32 



through the same process, increasing the gelatinous mass, they 

 build up their future home, which is permanentl}- fixed. This 

 low organised gelatinous substance is called the amoeba ; in its 

 young state this mass is sometimes termed "proteus" from its 

 remarkable power of changing its form and place. Dr. Carpenter 

 in his " Principles of Physiology" gives us a very good diagram ; 

 and then he proceeds to say "This movement is accomplished 

 by the continual changes of form that take place in its body, the 

 typical figure of which may be termed globular, but which may 

 assume almost any shape whatever. The change of form seems 

 due rather to actions taking place in the interior of the cell 

 than to any irritability of the cell wall ; for if the movements 

 of an amoeba be attentively watched the extension of the 

 gelatinous body in any particular direction (so as to form one of 

 the digitate prolongations) will be seen to be preceded by the 

 setting of a current of the moving molecules within the cell in 

 that direction, to which current the protrusion of the cell wall is 

 really due. A continuation of the same current distends the 

 prolongation, and the whole mass of the body is gradually 

 carried onwards (so to speak) into it, so that its place in the field 

 of the microscope is slowly changed." But this movement ceases 

 with the growth of the sponge. From its simple gelatinous 

 constitution a framework of fibrous tissue is next constructed 

 to support the amoebic or sarcode matter (for this substance is 

 one and the same), and constitutes a huge colony of living 

 atoms, each with an independent existence, but all uniting in 

 the construction of their common home. Sponges, therefore, 

 as we have observed, increase by spores and by gemmiperous 

 reproduction, that is, new cells or buds protrude from the sides 

 of the parent cells which at length separate as perfect animalcules. 

 I may here mention that sponges have a great tenacity of life, 

 as a natural result of their organisation, and the sponge fisher- 

 men have availed themselves of the fact that a piece of sponge 

 may be cut up without destroying its vitality, so they now 

 propagate sponges in general, but especial attention is paid to 

 the cultivation of the more valuable species, and thus another 

 branch is added to our social industries. 



The range of the living spongidaa extends almost everywhere, 

 both in fresh and salt water, but the Mediterranean and the 

 tropics more especially supply our markets. Great numbers are 

 sent from the Bahamas ; these are however coarse. The finest 

 come from Turkey, particularly from Smyrna. The method of 

 preparing them for commerce is simply by squeezing out the 

 amoebic or sarcode matter, then washing them and allowing 

 them to dry and sweeten under the sun on the dry sandy shores, 

 which fully accounts for the quantity of minute sandy particles 

 found in all new sponges. 



(Some living sponges and a fine series of dried ones were 

 exhibited on the table. An oyster supposed to be over fifteen 

 years old was also shown ; its surface was partially coated with 



