1885.] NEW-YORK MICROSCOPICAL SOCIETY. 121 



sea-bottom they are taken to the shore and placed where the 

 water can get access to them and wash away the protoplasmic 

 matter. They are still further cleansed by the use of chloride 

 of lime, by exposure to the sun, and by washing in water, until 

 nothing but the keratose is left. They are then dried and 

 packed and sent to the market. The closeness of the packing 

 greatly changes their appearance ; but, when freed from com- 

 pression and soaked in water, they regain nearly their original 

 size and shape. It is to the ease with which it absorbs and, 

 under pressure, gives up, water, that the fibrous sponge owes its 

 usefulness ; and this property depends on the flexibleness and 

 elasticity of the keratose fibres, as well as on the abundance of 

 the canals which ramify among them. 



In the quality of the keratose, sponges differ according to 

 their habitat. Those occurring in United States waters are 

 coarse. The finest grow along the coasts of Syria and Greece. 

 These are detached from their beds with great care by the hands 

 of divers who go down from vessels specially designed for this 

 work. Among them is the famous Turkish cup-sponge, which 

 is highly valued on account of the silk-like fineness and softness 

 of its fibres. Its form gives it its name. A large specimen is 

 costly. Indeed, in former times it brought almost its weight in 

 gold. Sponges with coarse keratose fibre are less expensive, and 

 are collected with less care. Of medium quality and cost is the 

 '* woolly sponge," so called from its resemblance to sheep's wool. 

 It is soft, tough, and, for ordinary uses, good. 



The ordinary keratose sponges are not beautiful; they are 

 simply useful. The converse is true of the form called the 

 glass-sponge. This occurs sometimes in very deep waters. In 

 most cases its framework consists entirely of long and delicate 

 glass-like spicules. One species, called Venus's Flower-basket, 

 is shaped like a cornucopia, and grows sometimes to a length of 

 twelve or more inches. Its fibres are so interlaced with one 

 another as to form octagonal openings and present a sieve-like 

 aspect. Of other forms of glass-sponge, some are globular, some 

 oval. An abundance of fine intersecting fibres gives to these 

 also a beautiful lace-like appearance. From the base proceeds 

 a bundle of long glass-like threads by which the sponge is 

 anchored to the sea-bottom. 



The so-called boring-sponge, the enemy of the oyster, belongs 



