422 THE CANADIAN NATURALIST. [Yol. vii, 



second voyage of Kotzebuc, though fearfully laborious, gave 

 results that correspond most closely with the ''Challenger's".; 

 a fact iu scientific annals which has been lately dug out by Prof. 

 Prestwich, and by him brought to the notice of the lecturer, who 

 found his own conclusions — made in entire ignorance of those of 

 Lenz — thus singul irly confirmed. The conclusions to be drawn 

 from a study of these temperatures point towards a deep flow of 

 polar water towards the Equator, unrestricted, as regards the 

 Atlantic, towards the south, but limited in the direction of the 

 North Polar area, where there are two principal channels : the 

 one between Greenland and Iceland, the other between the Faroe 

 Islands and the 100-fathom line of North-west Europe, on which 

 platform the British Islands repose. This latter is the "Light- 

 ning" channel, the scene of the lecturer's first explorations, the 

 study of which led to his view of the existence of two opposite 

 flows in the great oceanic area, quite irrespective of any one 

 current. In this channel it was found that there was a super- 

 ficial warm stream and a deep cold stream ; and that within a 

 vertical space of 50 fathoms a most marked difi"erence of tem- 

 perature is suddenly encountered ; whilst, as regards horizontal 

 distance, temperatures of 29^^^ F. and 43^ F. have been ob- 

 tained at the same depth in places not 20 miles apart. These 

 facts mean that there are two distinct movements of water, just 

 as a striking difi"erence in the temperature of the atmosphere in- 

 dicates a change of wind. Hence, speaking with reference to 

 the "Li2;htning" channel, it is clear that water much colder than 

 the mean winter temperature of the latitude must have a nor- 

 therly, whilst water that is warmer must have a southerly source. 

 In accordance with this we find that most of the animals of the 

 cold area, such as the beautiful Comatula Esclirlchtii, belong 

 to the boreal fauna ; whilst British species, such as the common 

 Solaster pcipposa, which is dwarfed from the size of a plate to 

 that of a crown-piece, are much stunted. Yet the fauna is abun- 

 dant, as no temperature seems to prevent life, so long as sea- 

 water is liquid. Pressure, though enormous, will not afiect vital 

 functions ; since an animal, whose cavities contain air in aqueous 

 solution only, can contract and expand just as well with a pres- 

 sure of three tons to the square inch as it can on the surface. 

 Not but what change of pressure, brought on by sudden removal, 

 mi»ht produce some derangement. Neither temperature nor 

 pressure, then, being directly of supreme importance, it is the 



