81 



SCIENTIFIC SIDE-LIGHTS 



Bod 



Body 

 Brain 



complish no design, except through knowl- 

 edge and through use of the appropriate 

 and appointed means. Nor can those means 

 be ascertained except by careful observa- 

 tion, and as careful reasoning. It is a hard 

 thing to know all the forces which operate 

 even on our own individual minds; and it 

 is a much harder problem to understand the 

 forces which arise out of the complicated 

 conditions of human society. ARGYLL 

 Reign of Law, ch. 7, p. 197. (Burt.) 



395. BOW, THE, A PREHISTORIC 

 WEAPON Stone Arrow-heads Prove Antiquity. 

 However invented, the bow came into use 

 in ages before history. Its arrow is a mini- 

 ature of the full-sized javelin, and the old 

 stone arrows-heads found in most regions of 

 the world show the existence of the bow 

 and arrow in the Stone Age, tho hardly back 

 to the drift period. The art of feathering 

 the arrow goes back as far as history, and 

 we know not how much further. TYLOR 

 Anthropology, ch. 8, p. 195. (A., 1899.) 



396. BRAIN, ACTIVITY OF, PRODU- 

 CES LOCAL HEAT Anger Really a Hot Pas- 

 sion Great Strain of Silent Recitation. 

 Brain-activity seems accompanied by a local 

 disengagement of heat. . . . Dr. J. S. 

 Lombard . . . found [in more than 

 60,000 observations] that any intellectual 

 effort, such as computing, composing, recit- 

 ing poetry silently or aloud, and especially 

 that emotional excitement such as an anger 

 fit, caused a general rise of temperature, 

 which rarely exceeded a degree Fahrenheit. 

 The rise was in most cases more marked in 

 the middle region of the head than else- 

 where. Strange to say, it was greater in 

 reciting poetry silently than in reciting it 

 aloud. Dr. Lombard's explanation is that 

 " in internal recitation an additional por- 

 tion of energy, which in recitation aloud 

 was converted into nervous and muscular 

 force, now appears as heat." I should sug- 

 gest rather, if we must have a theory, that 

 the surplus of heat in recitation to one- 

 self is due to inhibitory processes which are 

 absent when we recite aloud. . . . The 

 simple central process is to speak when we 

 think; to think silently involves a check in 

 addition. JAMES Psychology, vol. i, ch. 3, 

 p. 99. (H. H. & Co., 1899.) 



397. BRAIN BENUMBED BY HEAT 



Effect of Molecular Motion. But what is 

 heat, that it should work such changes in 

 moral and intellectual nature? Why are we 

 unable to read " Mill's Logic " or study the 

 " Kritik der reinen Vernunft " with any 

 profit in a Turkish bath? Heat, defined 

 without reference to our sensations, is a 

 kind of motion, as strictly mechanical as 

 the waves of the sea, or as the aerial vibra- 

 tions which produce sound. The communi- 

 cation of this motion to the molecules of 

 the brain produces the moral and intel- 

 lectual effects just referred to. Human ac- 

 tion is only possible within a narrow zone 



of temperature. Transgress the limit on 

 one side, and we are torpid by excess; 

 transgress it on the other, and we are tor- 

 pid by defect. The intellect is in some 

 sense a function of temperature. Thus at 

 noon we were drained of intellectual en- 

 ergy; eight hours later the mind was 

 awake and active, and through her opera- 

 tions was shed that feeling of earnestness 

 and awe which the mystery of the starry 

 heavens ever inspires. Physically consid- 

 ered, however, the intellect of_noon differed 

 from that of 8 p. m. simply in the amount 

 of motion possessed by the molecules of the 

 brain. TYNDALL Hours of Exercise in the 

 Alps, ch. 5, p. 61. (A., 1898.) 



398 . BRAIN, HEMISPHERES OF, SPE- 

 CIALIZED Right-handed People Are Left- 

 drained. Most people, in fact, are left- 

 brained, that is, all their delicate and spe- 

 cialized movements are handed over to the 

 charge of the left hemisphere. The ordi- 

 nary right-handedness for such movements 

 is only a consequence of that fact, a conse- 

 quence which shows outwardly on account 

 of that extensive decussation of the fibers 

 whereby most of those from the left hemi- 

 sphere pass to the right half of the body 

 only. JAMES Psychology, vol. i, ch. 2, p. 

 39. (H. H. & Co., 1899.) 



399. BRAIN NOT INVOLVED IN RE- 

 FLEX ACTION Breathing, the Beating of 

 the Heart, etc., Unconscious The Highest 

 (Cerebral) Force Economized. The reflex 

 actions breathing, the movements of the 

 intestines, the heart's action, winking, etc. 

 are known to be stimulated through the 

 spinal cord, and its immediate continua- 

 tions at the base of the brain; they do not 

 involve the cerebral mass. The responding 

 movements in the case of each of them are 

 limited to the work to be done : to the chest, 

 in breathing; to the intestines, in propel- 

 ling the food; to the muscles of the heart, 

 in pumping the blood. These actions are 

 unaccompanied with feeling. So, in touch- 

 ing the hand of one asleep, we see the hand 

 curl up, or the arm move away. This is 

 called reflex; it is prompted through the 

 lower centers, without lateral diffusion or 

 communication, and it is directed to a sin- 

 gle local group of muscles. In such ex- 

 amples, as formerly seen, the limitation is 

 owing to want of force. There are ways 

 open to the brain ; but they are not entered 

 at the instance of a very feeble contact. 

 Still, the fact of limitation of range is ac- 

 companied by the fact of unconsciousness: 

 an isolated response is our evidence for con- 

 traction of the sphere of excitement; and 

 such isolated responses are little, if at all, 

 accompanied with feeling. BAIN Mind and 

 Body, ch. 4, p. 14. (Hum., 1880.) 



400. BRAIN OF MAN AND OF APE Ab- 

 solute and Relative Differences. So far as 

 I am aware, no human cranium belonging to 

 an adult man has yet been observed with a 



