204 SOCIAL BEHAVIOUR 
first the sound seems to have the value of a simple expression 
of an emotional state. “ But if the infant require attention it 
is its mother whom it wants, and from whom it receives this 
attention ; therefore ma very soon comes to be recognized as 
the call for mother, and, by a further step in development, as 
the name for mother.” Here, if we accept the interpretation, 
we have the passage from the emission of a sound as the 
expression of emotion to the use of the sound from its associa- 
tion with a particular object of sense-experience to indicate 
that object. Similarly, according to Mr. Buckman, with kah. 
At first “a strong sign of displeasure at anything nasty to the 
taste,” it passes, we are told, into a symbol for the bad ; hence 
xaxos; and is perhaps narrowed down to the particularly 
offensive kaxxn. Da and da are regarded as recognition sounds, 
the former being associated eventually with the father, the 
latter with strangers. This appears somewhat hypothetical, 
but, granting the accuracy of Mr. Buckman’s interpretation, 
these sounds also illustrate again the transition from the 
expression of an emotion to sounds indicative of particular 
objects of experience. 
Interesting, however, as are such observations on the animal 
stage of sound-production in the human infant, they do not 
touch the crucial period in the development of language. Mr. 
Buckman, indeed, regards as a remarkably dogmatic assertion 
Professor Max Miiller’s dictum that “the one great barrier 
between the brute and man is language;” and he tells us that 
“there are more than twelve different words in the language 
of fowls,” on which assertion, in turn, the distinguished linguist 
whom he criticizes might have something piquant to say. No 
doubt the difference of opinion turns on the definition of the 
word “language.” But if, as is now generally accepted, the 
sentence and not the word is the distinguishing unit in 
language, and the copula in some form, explicit or implicit, is 
the pivot of the sentence, the wisest hen is probably incapable 
of language. The word becomes an element in language—a 
word proper—only when it assumes the office of a part of 
speech, that is to say, a constituent element in an interrelated 
