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HARDWICKE'S SCIENCE-GOSSIP. 



MICROSCOPY. 



Sponge Spicules. — There are two common 

 sponges to which I would direct attention as fur- 

 nishing interesting spicules. The one is the common 

 freshwater sponge, Spongilla jluciatilis, in which are 



Fig. 159. Spicules of Spongilla flubiatilis x 300. 



spicules of two forms, — one with two discs like ser- 

 rated wheels united by an axle, the other slightly 

 curved,'pointed at each end,and rough on the surface. 

 These are siliceous spicules, and may be obtained by 

 the use of nitric acid. The other is a marine sponge, 

 but the spicules are calcareous, and wonld be de- 

 stroyed by the use of nitric acid. In this case 

 liquor potassa; must be employed to obtain the 



Fig. 160. Spicules of Grantia compresta. 



spicules, which are also of two forms ; one being 

 tri-radiate and the other club-shaped at one end 

 and pointed at the other. The sponge is very 

 small and white, and may be found attached to sea. 



weeds. It is called Grantia compressa. These 

 spicules should have a place in every cabinet. — C. 



Scale of Loach {Colitis barbatula). — We give 

 herewith a figure of the scale of this pretty little 

 fish, which has been obtained and placed at our 

 disposal by our engraver, Mr. George W. Ruffle. 



Fig. 161. Scale of Loach. 



Paste Eels. — As it may not have fallen to the 

 lot of many of the readers of Science-Gossip to be 

 present at the birth (?) of a paste eel, I will relate 

 a case, leaving it to the learned to decide whether 

 or not a paste eel is bom at all. Having selected 

 a pregnant eel in which the young were slightly in 

 motion, I placed it on the stage of my microscope, 

 so as conveniently to observe, from time to time, 

 auy changes that might take place in their develop- 

 ment. The first thing I noticed was one of the 

 young passing slowly up the body of the parent ; — 

 subsequently another, then another, until the whole 

 brood were in motion. But that which surprised 

 me most was that they had free course backwards 

 and forwards, from the extreme tip of the tail to 

 the head of the parent ; and this action continued 

 for hours, the young, as time went on, increasing 

 in vigour and activity. As the rapidity of their 

 movements increased, the parent eel began to exhi- 

 bit evident signs of distress, her violent contortions 

 indicating such intense agony that I was greatly 

 pained in seeing her. But the young brood had 

 no such compassionate feelings ; they continued 

 rushing to and fro with redoubled energy, seeking 

 a way of exit ; and this at last they found in a way 

 I little anticipated, — the rupture of the parent's 

 body, from whence ten young escaped to live on 

 paste awhile, enjoy life, and then pass through a 

 like ordeal. But what became of the old lady ? 

 All that was left of the mother was her head, 

 gizzard, and an almost invisible fragment of her 

 skin ; the young cannibals had devoured all else of 

 their parent. She had been long defunct; and the 

 violent contortions that had so excited my sym- 

 pathy were caused by the frantic efforts of the 

 young in endeavouring to escape from their prison- 

 house. — A. Nicholson. 



