December 15, 1892J 



NA TURE 



149 



plate, the coxa, the first joint being in fact the coxa and 



the trochanter, the short joint articulating it to the femur. 

 Then follow short sections on the metamorphoses of 

 insects and their habits and haunts, and longer sections 

 on the collecting and preserving of perfect insects and 

 larvae, which are far more correct than the preceding 

 ones, though very slight and quite insufficient for the 

 initiation of a beginner. The main part of the book is 

 devoted to short descriptions of the more prominent 

 British insects under their various orders and families, 

 and illustrated by twelve coloured plates, which are 

 decidedly good for cheap chromographic work ; this is by 

 far the most useful portion of the book, and well-marked 

 forms will easily be recognized from the figures and 

 descriptions, even though many species are placed in 

 their wrong families. 



Ostwald's Klassiker der Exakten Wissenschajten. Nos. 



31-37. (Leipzig: Wilhelm Engelmann, 1892.) 

 We have already called attention to this admirable series 

 of small volumes. It consists of scientific papers which 

 may be said to have marked definite stages in the 

 development of science. Ihe only fault we have to find 

 with the series, as we have already stated, is that only 

 the German papers are given in the language in which 

 they were originally written. All the others are trans- 

 lated. This is undoubtedly a mistake, for much may 

 often depend on the precise words used by a great 

 master of research. In other respects the series is 

 excellent, and should be of genuine service to scientific 

 students. The papers reproduced in the present set of 

 volumes are Lambert's " Photometrie," three volumes 

 (1760) ; photo-chemical researches, by R. Bunsen and 

 H. E. Roscoe (1855-59) ; an attempt to find the 

 definite and simple conditions in accordance with 

 which the constituent parts of inorganic nature are 

 connected with one another, by Jacob Berzelius 

 (1811-12) ; on a general principle of the mathe- 

 matical theory of induced electrical currents, by 

 Franz Neumann (1847) ; observations on the moving 

 power of fire and the machines fitted for the development 

 of this force, by S. Carnot (1824). 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended or this for any other part of Nature. 

 No notice is taken of anonymous <.ummunications.'\ 



" Aminol, a True Disinfectant." 



Will you grant me space, in order to avoid misunderstand- 

 ing, to make the following explanation? — 



(i) I recently learned that certain samples marked "Aminol, 

 a true disinfectant " have been sent to various gentlemen, 

 accompanied by a leaflet, in which my name, without my 

 authority, is associated with tho-e samples. Allow me to in- 

 form your readers that those samples contain "aminol" in 

 water in the strength of one in five ^thousand. Now, the ex- 

 periments which I carried out with " aminol," as regards its 

 disinfecting power of microbes, were made with a solution of 

 the strength of one in six hundred, and the disinfecting power 

 of this strength was the following: spores oi Anthrax bacilli 

 remained unaffected after eight hours' exposure, only after an 

 exposure for twenty-four hours did the number of living spores 

 decrease, but some escaped disinfection even after so long an 

 exposure. Anthrax bacilli. Staphylococcus aureus, and others 

 were destroyed, but only after a prolonged exposure. 



(2) A substance is advertised and circulated under the name 

 of " Periodate crystals," and is associated with my name with- 

 out my authority. Until quite recently I have made no experi- 

 ments wiih it. A few years ago I made a few experiments, 

 meiely of a tentative character, with a solution which was 

 labelled " Periodate," but not with the substance advertised as 



NO. 1207, VOL 47] 



'• Periodate crystals." With these latter I have recently made 

 experiments, and 1 find that their solution in full strength has 

 no disinfectingpower on microbes, pathogenic and non-patho- 

 genic, amongst which may be mentioned the bacillus and spores 

 of anthrax, the bacillus of typhoid and of diphtheria, of cholera 

 and of erysipelas, the Bacillus prodi^qiosus, the Staphylococcus 

 aureus, and others. Likewise I find that injection of large 

 quantities of the solution into guinea-pigs already infected with 

 anthrax or diphtheria, has no power whatever in arresting or 

 altering the normal course of these diseases to their fatal issue. 



E. Kl.EIN. 



Tracery Imitation. 



I TOOK occasion some months ago to publish the result of ob- 

 servations on my child H.'s progressive attempts at drawing after 

 outline " copies " set before her.^ Examination of the series of her 

 drawings made almost daily during the period from her nine- 

 teenth to her twenty-seventh month showed in them no apparent 

 form or shape. They are simply vigorous pencil markings, 

 answering as well to one " copy " as to another — or to none. 

 Quite suddenly, however, in her twenty-eighth month, she 

 seemed to catch the idea of breaking the " copy" (man) up into 

 parts, and succeeded in making head, body, arms, legs, &c., 

 in sufficient degree of relative proportion to show that here was, 

 in her case, the rise of what I called in the article cited, 

 ' ' tracery imitation " of a visual picture. 



At that time I had no explanation to offer, but simply 

 recorded the observation. I have now, however, reached a way 

 of explaining the rise of this apparently abrupt connection 

 between muscle-sense and sight — an explanation suggested to me 

 by a passage in Strieker's argument for the eye-movement theory 

 of the visual apprehension of figure or outline. - 



Before a child begins to acquire "tracery imitation," his 

 drawings have no shape, but they show uniformly certain 

 systems of angles, curves, &c., due to the easiest and most 

 natural movements of the arm. The eyes, however, have been 

 in a measure already educated to recognize certain shapes or 

 "copies." There are, therefore, in consciousness two series of 

 associations — one of eye-movement sensations, a, a\ a-, a-', a*. 

 Sic, with a certain strength of revival, which we may call x : 

 the other, an associated series of arm-movement sensations, 

 n, n\ «-, n^, «*, &c., representing a path of least resistance in 

 arm movement. Let us call its strength or degree of tendency 

 to progre.-sive revival y. 



Now, before the rise of "tracery imitation " y is greater 

 than X, for the reason that the arm is restricted to a very few 

 movements, and these are largely automatic. Once start one of 

 these movements, and the tendency to carry it out is very strong. 

 The tendency of the eye-movement series, on the contrary, to 

 regular revival is slight ; very few objects, copies, &c. , being so 

 clear and isolated as to give frequent unbroken reproductions. 

 Consequently, the arm-movement series, n, n\ n-, &c., wins 

 the day, and an abortive "drawing" is the result. 



But the time comes soon when the reverse is true — when x is 

 greater than ^y. The eye-movement series gets strengthened 

 constantly by the repeated explorat ion of familiar figures, 

 especially if, as in the case of my child, the eye be trained by 

 having the same "copies" set from day to day. On the other 

 hand, the arm and hand movement series gets constantly lesser 

 and weaker, since the increasing mobility of the muscles, in the 

 varied new activities of this period of infancy, is acquired at the 

 direct expense of the early "cast-iron" reactions which are 

 largely organic. Both of these tendencies were very marked in 

 H. — the first, in the more pronounced recognition of the 

 "copies " set before her ; the second, in the less uncouth manner 

 of holding her pencil, moving the fingers, disposing the arm, &c. 

 Hence, it is simply a matter of education that .r should 

 soon overweigh y, and the elements of the eye series 

 a, a^, a-, a^, &c., should draw after them the arm series. 



An association thus begins to be formed between the several 

 members of the a series and certain correct elements of arm sen- 

 sation : these latter go to form, under this leading, a new n 

 series, which gradually becomes independent as an acquisition 

 That each new tracery combination is thus learned separately 

 is seen in the fact that after H. learned to trace certain " copies " 

 (man, bird), she was yet entirely unable to trace any others. 



' Science, New York. January 8, iSgi. 



- " Du Langage et de )a Musique " (French ed.), chap. xxii. ; see also his 

 " Studien fiber die Association der Vorstellungeu." 



