344 



KNOWLEDGE 



[Dec. 7, 1883. 



We will begin with touch. 



Dr. Kussruaul and others hold that from the very begin- 

 ping touch is a finely-developed sense, and Mr. Sully goes 

 ao far as to hazard the suggestion that even taste is at first 

 scarcely differentiated from it. Professor Preyer, however, 

 maintains that at birth there is such a low degree of skin 

 susceptibility, that the nose, hands, and lips of the new- 

 born infant may be pricked with impunity — the child 

 neither starting, nor betraying any other sign of dis- 

 comfort. 



The Professor did not himself try this experiment, nor 

 MTOuld we counsel our readers to do so ; but he claims to 

 have arrived by other roads at the same conclusion, one of 

 his proofs being that the infant does not blink when the 

 water of its bath splashes into its eyes. 



Without expressing any opinion as to the soundness of 

 the professor's deductions, we will content ourselves with 

 saying, that every one — Professor Preyer included — agrees 

 that within three days of birth the child's skin suscepti- 

 bility is very great, particularly for those tactile sensations 

 which are most closely connected with sensations of tem- 

 perature, and which are involved in the contact of the 

 child with its nurse's or mothei's body. Grimaces and 

 movement moreover testify to the fact that the sensation 

 of tickling is soon felt in full intensity under the appro- 

 priate stimulus. Darwin, when one of his children was 

 seven days old, tickled the naked sole of its foot with a 

 piece of paper, whereupon the child jerked its foot away 

 and curled its toes as older children do when tickled. 

 Perez again noticed that in the very youngest children 

 disagreeable tactile sensations would call forth grimaces. 

 Altogether, then, we may consider there is fair ground 

 for saying that touch is not one of the tardily developed 

 senses. 



Far otherwise, however, is it with sight. If we are to 

 believe some of the statements made on the subject, this 

 sense requires for its development twenty or thirty days. 



At birth, of course, no child sees, — so far all authorities 

 concur. But, while Dr. Kussmaul and Professor Preyer 

 declare that a child cannot fix an oliject — that is, 

 cannot " bring the eye into such a position that the 

 image of the object may fall upon the point of most 

 distinct vision in the centre of the retina " — before it is 

 three weeks old ; and Perez and others, going further, say 

 not before the end of the fourth week, — Darwin, on the 

 other hand, declares that his child's eyes were fixed on a 

 candle as early as the ninth day, and Mr. Sully asserts, in 

 reference to the infant Clifford, that on the second day " the 

 previously futile attempts to bring the two eyes into har- 

 monious action were crowned with a measure of success, 

 and they were observed to converge for an instant on the 

 father's face if held invitingly near. By the fourth day the 

 command of the eye was far greater, and it was possible to 

 notice the effect of an object in attracting the organ 

 in a particular direction, if not too far from that of the 

 point previously looked at." 



Equally great difference of opinion prevails with regard 

 to the act of turning the head towards the light. 

 (i. H. Lewis affirms that it takes several days before 

 the child makes any movement of the head towards the 

 light, and Prof. Preyer sets the limit at six days ; but 

 Dr. Kussmaul states that he saw one child perform 

 this act on the second day, and his observation is borne 

 out by the testimony of the philosopher Tiedemann, who, 

 a hundred years ago, noted that his infant son sought 

 the light from the very beginning. It is perhaps only just 

 to mention that Tiedmann's son grew up later into as 

 eminent a man as his father, and it may, therefore, well be 

 urged that he was what nurses call a forward child, and no 



criterion for others. But making due allowance for this, 

 we have still before us evidence of a very conflicting kind. 



This much, at least, is clear, that it usually requires 

 between two and three weeks for the sense of sight to come 

 into full operation, and that its gradual development takes 

 place somewhat in this wise. 



From the very first there is a slight but appreciable sus- 

 ceptibility for sensations of light, as is proved by the two 

 facts, that the pupil of the babe's eye contracts under the 

 influence of strong light, and that in some instances sleep- 

 ing infants, when two or three days old, have been made to 

 screw up their eyes, .start, and wake, when a candle has 

 been brought near their closed lids. Now, this sensibility 

 of the eve to light induces vague spasmodic movement on 

 the part of that organ, and out of these movements the 

 fixing of the eye upon objects gets gradually developed. 

 The eyes of the new-born child move (juite independently 

 of each other, the one going to the left, the other to the 

 right, and one sometimes moving alone, but little by little 

 symmetrical action is evolved. The following a moving 

 object with the eye is a later acquisition, and the colour 

 sense is also somewhat in abeyance. It is an open question 

 what colours children are most attracted by ; some prefer 

 yellow, some red, but there is no doubt that they are all 

 repelled by black. The power of accurately discriminating 

 red, green, yellow, and blue is not manifested. Professor 

 Preyer says, before the beginning of the child's third year. 



The moving object attracts the child's attention more 

 quickly than the stationary one, even though the latter 

 chance to be brightly coloured. The more complex sensa- 

 tions of sight — the sensations of form, apparent size, dis- 

 tance, volume, and position are all late manifestations, for 

 the child of ten or eleven months will stretch out its arms 

 and try to grasp the moon ; and will even in its third year 

 make futile efforts to thrust large playthings into small 

 boxes. 



When we pass from sight to hearing, we find almost 

 perfect agreement amongst psychologists. The infant, as 

 we have had occasion to say before, is born perfectly deaf, 

 but within three days of birth becomes so sensitive to 

 sound, that any sudden noise will make it start and blink 

 its eyes. In the child Clifford a distinct movement of the 

 head in response to sound was observed on the second 

 day. Darwin tells us that in the case of his child, sounds 

 made it start and wink its eyes much more frequently than 

 did sight. But he goes on to add, " Although so sensitive 

 to sound iu a general way, he was not able, even when 124 

 days old, easily to recognise whence a sound proceeded, so as 

 to direct his eye to the source." Children are very early 

 pleasantly excited by music or .singing, Tiedemann's son 

 showing the greatest liveliness and joy when, forty days 

 after birth, he heard the piano played for the first time. 

 Perez points out that clear, .tinkling sounds, especially 

 when repeated rhythmically, never fail to give pleasure. 

 Discordant, shrill, deafening noises, however, when once 

 they cease to alarm by their newness, do not seem to offend 

 the infant's ears, as they do those of the adult — a truth to 

 which all can testify who have had much to do with 

 healthy young children, and have learnt by rather disagree- 

 able experience that " everything does for them to make a 

 noise with." A. M. H. B. 



The Largest Locomotive in the World. — This is 

 now being constructed in the Sacramento carriage-building 

 shops of the Central Pacific Railway. It will weigh 73 tons, 

 and have five pairs of driving-wheels. The tender will 

 weigh 25 tons, and the total length of engine and tender 

 will be 65 feet. 



