exceptions, until at last, they become so numerous that all one could say would be this: “There is a great choice of insects in tropical America, and some creatures may prefer one kind and some another, to whatever species they belong.” In India, again, where there is another family of butterflies having doubles, or understudies, only one species was refused by all the mantids which a French naturalist gave them to. Others were eaten by all of them.