SCIENTIFIC LITERATURE. 



707 



length. This discussion contains much in. 

 teresting matter bearing upon the history of 

 glacial theory, the subject at the time Tyn- 

 dall wrote being in heated controversy. In 

 order that the pages now reproduced might 

 contain nothing touching the views of others 

 which Prof. Tyndall might have wished at 

 the present time to alter or omit, his widow 

 submitted the historical parts to Lord Kelvin, 

 who assures her that, in his opinion, " the 

 statements on controversial points in this 

 beautiful and interesting book of your hus- 

 band's are all thoroughly courteous and con^ 

 siderate of feelings, and have been felt to be 

 so by those whose views were contested or 

 criticised in them." The beginning of Tyn- 

 dall's study of glaciers proceeded from a dis- 

 course on slaty cleavage which he delivered 

 at the Koyal Institution, in June, 1856. This 

 discourse is appended to the volume. Some 

 sixty simple illustrations aid in making clear 

 the text. 



Dr. H. Holhrook Curtis's work on Voice 

 Building and Tone Placing * relates to the 

 singing voice. The author has invented a 

 method of tone exercises for overcoming se- 

 rious affections of the vocal cords which has 

 been used satisfactorily by the most re- 

 nowned singers, and he furnishes here an 

 exposition of the physiological principles, 

 and the elementary laws of sound and music, 

 on which it is based. The chapters on anat- 

 omy and respiration are intended to be of 

 value to the physician as well as to the stu- 

 dent of singing; and for that reason also 

 the subject of the vibration of the vocal 

 cords has been considered in a way in 

 which it is not entered into in any other 

 work. The author's theory that the over- 

 tones introduced by the proper method of 

 placing tones in the facial resonators induce 

 a new plan of vibration of the vocal cords 

 has recently been verified by the investiga- 

 tions of Prof. Oertel, of Munich, and several 

 of his experiments have been introduced to 

 explain the true plan of vibration of the 

 cords as seen in the stroboscope. The au- 

 thor has also tried, with the aid of these ex- 

 periments, to elucidate his theory as to the 

 removal of " singers' nodules " by tone ex- 



* Voice Building and Tone Placing. By H. 

 HolbroGk Curtis, M. D. Pp. 215, 12mo. New 

 York : D. Appleton & Co. Price, $2. 



ercises in a scientific way. The general 

 scheme of the building of the voice, in ac- 

 cordance with the author's theory of tone 

 placing, is appended for the benefit of teach- 

 ers and students. The book is the result of 

 a vast experience with singers. The ideas 

 have been put together in a concise and 

 simple way, without any attempt at elabo- 

 ration of style. The closing chapter, on 

 Voice Figures, in which the vibrations are 

 translated into pictures of great variety and 

 beauty, has more than a physiological or 

 acoustic interest. It is a revelation of the 

 grace and assthetic charm with which Na- 

 ture's processes are found to be invested, 

 whenever we are able to recognize them. 



In his discussion of the Primary Factors 

 of Organic Evolution* Prof. Cope attempts 

 to select from the mass of facts accumulated 

 by biologists those which, in his opinion, 

 throw a clear light on the problem of or- 

 ganic evolution. As the actual lines of de- 

 scent can be finally demonstrated chiefly 

 from paleontological research, a large part 

 of his evidence is drawn from that source. 

 Another reason for preferring the paleon- 

 tological evidence is that Darwin and his 

 school have drawn their evidence from cecol- 

 ogy and Weismann and writers of his type 

 from embryology, leaving the paleontologi- 

 cal field less worked. The mass of facts re- 

 cently brought to light in the field of pale- 

 ontology, especially in the United States, 

 remained to be presented, and the evidence 

 they contain to be interwoven with that de- 

 rived from the sources mentioned. The 

 view is accepted, to which many zoologists 

 are now inclined, that the factors of evolu- 

 tion which were first clearly formulated by 

 Lamarck are reallj such ; and the research 

 has proceeded on the assumption that every 

 variation in the characteristics of organic 

 beings, however slight, has a direct efllicient 

 cause. Any theory of evolution which omits 

 the explanation of the causes of variations, 

 Prof. Cope holds, is faulty at the basis. 

 Hence the theory of selection can not answer 

 the question asked, although it embraces an 

 important factor in evolution. The subject 

 is considered under the several headings of 



* The Primary Factors of Organic Evolution. 

 By E. D. Cope, Ph. D. Pp. 547, 12mo. Chicago : 

 Open Court Publishing Company. Price, g2. 



