292 



NA TURE 



[January 25, 1906 



tion ; the ninety and nine ask for a "cure." Yet 

 whilst prevention is often within reach, cure, in 

 the proper sense of the word, is frequently impossible. 

 I In diagnosis of the disease must be left to the 

 skilled expert, the means of prevention should be 

 known to all intelligent cultivators, the remedy may 

 be prescribed by the plant-doctor, whilst the " cure," 

 which often means the bonfire, may be entrusted to 

 the labourer. 



Another point which cannot be overlooked in con- 

 sidering; the prevention of epidemic diseases is the 

 necessity for concerted action. If one cultivator is 

 alive to the exigencies of the case his labour is often 

 vain if his neighbour be slovenly and apathetic. 



The book before us is divided into two parts, the 

 first dealing with the fungi which are injurious to 

 plants generally, the second with the specific diseases 

 of Minnesota vegetation. The account of the nature, 

 mode of growth, and habits of fungi is written clearly 

 and in a style readily comprehensible bv the reader 

 of average intelligence. It forms, indeed, an excel- 

 lent introduction to the studv of fungi. 



A si parate chapter is given to the history of the 

 bacteria which presents in a concise form many de- 

 tails of the utmost importance to cultivators. After 

 these generalities attention is directed to the fungous 

 diseases most prevalent in Minnesota. To these we 

 need not heir specially refer, nor to the sections on 

 fungicides and spraying apparatus. We can only 

 add that the book is well illustrated and provided 

 with a copious index. We commend it to the notice 

 of all who are interested in plant-diseases, and 

 especially to foresters and cultivators of field or garden 

 plants. 



OUR BOOK SHELF. 

 Mesure et Ddveloppement de I'Audition. Bv Dr. 



Marage. Pp. nq. (Paris, 1905.) 

 Tins small volume by Dr. Marage is of scientific 

 value inasmuch as it contains an account of a method 

 by which acuteness of hearing can be measured, and 

 by which any degree of deafness can also be stated 

 with accuracy. Aurists for many years have made use 

 of the ticking of a watch, tin sound of a tuning-fork, 

 or a percussion sound as a source of sound, and thev 

 state the degree of deafness by a measurement of the 

 distance at which the patient can hear the sound as 

 compared with the efficiency of a normal ear. The 

 best of all acoumeters, no doubt, is the human voice, 

 as it gives sounds to which the ear is adapted; but 

 no two human voices are alike, in consequence of 

 the variations in quality caused by the vocal resonating 

 cavities. 



Dr. Marage, however, has invented a siren which 

 is furnished with resonating masks (casts of the 

 vocal cavities as adapted fur the vowels OU, O, A, 

 E, and I). This apparatus niters these vocal tones 

 with singular purity. The form of the mask, and 

 especially that of the oral opening in each case, sup- 

 presses most, if not all, of the overtones for each vowel, 

 and the laryngeal vowel tone (produced bv the siren) 

 is alone sounded. Further, he has shown that the in- 

 tensit) of the sound of this instrument, as measured 

 by a special water-manometer, is proportional to the 

 pressure of the air which traverses the apparatus. 

 The siren can be adjusted for any vowel, and the 

 apparatus is always at the same distance from the 

 ear. The measurement of the auditive acuity is given 

 NO. 189I, VOL. 73] 



in I he number of millimetres of water shown in the 

 manometer when the sound of the particular vowel is 

 heard. Thus any vowel sound is heard with a 

 pressure of 1 mm. by a normal ear; if the pressure 

 must be raised to 40 mm. before the sound is heard 

 the auditive acuity is 1/40, if at 60 mm. 1/60, if at 

 200 mm. 1/200, and so on. 



1 )r. Marage also shows an ingenious method of 

 recording on a chart the degree of acuity for each 

 vowel, always in mm. of water, and if the points 

 for the various vowels are joined a curve is pro- 

 duced. The form of this curve varies with different 

 pathological conditions of the middle and internal 

 ear, so that after the patient's ear has been tested 

 for the vowel tones by the siren, and the curves have 

 been plotted out, the form of the curve is of value 

 In diagnosis. Lastly, Marage uses the siren to 

 massage the drum-head and chain of bones by giving" 

 to the ear for a certain time, say a daily massage of 

 ten minutes, using the vowel tones of the instrument, 

 and he asserts, and shows by charts, that in a large 

 percentage of cases of many forms of ear trouble, and 

 in some cases even of deaf mutism, there is benefit 

 derived from the massage treatment. These results 

 cannot be criticised in a scientific journal, as thev 

 pertain more to the region of the practical aurist, but 

 there can be no doubt of the value of the method of 

 Marage as a tnethod of accurately determining acute- 

 ness of hearing. John G. McKendrick. 



American Insects. By Vernon L. Kellogg. Pp. 



vi + 674; 812 illustrations and 13 plates. (New York : 



Holt and Co.; Westminster.: A. Constable and Co., 



Ltd., 11)05.) Price 21s. net. 

 Tins work is intended as an introduction to North 

 American entomology. It consists of a systematic 

 review of the various orders of insects met with in 

 America north of Mexico, and of introductory and sup- 

 plementary chapters dealing with special subjects. 

 The three introductory chapters on structure, physi- 

 ology, development and classification are well done, a 

 great ileal of information being condensed in these 

 50 or 60 pages. 



The supplementary chapters are, however, the best 

 part of the book. They are (1) insects and flowers; 

 (2) colour and pattern and their uses; (3) insects and 

 1I1 ease These subjects are treated in an intelligent 

 111 inner, with an absence of dogmatism that is very 

 commendable. 



In some parts of the work the author is a little more 

 rash. Thus he concludes his account of the slave- 

 making ant, Polyergus, with the dictum " specializa- 

 tion is leading Polyere;us to its end! " Whether this 

 is the case must be left to the future to decide. It 

 would have been simpler to say that Polvergus has 

 mandibles unsuited for industrial purposes, and cor- 

 relatively possesses slave-making habits that do not 

 appeal to he very successful. 



Of the systematic part of the work we cannot speak 

 so highly; this is chiefly due, it is only fair to sav, 

 in inadequate space. There are, as the author says, 

 10,000 kinds of beetles in North America, as against 

 1000 kinds of birds. It is small wonder that the 

 atti mpl to condense an account of 10,000 species and 

 their habits and life-histories into 54 pages does not 

 leave a satisfactory impression. The extensive orders 

 Coleoptera and Diptera have suffered most from their 

 abbreviation. The Coleopterous portion, moreover, 

 has not been adequately revised, the larva of a 

 Longicorn beetle being figured as a tvpe of the larvae 

 of (he Buprestidae. 



Notwithstanding these drawbacks, the work is 

 probably the best that exists for anyone desiring an 

 introductory work on North American insects com- 

 pressed into a single volume. D. S. 



