138 TROCEEDINGS OF THE ACADEMY OF [1899.. 



burrowing iDto the earth below the frost h'ne. Yet every one- 

 knows that after a warm rain in winter vast numbers of our com- 

 mon genera are often left dead on the surface of the ground to- 

 become the food of fowls, crows and other birds. A few warm 

 days will start earth-worms into conspicuous activity, and many 

 species retire beneath the surface only just so far as the actual 

 freezing of the soil compels them. Our common Enchytrseidse are 

 often found in clods of earth which are more or less completely 

 frozen, or in the interior of frozen logs amid crystals of ice. This 

 capacity of Oligochssta, and especially of the Enchytrffiidse, to resist 

 cold is now well known. Zoological literature contains the follow- 

 ing cases: Leidy ('84) describes some small worms (which he 

 refers to Lumbriculus, but later ('85) describes as Liimbricus 

 glacialis, which is an Enchytr?eid) found frozen in a block of- ice 

 taken from a mill-pond in Delaware County, Pa. With them Avere 

 associated Rotifer vulgaris and some immature Anguillulse. Later 

 some similar worms were received in a block of ice harvested from 

 a pond near Moorestown, N. J., nearly a year before. This ice 

 was filled with air bubbles and water drops in which the worms 

 could be seen. On the ice being melted, the worms were liberated 

 in an active condition and moved about in the water, but died 

 as the latter became warmed. Dr. Leidy supposed that they were 

 not actually frozen while imprisoned in the ice. He describes them 

 under the name of Lumbricus glacialis ('85). 



Kraus ('86) states that a small white worm was abundant in the 

 ice supplied to the town of Salina, Kaus. , during the summer of 

 1885. As the ice melted they became somewhat active, but died 

 when the temperature of the water reached 60° F. The same 

 species was found living in the mud at the bottom of stagnant 

 pools. Its presence in the ice is accounted for by the water 

 having frozen to the bottom in the ponds from which the ice had 

 been taken. 



Reecker ('96) found a living earthworm in natural ice on July 

 16. It was moving about in a cleft in the centre of a piece of ice. 

 The cleft communicated by a minute opening with the exterior. 

 He supposed that in February or March, during a thaw, the worm 

 had crawled between two blocks of ice which subsequently were 

 frozen together. This worm, which was identified as Lumbricus 

 rubellus, remained alive in the water until killed for preservation. 



