384 



SCIENCE 



[N. S. Vol. XXIX. No. 740 



that conserve and prize at their proper value their 

 priceless treasures of carbon. 



Allerton S. Cushman, 



Assistant Director 

 Office of Ptjbuc Roads, 

 U. S. Depaetment of Ageicultube 



MAGNETIC ROCKS 



While in soutliern Arkansas recently, 

 studying the northern outcrops of the oil- 

 bearing horizons of Louisiana, I took occa- 

 sion to ascertain whether the peridotite erup- 

 tives about Murfreesboro, Arkansas, were as 

 magnetic as similar rocks in central New 

 York. They prove to be so; hence it seems 

 that if a somewhat detailed magnetic survey 

 of the region thereabout were made the tens 

 of thousands of dollars now expended in 

 worthless options might practically all be 

 saved. Naturally in searching for diamonds 

 the first information desired is the where- 

 abouts of the volcanic necks bearing the dia- 

 mond dirt. Though these are covered by 

 plateau gravel or alluvial sands and clays 

 they can be detected as readily as the dikes in 

 central New York can be located though under 

 many feet of glacial till. 



G. D. Harris, 

 Geologist to Louisiana 



A NEW PHENOMENON IN ELECTRIC DISCHARGE 



During last May the writer used a wire of 

 platinum having a diameter of 0.005 cm., in 

 some work in electric discharge around a right 

 angle in a wire. The discharges were made 

 non-oscillatory in character, by introducing 

 into the circuit a couple of strips of cloth 

 such as is used for surgical bandages. These 

 strips, which were in multiple, connected two 

 tumblers containing salt solution, one of which 

 was about 20 cm. above the other. 



During about three weeks of use, a system 

 of wavelets formed along the whole length of 

 the wire. They were very uniform in dimen- 

 sions. The wave-length was 0.090 cm., and 

 the amplitude from crest to crest was 0.015 

 cm. The wire was under tension of four 

 grams weight, by means of silk threads passing 

 over pulleys. 



The writer is under the impression that the 

 irregular bending of wires traversed by a con- 



tinuous current has been observed, but is un- 

 able to find a reference to it. 



Francis E. Nipher 



the dating op publications 

 To THE Editor of Science: Through acci- 

 dent or policy, the Carnegie Institution has 

 not dated many of its recent publications. 

 In bibliographical citations, where dates are 

 used to designate publications, it is difficult 

 to dispose of papers where the time of publi- 

 cation is not given. Moreover, is it not de- 

 sirable to date articles, to protect the writers 

 in priority? Max Morse 



The College of the City of New York, 

 February 2, 1909 



8GIENTIFIG BOOKS 

 Die MetamorpJiose der Inselden. Von P. 



Deegener. Pp. 56. Leipzig u. Berlin, B. 



G. Teubner. 1909. 



This little book, by one who has written 

 several valuable articles on the development 

 of the alimentary tract of insects, is one of 

 the most thoughtful and suggestive of a num- 

 ber of recent general accounts of Hexapod 

 metamorphosis. The author adopts the now 

 usually accepted view, advanced by Fritz 

 Miiller in 1864, that the larvse and pupse of in- 

 sects represent cosnogenetic adaptations, the 

 result of a tendency, so to speak, on the part 

 of an originally monomorphic form, to be- 

 come strongly trimorphic during its ontogeny. 

 In other words, the more specialized insects 

 (Holometabola) have found it increasingly 

 advantageous to assume three successive 

 forms during their metembryonic develop- 

 ment: the first, or larva, being devoted to ali- 

 mentation and growth, and often exhibiting 

 peculiar modifications to suit the highly 

 specialized environment in which it lives, the- 

 third, or imago, being devoted to the repro- 

 duction and dissemination of the species, and 

 the second, or pupa, providing for the trans- 

 formation necessitated by the two other very 

 different stages. 



Deegener's work is divided into three parts : 

 an analysis of the organization of the larva, a 

 consideration of the phylogeny of metamor- 

 phosis and of the significance of the pupal 

 stage. He recognizes three kinds of larvser- 



