[82] 



Ifrceb^water Spongee. 



By Henry Mills, Buffalo, N.Y. 



THE fresh-water sponges have, within the last ten years, been 

 brought into notice much more than in any decade since 

 their existence was known. The simple manner of 

 classification of Mr. Carter, of England, combined with the efforts 

 of a few individuals, have brought this branch of natural history 

 into prominence, equal to almost any subject within the range of 

 microscopical research. 



The first mention of the fresh-water sponges occurs as early as 

 1696, in the Almagesticu7n Botanicum, of Leonard Plukenet. 

 Linneus also mentions them in 1745. These were both 

 Botanists, and, like other Naturalists of that early day, considered 

 all sponges, whether marine or of fresh-water origin, to belong to 

 the vegetable kingdom. It was not till some advancement had 

 been made toward the perfection of the microscope, that their 

 character, in this respect, could be determined. They were 

 several times changed from animal to vegetable, and back again. 

 Ultimately, Grant, Carter, Bowerbank, Dujardin produced actual 

 proof of their animal organisation. Subsequent investigators 

 have verified their conclusions with regard to the fresh-water 

 species. It was for a long time unknown what effect running, or 

 still-water, had on their specific character. Those found in still- 

 water were called spongia lacustris^ and those found in running- 

 water spongia fiuviatilis. Subsequent observers, however, have 

 learned that both species (the only two known at that time) grow 

 indifferently in still and in running- water. In 181 6, Lamarck 

 introduced the term Spo?igilla for the fresh-water sponges ; which 

 term is now only used for one genus in Mr. Carter's classification, 

 and, in that case, without reference to its etymological significance. 



The vital organs of all sponges are supposed to be of the 

 same character. They are too minute to be observed and 

 defined, except by the most skilful observers, supplied with the 

 best appliances, and under the most favourable conditions. Yet, 

 \\\^ flagellate infusoria, which are the living factors of the sponge. 



