Decesibkb 20, 1895.] 



SCIENCE. 



851 



blind from birth by dovible congenital cataract, 

 was operated on at the age of six years. After 

 removal of the bandages she saw at once, and 

 without learning by experience, all things in 

 their proper positions. Perception of direction 

 and position was immediate, but not so the 

 perception of the relative distance of obj ects. The 

 former is a primary gift of sight, the latter a 

 judgment and must be acquired by experience. 

 In this controversy we have again repeated the 

 three old views on this subj ect. 1 . The nativistic 

 theory : It is a direct endowment of the eye or 

 the brain, and there an end. This is the usual 

 popular view. 2. The empiristic theory: It is 

 acquired by individual experience, as we acquire 

 the proper manipulation of the glass slide under 

 the microscope. This is Prof. Minot's view. 3. 

 The metaphysical theory: It needs no explana- 

 tion at all. There is no such thing as up and 

 down for the soul. This last we put aside as 

 not a scientific solution. As to the other two, 

 they are completely reconciled and the ques- 

 tion, it seems to me, solved, as so many other 

 vexed questions are solved by evolution. It is 

 acquired — ^yes, but not by individual experience. 

 It is inherited — ^yes, but not without experience. 

 Now, as to the legitimacy of my own explana- 

 tion. A similar acquisition of ideas of direc- 

 tion or position in spaceby ancestral experience 

 inherited and fixed in structure has taken place 

 in all the senses, but especially in senses of 

 touch and sight. Is it not legitimate to reduce 

 these or their physical concomitants to a com- 

 mon law ? Prof. Cattell (Science for Nov. 15, 

 p. 668) objects that the different sensations are 

 wholly disparate and, therefore, they cannot be 

 explained the one in terms of another. This is 

 true of sensations proper, such as light, color, 

 sound, contact, etc., but it is not true of direc- 

 tion and position. These are not sensations; 

 they are not peculiar to one sense. These are 

 ideas underlying all the senses, gradually grown 

 up in the mind as the result of deliverances of 

 all the senses. They are not disparate for dif- 

 ferent senses. These ideas of direction and 

 position in space are indeed purely psychical, 

 true; but ought we not, if possible, to reduce 

 their physical concomitants to law? This is 

 what I have attempted to do. 



I do not, of course, hope to settle this question 



to the satisfaction of all. I only wish to show 

 that my explanation is not illegitimate as Prof. 

 Cattell thinks, nor unnecessary as Prof. Minot 

 thinks. 



In conclusion I confess I do not quite see the 

 relevancy of Prof. Minot's parenthetic re- 

 mark. I do not see in what way the turning 

 back of the retinal fibres to end in the rods 

 and cones in vertebrates — though not in in- 

 vertebrates — can affect the question of reference 

 back along the ray line. 



Joseph Le Conte. 

 Beekeley, Cal., November 29tb. 



MOUNTAIN CLIMBERS AND THE PEECEPTION OF 

 DISTANCE. 



To THE Editor of Science: I do not know 

 that the attention of psychologists has been 

 sufficiently called to the experience of mountain 

 climbers as bearing on the problem of the per- 

 ception of distance. Both Sir Martin Conway 

 in his recent book, 'The Alps From End to 

 End,' and M. Bonvalot in his book, 'Across 

 Thibet,' have some suggestive remarks of the 

 same general tenor on this subject, but I will 

 quote only those of M. Bonvalot, as they seem 

 on the whole the most pertinent. Speaking of 

 the highlands of Thibet, he says: " It is difficult 

 to imagine how hard it is to find one's way 

 among these highlands, where a man loses all 

 sense of perspective, his eye wandering over 

 immense spaces without seeing, at given dis- 

 tances, either trees, houses, human beings, ani- 

 mals, or edifices the height of which is known 

 to him. It is by the incessant and unconscious 

 comparison of such objects as these that he has 

 learned to form an idea of distance. Here in 

 the desert we have in a few weeks lost this 

 sense of distance which we had gained by the 

 experience of our lifetime. All that one sees is 

 so alike ; one hill is like another ; according to 

 the time of day a frozen pool either sparkles in 

 the sun or disappears, so that one does not 

 know whether it is large or small ; a little bird 

 fiuttering its wings upon a clod of earth looks 

 like a wild animal which has been lying down 

 and is getting up ; a crow flying away with its 

 prey in the morning mist seems to be a gigantic 

 condor carrying off a lamb in its claws, while 

 at sunset this same crow, cleaning itself on the 



