For it must be remembered, as I am afraid I have already perhaps too often said, that even when we have got a slight variation of instinct, due to some cause which we know nothing about, but which I will not even for a moment call “spontaneous”—a word that should be cut out of every dictionary, or in some way branded as perhaps the most misleading in the language—we cannot see how it comes to be repeated in successive generations, so as to be capable of being acted upon by “natural selection” and accumulated, unless it be also capable of being remembered by the offspring of the varying creature. It may be answered that we cannot know anything about this, but that “like father like son” is an ultimate fact in nature. I can only answer that I never observe any “like father like son” without the son’s both having had every opportunity of remembering, and showing every symptom of having remembered, in which case I decline to go further than memory (whatever memory may be) as the cause of the phenomenon. But besides inheritance, teaching must be admitted as a means of at any rate modifying an instinct. We observe this in our own case; and we know that animals have great powers of communicating their ideas to one another, though their manner of doing this is as incomprehensible by us as a plant’s knowledge of chemistry, or the manner in which an amœba makes its test, or a spider its web, without having gone through a long course of mathematics. I think most readers will allow that our early training and the theological systems of the last eighteen hundred years are likely to have made us involuntarily under-estimate the powers of animals low in the scale of life, both as regards intelligence and the power of communicating their ideas to one another; but even now we admit that ants have great powers in this respect. A habit, however, which is taught to the young or each successive generation, by older members of the community who have themselves received it by instruction, should surely rank as an inherited habit, and be considered as due to memory, though personal teaching be necessary to complete the inheritance.