S^ THE ANATOMY OF INVERTEBRATED ANIMALS. 



this sometimes contains only an oil-globule, at others cells, or 

 nuclei, and crystalline bodies. In the layer of protoplasm 



Fig 5 —Spha&rozoum punctaUim.—A, a mass of the natural size ; B, two of the oval 

 central sacs with the colored vesicles and spicula which lie iu the investing pro- 

 toplasm, magnified. 



Fig. Q.—Sphmrozoum ovodimare (after Haeckel), magnified. 



from which the pseudopodia proceed, celL^form bodies of a 

 bright-yellow color, which have been found to contain starch, 

 are usually developed,' and this layer also gives rise to a skele- 

 ton of a horny, or, more usually, silicious character, which 



1 Even after the death of the Eadiolarian, these yellow cells are said by Cien- 

 kowsky to thrive and multiply, and the possibility that they may be parasites 

 must be borne in mind. 



