Januaet 4, 1907] 



SCIENCE 



31 



of three ice ages at widely separated times. 

 The Permian glaciation is already fairly well 

 known. Of the other two, one is probably 

 Devonian, the other Archean. The field evi- 

 dence is said to be convincing. ' The Texture 

 of Igneous Rocks ' is taken up by Whitman 

 €ross, J. P. Iddings, L. V. Pirsson and H. S. 

 Washington. They attempt to make the 

 -classification according to textures more sys- 

 "tematie, and to get rid of the prevalent vague- 

 ness and inexactness. Terms with exact 

 meanings are proposed and the whole put into 

 ■systematic shape. ' Natural Mounds ' is the 

 title of an article by Maurius E. Campbell. 

 The mounds occur on flat surfaces and are 

 low and broad, and very symmetrical. They 

 vary from 10 to 140 feet in diameter and 

 from a few inches to 5 or 6 feet in height. 

 They are of very wide occurrence. Various 

 iiypotheses of origin have been offered, but 

 many of them have little foundation. Of 

 ■eleven possible modes of origin the writer 

 ■eliminates all but the one which ascribes them 

 "to burrowing animals — ants or rodents. The 

 subject of 'Eock Folds due to Weathering' 

 is taken up by the same author. He shows 

 tow great the expansion is in ordinary weath- 

 •ering and how this often forces the surface 

 Tocks to buckle. ' The Geology of the Lower 

 Amazon Eegion ' is based upon Katzer's work 

 and that of some others and was written by 

 Charles Schuchert. As the title indicates, it 

 is a discussion of the general geology and 

 stratigraphy of the region and adds consid- 

 ■erably to our knowledge of Brazil. The De- 

 vonian and Carboniferous are discussed in 

 ■considerable detail, and lists of fossils given 

 for correlation. The last article is by George 

 Davis Louderback on ' The Eelation of Eadio- 

 activity to Vulcanism.' The important bear- 

 ing of the recently developed knowledge of 

 radioactivity on the problems of the geologist 

 is shown and discussed in some detail. The 

 writer believes that while much of the interior 

 heat of the earth may be explained by radio- 

 activity, the special phenomena of volcanoes 

 may not be so explained. 



The Journal of Comparative Neurology and 

 Psychology for November contains the follow- 

 ing articles : ' The Mode of Connection of the 



Medullated Nerve Piber with its Cell Body,' 

 by Oliver S. Strong. A plate is given illus- 

 trating the form of the axone between the cell 

 body and the medullary sheath. ' On the 

 Centers for Taste and Touch in the Medulla 

 Oblongata of Fishes,' by C. Judson Herrick. 

 Fishes like the catfish which detect their food 

 by the simultaneous action of both taste and 

 touch in the barblets and outer skin offer an 

 interesting problem in the examination of the 

 centers of correlation within the brain for 

 these diverse sensory tracts coming from the 

 same cutaneous areas. The analysis of these 

 centers in the medulla oblongata of Ameiurus 

 shows that the gustatory nerves from visceral 

 surfaces effect the usual secondary connections 

 with the visceral musculature, but those gusta- 

 tory nerves which come from the outer skin 

 make their secondary connections vnth the 

 primary tactile centers in the funicular nuclei, 

 so that a common efferent path from the 

 latter correlation center serves for both senses. 

 ' Modifiability of Behavior in Hydroides dian- 

 thus V,' by Ada Watterson Yerkes. The ex- 

 periments show that this annelid worm readily 

 learns by experience. Two short papers on 

 the ' Behavior of Gonionemus ' are contributed 

 by Max Morse and Eobert M. Yerkes respect- 

 ively. An editorial on the relation of the 

 newer work of the American school of com- 

 parative neurologists to human neurology and 

 a few book reviews complete the number. 



SOCIETIES AND ACADEMIES 



THE GEOLOGICAL SOCIETY OF WASHINGTON 



At the 182d meeting of the society on No- 

 vember 14, Mr. F. E. Wright presented in- 

 formally the results of a comparative study of 

 various methods in use for determining the 

 relative quantities of mineral constituents in, 

 rocks. 



The meeting was devoted to an account of 

 the Tenth International Geologic Congress, 

 held in Mexico City, September 7 to 14, 1906. 



Mr. George Otis Smith described ' The Excur- 

 sion before the Congress.' 



Mr. S. F. Emmons : ' The Excursion to Jorullo.* 



Mr. G. F. Beckee : ' The Sessions in Mexico 

 City.' 



Mr. T. W. Sx-i-NTON : ' The Excursions after the 

 Congress.' 



