Maech 4, 1910] 



SCIENCE 



359 



other research work is in progress and addi- 

 tional publications will probably appear during 

 the coming year. 



The relationship of the academy to the public 

 during the past year may be tabulated as follows : 



Annual attendance to museum 300,000 



Annual attendance to public lectures .... 4,000 



Attendance at the 12 lessons in the first 

 teachers' course (28 teachers X 12 les- 

 sons) 336 



Attendance at the 6 lessons in the young 



people's course (6 lessons X 122 pupils) 732 



School children addressed by delegates to 



young people's course 50,000 



Children addressed at schools by Mr. F. 



C. Baker, of museiun staff 11,303 



Loan collections from museum ( 129 school 



rooms averaging 50 pupils) 6,450 



Total 372,821 



Wallace W. Atwood, 



Secretary 



THE BIOLOGICAL SOCIETY OF WASHINGTON 



The 365th meeting of tlie society was held Jan- 

 uary 22, in the main hall of George Washington 

 University, with President T. S. Palmer in the 

 chair and about a hundred persons present. 



The following communication was presented: 



Fluctuation of Animal Population in the 'North- 

 west : Ernest Thompson Seton. 

 The speaker described conditions as to animal 

 life observed during his long residence in Mani- 

 toba, instancing the marked changes in numbers 

 of indigenous mammals to be seen from year to 

 year. Shrews, muskrats, rabbits, lynxes, wolves 

 and other animals were subject to great fluctua- 

 tion in numbers. In some cases the causes of 

 change were partially known, but in others they 

 could not be explained. Mr. Seton exhibited 

 charts showing diagrammatically the yearly col- 

 lections of skins of fur-bearing animals by the 

 Hudson's Bay Company. These showed in a clear 

 way the enormous fluctuations in the fur returns 

 during the years from 1751 to 1891. 



An interesting discussion followed. J). E. Lantz 

 called attention to the fact that the prevailing 

 fashions in fur garments often have much to do 

 with the numbers of skins collected. Dr. Palmer 

 showed how the prevailing fashion influences the 

 sale of bird skins and feathers, and how it has 

 often disastrously afifected the bird population of 

 certain districts and nearly exterminated a species. 



Vernon Bailey told of the occasional vast in- 

 creases in numbers of small mammals, referring 

 especially to the field mice (Microtus montana) , 

 which in 1907 and 1908 did enormous injury to 

 crops in the Carson and other valleys of the west. 

 In this instance predatory mammals and birds 

 assisted by unfavorable weather conditions were 

 recognized factors in removing the plague of mice. 



Dr. A. D. Hopkins told of the enormous fiuctua- 

 tions in numbers of certain insects, well-known 

 illustrations being afi'orded by plagues of locusts 

 and criclcets and the periodical appearance of 

 cicadas. He gave as a particular illustration the 

 northward migration of the southern pine bark 

 beetle [Dendroetonus frontalis), which in 1891 

 and 1892 culminated in the destruction of a large 

 part of the pine and spruce timber on about 75,000 

 square miles of the forests of Pennsylvania, Mary- 

 land, Virginia and West Virginia. Being a south- 

 ern species, it could not withstand the extreme 

 cold of the winter of 1892-3, and the species 

 perished throughout the region named, while 

 native insects were not killed. In this case, the 

 sudden change in numbers was well understood. 



Dr. Barton W. Evermann called attention to the 

 fact that there is a well-marked periodicity in the 

 run of certain species of fishes. This is notably 

 the case with the hujnpback salmon in the rivers 

 of the Puget Sound region and the sockeye salmon 

 in the Fraser River. A large run of humpbacl'is 

 takes place in the odd years (as in 1905, 1907, 

 etc.) and a much smaller run in the even years. 

 A big run of sockeyes occurs every fourth year, 

 the run in each of the three other years of the 

 cycle being smaller. The reasons for this period- 

 icity are not fully understood. These species of 

 salmon, like all salmon on our west coast, spawn 

 only once, then die, even before the eggs hatch; 

 so that no Pacific salmon ever saw any of its 

 children or either of its parents. The life of the 

 sockeye salmon is probably four years. The eggs 

 laid in the Fraser River produce fish which come 

 back four years later to spawn. If the spawning 

 conditions in some year of the remote past were 

 exceptionally favorable and an unusual number of 

 young fish hatched, every fourth year thereafter 

 ought to be a big year for that species. It is 

 believed that an explanation like this is the cor- 

 rect one. 



The discussion was closed by Dr. Palmer and 

 Mr. Seton, and the society then adjourned. 



D. E. Lantz, 

 Recording Secretary 



