NOVEMBEB 8, 1907] 



SCIENCE 



635 



tainly it is one in which every intelligent man 

 and woman should take an active part. 



Professor Howell in the last lecture treats 

 of " the cause of the heart beat." After 

 dwelling for some time upon the arguments 

 for the two theories, the myogenic and the 

 neurogenic, he concludes that the weight of 

 evidence is in favor of the former. Then, he 

 discusses the deeper and more fundamental 

 question of the initial cause, whether acting 

 through the nerve or directly on or in the 

 muscle. He calls attention to the influence of ■ 

 the inorganic salts, especially those of calcium, 

 first observed by Einger and concludes as 

 follows : 



The well-nourished heart contains a large sup- 

 ply of energy-yielding material, which is in stable 

 form, so that it neither dissociates spontaneous- 

 ly, nor can be made to do so by the action of 

 external stimuli. It is possible that this stable, 

 non-dissociable form consists of a compound be- 

 tween it and the potassium or the potassium salts 

 and that herein lies the functional importance of 

 the large amount of potassium contained in the 

 tissue. This compound reacts with the calcium 

 and sodium salts, and a portion of the potassium 

 is replaced and a compound is formed which is 

 unstable. At the end of the diastolic period this 

 eompound reaches a condition of instability such 

 that it dissociates spontaneously, giving rise to 

 the chain of events that culminates in the normal 

 systole. This dissociation may be made to take 

 place prematurely by an external stimulus, such 

 as a mechanical or electrical shock applied to the 

 keart at any time after diastole has begun. 



The first course of lectures before the 

 Harvey Society forms a valuable contribution 

 ki medical science and the members are to 

 be congratulated on their wise selection of 

 lecturers. Victor C. Vaughan 



Deutsches Bdderhuch. Prepared with coop- 

 eration of the German Imperial Health 

 Office. Quarto. Pp. civ + 536 and 13 

 colored plates. Leipzig, Weber. 1907. 

 Price 15 M. 



It is believed that this book will prove of 

 interest to scientists engaged in various lines 

 of work. It is the joint work of a number of 

 distinguished chemists, clinicians, pharma- 



cologists, geologists, meteorologists, etc., and 

 is designed to give a complete, impartial ac- 

 count of the leading German baths and min- 

 eral springs from various points of view. The 

 greater part of the volume is occupied by 

 detailed chemical analyses, but with these is 

 given much valuable information concerning 

 the geology, climatology, etc., of the individual 

 springs. Especially noteworthy and of very 

 general interest are the introductory chapters 

 on geology, chemistry, climatology, pharma- 

 cology, and general therapeutic uses of baths 

 and mineral springs; there is also a short 

 chapter on the radioactivity of mineral 

 springs. 



An examination of this volume will well 

 repay any one whose work is connected in any 

 way with this subject. The economic impor- 

 tance of this subject is indicated by the fact 

 that nearly $100,000,000 are spent annually 

 at the German baths and springs. 



E. H. 



Further Researches on North American Ac- 

 ridiidce. Professor A. P. Morse. Publi- 

 cation No. 68 of the Carnegie Institution, 

 Washington, 1907. 



The second report on North American Ac- 

 ridiidsB by Professor A. P. Morse is an inter- 

 esting pamphlet of 54 pages, a frontispiece 

 and nine plates. This, like the first report, 

 is a well-prepared paper and treats of the 

 acridiian fauna of the central southern states. 

 General notes on the regions traversed and 

 the life zones of localities visited are followed 

 by a discussion of locust coloration and varia- 

 tion. Habits and habitats are discussed in 

 connection with various local lists and then 

 follows a detailed list of localities at which 

 collecting was done and an annotated list of 

 the 124 species of Acridiidce taken. The plates 

 are from photographs taken by the author and 

 represent typical habitats of some of the spe- 

 cies taken. A. N. Caudell 

 U. S. National Museum 



Catalogue of Type and Figures, Specimens of 

 Fossils, Minerals, Rocks and Ores. George 

 p. Merrill. TJ. S. Nat. Mus., Bull. 53, Part 

 II., Washington, 1907, pp. 370. 



