First of all, we may note the fact that the friendly relations which dogs have become accustomed to form with men vary exceedingly in their range and activity. Perhaps in no other regard does the dog exhibit such distinctly human characteristics as in the way in which he meets the individuals of the mastering species. The gamut of their social relations with men is almost exactly parallel with our own. With from one to a dozen persons a dog may maintain an attitude of almost equally complete sympathy and mutual understanding. He may be on terms of acquaintanceship in varied degrees of familiarity with a few score others with whom he comes in frequent contact. Toward the rest of mankind he maintains a position of more or less complete distrust, which with experience may attain the indifference which men commonly show toward perfect strangers. If we observe a dog going along a much-frequented street, we may note that his relations to the people are substantially those which the folk have to each other. He shows as they do a certain consideration for the individuals he encounters, gives them their due place, and yet holds to his own. It is particularly noticeable that he avoids all contact with the other passers--in fact a dog has to be much beside himself with rage or fear, or insane from disease, before he will break those bounds of personality which civilization has set up to guide the conduct of life. [Illustration: King Charles Spaniel] The social culture of dogs appears to have gone to the point where they recognize the meaning of an introduction--at least as far as the sympathetic relations of that understanding are concerned. Almost any well-bred dog will submit to be presented by his master, or even by persons whom he knows but is not accustomed to obey, to a stranger to whom he has already exhibited some dislike. During the introduction he will submit to those formal exchanges of courtesy which he is accustomed to recognize as the indices of friendship. The impression of this understanding seems to be so permanent that on subsequent meetings the dog, though he may maintain his original dislike of the man who has been forced upon his acquaintance, will continue to treat him with a certain consideration, though it is often easy to see that it is a difficult matter for him to conform to the requirements of society. When we compare the conduct of dogs in these regards with the behavior of other animals, even highly domesticated forms, we perceive how marvellously successful has been man's unconscious effort to mould this creature on his own nature.