Sponge-fauna of Norway. 131 



nished with suitable apparatus for lightening' the labour of 

 hauling in the dredge. In this we lie calmly on the lake-like 

 surface of a narrow Fiord, where we are never more than 

 about a mile from land, and let down the dredge to find a 

 fauna unknown at Shetland, and approximating to that of the 

 deeper parts of the North-Atlantic Ocean. It fairly astounds 

 us at first, after what we have been accustomed to during 

 five-and-twenty years' dredging in our own shallow seas, to 

 drop the dredge over the boat-side and sec 400 fathoms of line 

 run out before a resting-place is found at the bottom, and this 

 so near to shore that, letting out as much line again, it is 

 actually possible to pull to shore from this great depth while 

 the dredge lies still where it was let go, to land and haul it 

 in from the rocks, and, if it does not catch (which it probably 

 will do as it mounts the precipice), there to bring it in. It 

 seems incredible until we have proved it, that in pulling over 

 those few hundred yards of smooth surface to the shore we 

 have passed over a precipice of more than 2000 feet, which 

 lies hidden by the calm water which ripples against our 

 bows." 



Present condition of the Sponges. — The specimens have 

 been all excellently preserved, some by drying, some by im- 

 mersion in spirits — the latter still retaining so many details 

 of their original histological character that I found it possible 

 to obtain considerable information with respect to the nature 

 of their soft parts. 



Mode of Preparation. — In preparing specimens for micro- 

 scopical examination I followed the ordinary methods for 

 obtaining the spicules in the free state ; but in cutting and 

 mounting " sections " I adopted the processes which have 

 hitherto, in this country at least, been confined to the exami- 

 nation of quite soft tissues. A piece was cut from the sponge 

 large enough to contain a representative of each of its different 

 tissues ; this was then soaked in distilled water till its con- 

 tained alcohol was as nearly as possible all extracted ; it was 

 then transferred to a strong solution of gum, in which it was 

 allowed to stand for an hour or so ; finally it was placed in 

 the well of a freezing-microtome and frozen in the usual way. 

 From the frozen specimen slices could be cut of any required 

 thinness, the razor, strange to say, passing through the soft 

 tissues and hard spicules with apparently equal case. 



The slices so obtained were variously treated : some stained, 

 and some not, were mounted in glycerine of various degrees 

 of strength ; others were treated first with absolute alcohol, 

 then with carbolic acid and turpentine and mounted in Canada 

 balsam. 



