ANIMAL PRODUCTS 155 



and orange beneath ; those of C. tuber osa, white 

 outside and claret-coloured beneath ; and those of 

 Strombus gigas, yellow outside and pink beneath. 



The bath sponge supplies us with an indispensable 

 article for our toilet, but the substance as we use 

 it is only the skeleton of the living creature, from 

 which the gelatinous body (somewhat resembling 

 the white of an egg) which fills the porous interior 

 and surrounds the exterior, as well as the horny 

 fibres which add a further support to the skeleton, 

 have been removed. Of the many different kinds 

 of sponges numbering about 2,000 kinds, and of 

 which some 300 are to be found around the coasts 

 of the British Isles some are no larger than a 

 pin's head, and others grow to a height of several 

 feet. They vary also the one from the other in 

 regard to their shape, some resembling a cup in 

 form, others being spherical, others tubular, and 

 others assuming the formation of a branched tree. 

 During their life they are often prettily coloured, 

 and although in the majority of cases different 

 shades of yellow and brown are their predominating 

 hues, yet green, pale lilac, indigo, bright blue, 

 rosy red, black, and even white sponges are to be 

 found. 



The red coral, formerly so popular for manufac- 

 turing into necklaces, is another product for which 

 mankind is indebted to living animals ; the material 

 being the hard calcareous substance that tiny 

 marine polyps secrete around themselves as a means 

 of support, and for a habitation. Then, again, the 

 fossil remains of animalcules enter into the com- 



