Decembfb 20, 19071 



SCIENCE 



869 



quency of the demagnetizing current, the less 

 complete is the demagnetization. This effect 

 •f frequency is more marked in large bars and 

 in soft iron. 



3. A sufficient range for the demagnetizing 

 current carries the iron from just above the 

 " knee " of the induction curve down to the 

 lowest value to be studied. Hard iron and 

 steel require a relatively higher initial current 

 than soft iron. 



3. The demagnetizing current is best re- 

 duced in such a way that the induction de- 

 creases approximately uniformly. 



4. One initial demagnetization produces the 

 same results as a separate demagnetization 

 before each step in the induction curve. 



5. Even many thousands of reversals of the 

 magnetizing force to be studied do not accom- 

 plish the effect of demagnetization. 



After iron has been demagnetized the ap- 

 parent induction observed increases for a few 

 reversals, passes through a maximum, and 

 then decreases, approaching a lower limit 

 asymptotically. This final limiting value is 

 defined as the true induction. 



The influence on permeability determina- 

 tions of temperature, small mechanical vibra- 

 tions, magnetic viscosity, and the terrestrial 

 field are investigated, and it is shown experi- 

 mentally that these elements must be consid- 

 ered if an accuracy of one per cent, is to be 

 obtained. Their influence is greatest in the 

 steep part of the induction curve. 



E. L. Faeis, 

 Secretary 



THE BIOLOGICAL SOCIETY OP WASHINGTON 



The 433d meeting was held October 19, 

 1907, with President Stejneger in the chair. 



The single paper of the evening was offered 

 by Dr. E. D. Merrill, on " The Geographic 

 Distribution of Philippine Plants." The sub- 

 ject-matter presented was the outcome of five 

 years' experience of the author and others, 

 during which large collections had been made 

 and many of the islands visited. He first dis- 

 cussed the relations of the Philippine flora 

 with that of Hawaii and northern Australia, 

 noting the interesting fact that of many Au- 

 stralian types found, all were confined to the 

 high mountains of the island of Luzon. He 



then considered the relations with Celebes, 

 Borneo, Formosa and the Asiatic continent. 

 The great number of plants common to 

 Luzon and Formosa he thought might indi- 

 cate a former land connection. Similarly it 

 was thought that the Philippines might have 

 been connected with Queensland. Although 

 the flora of the high moimtains was Asiatic, it 

 was evident that the great migrations had 

 come from the south. 



A brief discussion followed on the distribu- 

 tion of Philippine animals. Dr. Stejneger 

 gave various reasons for considering reptiles, 

 batrachians and mammals the best guides in 

 determining former land connections. Judg- 

 ing by the reptiles, there is no indication of 

 a connection between Formosa and Luzon 

 since the Jurassic. 



Dr. Lyon, speaking of the manmaals, said 

 this group gave no indication of a connection 

 with Formosa. The mammals of the moun- 

 tains of Luzon are so peculiar that it is dif- 

 ficult to say what their relationships are, but 

 their strongest leanings seem toward Austra- 

 lian types. 



Mr. Oberholser spoke of the birds, of which 

 there are about YOO known species represent^ 

 ing 175-200 genera. They may be divided 

 into Cosmopolitan, Palearctic and Philippine 

 groups. The latter comprises the following 

 subdivisions: (1) East Asian, with few species, 

 (2) Australasian, with rather few, (3) Cele- 

 besian, with somewhat more, (4) Bornean, 

 with a stiU greater number, (5) Indo-Malayan, 

 with the largest of all, (6) Endemic, not con- 

 sidered. 



Dr. Gill said the freshwater fishes of the 

 Philippines were of little interest in the pres- 

 ent connection, most of them being Asiatic 

 and many of them widely distributed. They 

 show no relationship with Australian forms. 



The 434th meeting was held November 16, 

 1907, President Stejneger in the chair. The 

 evening was taken up with an account by Dr. 

 B. W. Evermann, of " Freshwater Mussels and 

 the Pearl Button Industry " along the Missis- 

 sippi River, illustrated with specimens of 

 shells, buttons, pearls, etc. 



Wilfred H. Osgood, 

 Recording Secretary pro tern 



