622 



SCIENCE. 



[N. S. Vol. XVII. No. 433 



interested in its welfare. Ernest Lowe, of 

 the Plymouth Museum, describes ' The Eegis- 

 tration and Numeration of Museum Speci- 

 mens' as practiced in that institution and 

 the editor invites other papers on that subject. 

 'An Outsider's View of Museums and the 

 Public' suggests that the latter does not ap- 

 preciate the instruction to be found in mu- 

 seums. The balance of the number is filled 

 with notes regarding British and foreign 

 museums. 



The Plant World for March contains the 

 fourth instalment of 'Notes from the Note 

 Book of a Naturalist in Guam,' by William 

 E. Safford; ' Another Use for the Eoyal Pahn,' 

 by William Palmer; 'Spontaneous Fission of 

 Olive Trees in Palestine,' by Charles A. White, 

 and ' Botanizing in a Cactus Bed,' by Charles 

 E. Saunders. 



In the Proceedings of the American Acad- 

 emy of Arts and Sciences W. E. Castle gives 

 a very clear exposition of the main features 

 of 'Mendel's Law of Heredity,' accompanied 

 by illustrations of its workings. It is only 

 to be regretted that this useful paper is not 

 published where it would be more generally 

 accessible to the many who wish to know just 

 what Mendel's law is, but do not care to spend 

 the time to look up articles relating to it. 



Number 9 of Volume V. of the Memoirs 

 of the Boston Society of Natural History is 

 devoted to a detailed description of ' The 

 Skeletal System of Necturus maculatus/ by 

 Harris H. Wilder. This is accompanied by 

 several plates which admirably illustrate the 

 features of the skeleton. The author hopes 

 that as occasion offers he may add to this 

 papers on other systems of Necturus and thus 

 give a complete monograph of a typical tailed 

 amphibian. 



800IETIE8 AND ACADEMIES. 



AMERICAN PHYSICAL SOCIETY. 



The regular winter meeting of the Physical 

 Society was held at Columbia University, 

 New York city, on February 28, 1903. 



In a paper on the ' Nucleation of the Atmos- 

 phere During Cold Weather,' by Carl Barus, 



the author presented the results of recent 

 work with his coronal methods of counting 

 the number of condensation nuclei in the air. 

 These nuclei were found to be present in ab- 

 normally large numbers during the very cold 

 weather of December and January. Curves 

 were exhibited showing a remarkable parallel- 

 ism between fall of temperature and rise of 

 nucleation. Three alternative hypotheses 

 were mentioned by Professor Barus in ex- 

 planation of the results, viz., a current from 

 the upper air rich in nuclei may be brought 

 down by the cold wave; or the formation of 

 water nuclei may bring down an air stratum 

 overlying cities; or the water nuclei may be 

 radioactive at low temperatures and thus pro- 

 duce other nuclei by ionization. Experiments 

 are in progress to test the latter hypothesis. 



A second paper by the same author dealt 

 with the ' Ionization and Nucleation of the 

 Phosphorous Emanation.' The resulta show 

 that while the ionization produced vanishes 

 very quickly, the coronas due to condensation 

 on the nuclei present last for a relatively long 

 period. In this case, therefore, there appears 

 to be no relation between ionization and 

 nucleation. 



Professor Barus also described an interest- 

 ing and simple ' Method of Determining the 

 Eatio of the Velocities of the Ions in Air,' de- 

 pending on the rate of dissipation of charge 

 from a point. The value obtained for the ratio 

 of the velocity of the negative ion to that of 

 the positive ion was 1.32, which agrees closely 

 with the values obtained by other methods. 



A paper on ' Diffusion and Supersaturation,' 

 by H. W. Morse and G. W. Pierce, described 

 quantitative experiments based upon an ex- 

 periment originally due to Liesegang. When 

 the end of a capillary tube containing a solu- 

 tion of potassium chromate is dipped into a 

 water solution of silver nitrate, the silver 

 nitrate diffuses up into the tube and throws 

 down a precipitate of silver chromate. The 

 silver chromate, instead of growing contin- 

 uously as diffusion proceeds, forms in distinct 

 layers widely separated in comparison with the 

 thickness of the layers. Measurements were 

 made of the distances between these layers 

 and the time was observed at which each sue- 



