HARDWICKE'S SCIENCE-GOSSIP. 



157 



known objects, attached to the spines, called 

 pedicellaria, are also both elegant and instructive 

 microscopical objects. The construction of the test 

 or shell of the Sea-Urchin, with its hundreds of 

 plates that grow along their margin from the young 

 to the adult condition, five rows of which are per- 

 forated by thousands of minute holes (the ambulacral 

 plates), the separate plates at the summit surround- 

 ing the anal orifice, through which ;the sea-water 



being forced into them, the Sea-Urchin can warp 

 itself along the sea-bottom. The fossil forms found 

 even in the primary rocks tell us how long both 

 the mechanism of the test and that of the water- 

 vascular system has been in existence. 



A transverse section of one of these common 

 spines, if properly and thinly cut, forms a most 

 beautiful microscopic object, as fig. 101 shows. The 

 sketch here given as an illustration has been copied 



Fig. 101. Magnified section of spine of Echinus, trom a pen-and-ink sketch by G. R. Connor, Esq. 



is filtered and allowed to pass into the internal 

 water-vascular system — all these arc features 

 whose careful study will train the young student to 

 habits of accurate observation. Nothing can ex- 

 ceed the marvellous economy which provides for 

 the locomotion of the Sea- Urchins. The "water- 

 vascular " system, as it is called, gives out pipes that 

 run in front of each row of ambulacral plates, and 

 these, in their turn, branch off into thousands more- 

 Each of the latter penetrates the minute perfora- 

 tions to be seen in the empty shell when it is held 

 up to the light, and extends even beyond the spines. 

 Each has a sucker at the end ; so that by means of 

 these pipes, which are lengthened at will by water 



by Dallastype (the process to which we referred in 

 the last number of Gossip), and printed from a 

 drawing from the microscope by R, Connor, Esq. 

 Thus seen, the transverse section resembles knitted 

 anti-macassars, only that the latter rarely equal it 

 in beauty. Perhaps some of our fair readers may 

 take a hint from the " pattern " here given. 



J. E. Taylor, 



Blue Titmouse. — A friend of mine saw (last 

 spring) a little blue tit with a caterpillar in its 

 mouth, endeavouring to feed one of its young ones, 

 which had fallen from the nest, and was quite dead. 

 — ir. H. Warner, Kingston. 



