1899.] NATURAL SCIENCES OF PHILADELPHIA. loO' 



Sekera ('96) observed specimens of earthworms of the speciety 

 Deiidrobcena ruhlda Nj. (^Allolobophora boeckii Eisen) frozen iu 

 blocks of ice in East Bohemia in December, 1886. When freed 

 from the ice they remained alive in the water for a week, when 

 they were preserved. This species is abundant in bottom land& 

 and along meadow brooks, and Sekera suggests that the worms 

 crawled out on the surface of the snow on a sunshiny winter's 

 day, and were imprisoned by the formation of an icy crust after 

 nightfall. 



Probably most naturalists have met Avith similar cases illustra- 

 ting the cold-resistiug power of earthworms. I add the following: 

 While at Woods Holl, Mass., in the summer of 1893, Mr. Joseph 

 Fay submitted to me for examination a large number of Enchy- 

 trseids taken from ice which had been cut during the previous 

 winter on his pond. Subsequently I received some of the ice con- 

 taining the living worms. This ice was porous and filled with air 

 or marsh gas vesicles like that sent to Dr. Leidy from Xew Jersey. 

 The Avorms became active in the ice water, but died during the 

 course of two days, the temperature of the water having risen ta 

 that of the air. This worm is probably identical with the Lum- 

 bricus glackdis of Leidy, and the " Lumbricoid " described by 

 Kraus ('86). It belongs to the genus Eiichytrceiis, but the species 

 is not stated in my notes, and the specimens are not just now avail- 

 able for examination. 



During the fall and winter of 1892-3, I kept a large number 

 of living annelids in my bedroom. Among these was an undeter- 

 mined species of Linnwdrilas, about thirty specimens of Avhich 

 lived in a tumbler of water. During some of the coldest nights 

 of the winter, when the temperature outside descended nearly to 

 zero, this tumbler remained standing on the sill of a window 

 which was opened for ventilation. In the morning the contents 

 would be a solid lump of ice Avith a tangled mass of the AA'orms em- 

 bedded in its centre. During the day the ice Avould thaAV and by 

 evening the worms would be actively waving their posterior ends. 

 This alternate freezing and thawing was repeated many times 

 and on one occasion the tumbler Avas placed in the open air and its 

 contents kept frozen for a w^eek At the close of the winter all 

 of the worms except three or four were still alive and normal. 



I know of no careful experiments on Oligochseta to determine 



