June 17, 1909] 



NA TURE 



457 



until the date 1 mention, when I was resident medical 

 oflicer to a large London hospital. 



Working as I was frequently until a late hour in the 

 pathological laboratory, which opened off the entrance 

 hall, 1 had, in order to reach my room, to cross the hall 

 obliquely and enter the corridor by a wide door, some 

 t> feet wide, with folding glass doors, which were, as a 

 rule, fastened back. The hall and corridor were unlighted. 

 I usually walked well out into the hall from the door of 

 the pathological laboratory, turned to the right when I 

 thought I was opposite the door opening into the corridor, 

 and then walked straight forwaid between the doors. I 

 found, a good deal to my surprise, that though in the 

 dark (even though I shut my eyes) I could judge as I 

 walked through, very accurately, to which of the two 

 doors I was nearest. I made a large number of observa- 

 tions, and the constant result was sufficient, 1 think, to 

 preclude any idea of mere coincidence. 1 found I could 

 even form a trustworthy estimate if I was only a few 

 inches nearer one side than the other ; and, further, if I 

 gradually moved towards one or other side, when I got 

 within a few inches of the door I " felt " that I was 

 getting very close to it. The way in which I felt this 

 is difficult to describe, but the sensation of " nearness " 

 was situated in my face, on my forehead and cheeks, and 

 seemed to be particularly keen on turning my cheek in 

 the direction of the surface that I was approaching. The 

 conclusion that I came to was that there were two different 

 processes involved; in the first case (i) the nearness of a 

 solid body was made evident by difference in the reflection 

 and resonance of my footsteps as I walked, and in (2) the 

 differences in the reflection of the heat of -the face from 

 a surface at varying distances were the cause of the 

 sense of nearness or farness. It will be seen that I had 

 arrived at almost precisely the explanation which Dr. 

 .McKendrick puts forward as the explanation of the power 

 of the blind to recognise their relation to e.\ternals. 



(i) To test my theory of sound reflection I tried the 

 effect of walking in stockinged feet, and found that it 

 sensibly diminished my power of recognising my position ; 

 this is, of course, quite analogous to the difficulty, which 

 Dr. McKendrick describes, experienced by the blind -when 

 there is snow upon the ground. A still more conclusive 

 lest of the correctness of the theory would be to go 

 through the same experiments with the ears effectively 

 stopped. 



Since I made these first observations I have noted many 

 other occasions on which minute sound changes have given 

 rise to a correct idea of relationship, .'\nyone may readily 

 prove for himself in walking in the dark or with the 

 eyes shut along a corridor with doors opening off it, some 

 of which are open and others closed, how easy it is to 

 recognise when one comes opposite one of the open doors, 

 and a very little consideration will convince him that the 

 explanation lies in the difference in resonance from the 

 walls of the corridor and from the space into which the 

 open door leads. .Again, I have more than once noticed, 

 when riding on top of a tram-car in the crowded city, 

 that I have been " sensible " of another passenger sitting 

 quietly down on the seat behind me, not through any 

 sound that he has made, but by his cutting off from my 

 cars a portion of the general roar of traffic. It is the 

 finer sound indications of this type, to which we custom- 

 arily pay little heed, since our eyes yield us more rapid 

 '.'nd more complete information, that convey so much 

 information to the blind, whose ears, if not more keen, 

 are more intent, and the blind man's stick undoubtedly 

 serves, not only to feel his way with, but by its tap to 

 supply a source of sound the resonance of which may be 

 noted. There is still much haziness, even among those 

 who have to do with the management of the blind, as fo 

 their psychology, and one superintendent of a blind 

 asylum with whom I am acquainted, indulging in that 

 mysticism which at the present day is so fond of explain- 

 ing phenomena, of which by experiment one may learn 

 something, bv theories of which we know nothing, would 

 drag in that blessed word " telepathy " to explain the 

 blind man's knowledge of surrounding objects. 



(2) The second principle involved, viz. the reflection of 

 the heat of the face from adjacent surfaces, is not so 

 i?aslly verifiable. 1 feel fairly confident, however, that 



accurate observations with a delicate surface thermometer 

 would show that the cheek was receiving a certain amount 

 of reflected heat as it was approached near to a solid 

 object. That the skin of the cheek is peculiarly sensitive 

 to the degree of temperature will be readily admitted by 

 anyone who has seen a laundress testing the proper heat 

 of her iron liy holding it to her face. Further, the repeti- 

 tion of the experiment with the use of a mask, which 

 would minimise the sensitiveness of the skin to changes 

 of temperature, has struck me as likely to give conclusive 

 results, and I am particularly interested to find this sup- 

 position supported by Dr. McKendrick 's statement that 

 the blind do not so readily avoid an obstacle if the face 

 is covered. Charles H. Melland. 



Manchester, May 29. 



The Pollination of the Primrose. 



I.N Nature of May 20 the reviewer, in the course of 

 his appreciative and mteresting notice of my book, " Life- 

 histories of Familiar Plants," states: — "We notice that, 

 without stating definitely what insect pollinates the prim- 

 rose, the author refers to the bee or moth as doing it, in 

 a misleading way. He would have been wiser to ask 

 readers to notice what insect is really effective in the case 

 of this plant. Neither honey-bees nor moths are known 

 to be so." Regarding this point, on p. 78 I have written 

 as follows : — " Now, watch the occasional bee that makes 

 a visit to these two different types of flowers. Here is 

 one alighting. With the sudden weight thus imposed 

 upon it the flower sways," &:c. This passage, of course, 

 refers to a humble-bee, as the reference to " the sudden 

 weight " clearly implies. It is true that I did not 

 definitely state that it was a humble-bee, but, on the , 

 other hand, I have nowhere in the chapter referred to 

 the honey-bee. 



Probably the reviewer, and also readers of Nature, 

 will be interested in the two following notes from my 

 diary for this year: — .-Vpril 21: "Saw the first small 

 white butterfly of the season, in garden, about 2 p.m. 

 It was sipping nectar from a primrose flower." (.Amongst 

 the photographs illustrating the book referred to above 

 it will be remembered that there is one showing a green- 

 veined while butterfly feeding amongst primrose flowers.) 

 May 3 : "A species of large, black humble-bee in 

 garden visiting only primroses and polyanthuses. Saw 

 five of them within the space of two yards. One was a 

 large female (the largest humble-bee that I have ever 

 seen), and was apparently entirely black. In some of 

 them, the pollen baskets stood out distinctly as yellow 

 patches on their legs. One other specimen had an orange- 

 coloured thora.x. " I could not at the time make a capture 

 of one of the bees, and as cold weather followed, and the 

 primroses had nearly done blooming, I did not see the 

 bees again. 



While possessing very little knowledge of the species of 

 humble-bees, I am inclined to think that the species I 

 saw was Bonibus harrisellus, the large specimen being 

 a queen, the one with the orange-coloured thorax a male, 

 and the remainder neuters. Perhaps some of your readers 

 can give some information regarding these bees, and may 

 have observed them on primroses. So far as my observa- 

 tions went, the bees confined their attention exclusively 

 to the primrose family. John J. Ward. 



Rusinurbe House, Somerset Road, Coventry, May 25. 



Referring to a question raised in Nature of May 20 

 (P- 345). the writer of the article " Recent Studies on 

 .Animal and Plant Life " may accept it as a fact that 

 the primrose flowers are visited both by humble-bees and 

 by moths, among which may be particularly named the 

 humming-bird anci bee hawk-moths. The flowers are also 

 frequented by dipterous insects, a specimen of one of 

 which is enclosed, by which, for the long-styled form at 

 least, pollination may perhaps be sometimes effected. 



. . W. E. Hart. 



Kilderry, Londonderry, Ireland, May 24. 



The determination of the insects that pollinate the prim- 

 rose is an old problem, and my remarks in the review 

 under consideration were made with the view of eliciting 



NO. 2068, VOL. 80] 



