1 86 Cincinnati Society of Natural History. 



ered with spines. It is in the statoblasts that we find the greatest 

 variety of spicules. 



As early as 1766 Linnaeus had observed that in the autumn 

 certain globular bodies were developed. Sponges were then con- 

 sidered plants. But in 1839 Meyen, in commenting upon the 

 globiili, said that they were "distinct from the sporangia of algae, 

 and similar to what are called the winter eggs of polyps." In 

 keeping with this idea these bodies have since been named stato- 

 blasts, and are commonly so called, although some authors prefer 

 the name "gemmule." Furtlier observation developed the fact 

 that these bodies germinate in water and reproduce the species. 



In general the statoblasts may be said to be about the size of 

 a mustard seed, varying in size and shape, but always approaching 

 a globular form. On one side is an opening connecting with the 

 soft matter of the interior. This soft matter is made up of a num- 

 ber of transparent sacs containing the germinal matter. The sacs 

 are inclosed in a delicate membrane, which is again covered by a 

 thicker chitinous coat. Outside of this is the wall or crust of the 

 statoblast. This crust is composed of air cells, in some species 

 readily distinguished, while in others the highest powers of the 

 microscope are required to resolve them. This structure causes 

 the statoblasts to float when detached from the sponge, and proba- 

 bly in some cases serves to scatter the species. Again the wall is 

 accompanied by or charged with siliceous spicules of various forms. 

 The statoblasts are usually to be found at the base of the sponge, 

 frequently attached to the object upon which it is growing, but 

 sometimes scattered through the skeleton. 



In addition to the spicules of the skeleton and statoblasts, there 

 is another kind known as " dermal" spicules. These are generally 

 more delicate than the skeleton spicules. 



In 1 88 1 Carter published his classification, based on the form 

 of the statoblast spicules. These characters are very constant ; 

 and as all the fresh-water sponges probably, and none of the ma- 

 rine come under the group Spongillina — that is, bearing reproduc- 

 tive organs called statoblasts — this classification, or some variation 

 of it, seems an especially good one. 



Young sponges may be found as early as June, but mature 

 specimens need only be sought late in the summer or in autumn. 

 They are readily detected by their bristly surface. The color and 

 shape are generally more or less influenced by the position in which 

 they grow. They may be found at the margins of rivers and lakes. 



