250 APPENDIX. No. VII. 



ordinary has long been known. Otho F. Miiller froze indi- 

 viduals of Cyclops qiiadricornis in a glass vessel, and when 

 fully frozen continued the cold for four and twenty hours. 

 He then placed the vessel in a warm bath, and watched the 

 effect. For four and twenty hours the Crustacea which had 

 been frozen showed no signs of life ; the next morning, 

 however, to his surprise he found the greater part of them 

 restored to life and swimming about as before congelation. 

 It is a well-known fact also that the life of the eggs of Ostra- 

 coda and Cladocera can be maintained for many months, 

 when ponds have been completely dried up in the summer 

 months, or frozen to their very bottom in mid-winter. 



In the extremely cold winter of 1859 and 1860 I insti- 

 tuted some experiments for the purpose of finding how far 

 life could be maintained, under extraordinarily trying con- 

 ditions, among the lower orders of the Crustacea. The water 

 of the lake in Hardwicke Park, in the parish of Sedgefield, 

 had in the month of October been let off so as to drain 

 large mud-flats on the shelving sides, in order that the weeds, 

 exposed by this means to the influence of the frost during the 

 winter months, might be destroyed. The severest cold of 

 which we have record ensued for five weeks. From the 

 seventeenth day of December the mud-flats were continuously 

 frozen into a solid block, and the frost on Christmas Eve 

 reached five degrees below zero, Fahr. On the conclusion of 

 the frost a portion of this mud was procured, and, yet further 

 to test the vitality of the eggs embedded in it, the mud was 

 thoroughly dried. On March 11a small portion of the mud 

 was placed in a glass jar of water and exposed to a genial 

 temperature. A few days afterwards Daphnia rotunda, 

 Sida crystallina, Diaptomus castor, and Cyclops quadri- 

 cornis, together with some Rotifera, were swimming about 

 merrily in the vessel. 



It is no surprise therefore to us to meet with these minute 

 Crustacea in mid-winter in the Arctic Sea, though the fact is 

 of importance as bearing upon the supply of food existing 

 during the winter months for the Greenland whales. 



