Without stopping to refute in detail all the reasons which he has advanced to support his opinion, we cannot help saying something of them; and in the first place, the difference of size uniformly exists; it is evident that it does not arise from great exercise, since it is found in the infant at birth, and the nourishing artery of the right arm is larger than that of the left. If the right arm be not really stronger than the other, why should we always use it in preference? If we employ it in writing, should we say with Bichat, that it is only because it is better situated to move from left to right, in the order in which the characters of our writing succeed each other; might it not be said, with more reason, that our letters go from left to right, because it is the direction in which the right hand most easily traces them? All this besides relates merely to the form of our characters, since all the oriental languages are written from right to left; yet it is always done with the right hand. Is it still said that the necessity of union in battle has led to the employment of the right arm to hold the weapons, as if the Hurons or Algonquins fought in close ranks like our Grenadiers. If this use of the same arm or the same leg was only conventional, why among some people, is the left side never preferred? [12] The theory of wind instruments is not yet sufficiently well understood, to enable us to say, what sort of influence would be exerted upon the sound by the inequality of vibrating plates. (See the article Voice, in my Elements of Physiology, Vol. 2d.) CHAPTER IV. GENERAL DIFFERENCES OF THE TWO LIVES WITH RESPECT TO DURATION OF ACTION. One of the great distinguishing characters of the phenomena of the animal life in opposition to those of the organic life, has just been shewn. That, which I am about to examine, is not of less importance. The functions of the animal life intermit; the functions of the organic life are performed with an uninterrupted continuity. I. _Of continuity of action in the organic life._ Prolong but little the causes which are capable of suspending respiration, or the circulation of the blood, and life itself shall be suspended, nay, even annihilated. All the secretions go on uninterruptedly; if they intermit at all (and those of the bile and saliva for instance, when not immediately required for the purposes of digestion and mastication, may be said to intermit) such intermissions affect the intensity of the secretion only, and not the entire exercise of the function. Exhalation and absorption incessantly succeed each other; the process of nutrition must be continually carried on; the double movement of assimilation and decomposition from which it results, can only be terminated with life itself.