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them to fix themselves to some object. Spawning-time is in 

 summer. 



The geographical diffusion of the oyster is from 60 north 

 latitude to the tropics and the southern hemisphere. On 

 European coasts the oyster is the object of extensive fishery, 

 and it is largely cultivated in special oyster parks, for it is 

 not only an article of luxury, but even, especially in England 

 and America, a national food. The ancients also cultivated oysters 

 artificially. A century before Christ, according to Pliny, one 

 Sergius Grata was the first to make an oyster-park on a large 

 scale. The Romans of the Imperial age, on whose tables the 

 oyster was never missing, considered those the best that came 

 from Lake Lucrine, near Bajae. At Brindisi oysters were also 

 largely cultivated as at Taranto now. In the middle-ages they 

 were cultivated in England and Denmark. Now the principal 

 oyster-parks are on the Atlantic coast (Arcachon, Ostend), and 

 in the Adriatic. They are large stone-beds connected with the 

 sea by sluices, and frequently cleansed. The oysters are sowed 

 in these places and carefully tended till sufficiently fattened 

 for the market. Natural oyster-banks, for instance in the shallow 

 water of the coast of Holstein, yield a large supply. 



Tin* Sea-Squirts (Tuaiicata). 



We stand before a tank containing a curious picture of still- 

 life. Groups of white , half-transparent double-tubes , among 

 which are scattered some rough lumps that look as if made of 

 white glass or of wrinkled brown leather, are seen together with 

 splendid red things shaped like a sack with funnel-like openings 

 at the side and upper end. In one place lie lumps like greenish 

 jelly, and the sides of the tank are covered with a varicoloured 

 crust of starry pattern all strange forms of which the inhabitant 

 of the inland is entirely ignorant. These creatures hardly be- 

 tray their inner life, and it is only when we attentively observe 

 them that we see an occasional opening and shutting of the above- 

 mentioned funnels. 



This group, which resembles a bed of wonderful plants, is 

 a riddle to all who have not examined the organisation and habits 

 of the low animal forms comprised within it. Thus it is ne- 

 cessary to mention at least the most important facts relating 

 to the structure and development of these animals; all the more 

 because lately the Tunicata have played a great part in the 

 scientific discussion as to the origin of the vertebrate animals, 

 including man. 



