SPONGES OR PORIFERA 
wi! PONGES are animals. The ordinary bath sponge is only the 
horny skeleton which in life was encased by living cells. In 
every living sponge, water is drawn in through numerous small open- 
ings, and thrown out through large ones. This water passes through 
the intricate channels of the sponge which are lined with thousands 
of minute cells, each provided with a collar, and a thread-like lash, 
which serves to capture and engulf the minute animals and plants 
that are drawn in with the water. In some sponges the skeleton is 
calcareous, and is composed of a vast number of curiously shaped 
spicules. In others it is mainly horny and fibrous as in commercial 
sponges, while in some, such as the Venus basket of the China 
Sea, it is glassy. The eggs develop within the sponge itself and 
are usually cast out as minute spherical or oblong larvee covered 
with cilia which enable the little creatures to swim rapidly through 
the water. In a few hours or days, however, they settle to the bot- 
tom and soon grow into sponges. Sponges of the same species often 
vary greatly in form, in accordance with the situation in which they 
grow, and they possess so lttle individuality that two sponges 
growing side by side will often fuse into one large mass. Sponges 
may also be cut into pieces, and each piece will grow into a perfect 
sponge. Good accounts of our American sponges are given by 
Hyatt, Memoirs of the Boston Society of Natural History, 1875 and 
1877, and Lambe, Transactions of the Royal Society of Canada, 
1892-94, 1896, 1900. 
COMMERCIAL SPONGES 
Our commercial sponges are found living only in the warmer 
seas, such as the waters of Florida, the West Indies, the Red Sea 
and Mediterranean. The sponges from Florida and the West 
Indies are inferior to those of the old world. There are many va- 
rieties of the commercial sponge but they all belong to the genus 
Spongia and have a skeleton made up of tough, closely meshed, horny 
