. Fresh-water biology. Freshwater biology. 578 FRESH-WATER BIOLOGY difficult than that of any other group of rotifers; it has been con- fined mainly to specialists in this particular group. Many species of the Bdelloida possess a remarkable power of withstanding dry- ing. Philodina roseola is often found as Httle pink balls in the dry deposits in the bottoms of urns and eave-troughs. When this material is placed in water, the pink balls quickly swell, take the rotifer form, and continue their inter- rupted life activities where these were stopped. Many species may be ob- tained for study in th
. Fresh-water biology. Freshwater biology. 578 FRESH-WATER BIOLOGY difficult than that of any other group of rotifers; it has been con- fined mainly to specialists in this particular group. Many species of the Bdelloida possess a remarkable power of withstanding dry- ing. Philodina roseola is often found as Httle pink balls in the dry deposits in the bottoms of urns and eave-troughs. When this material is placed in water, the pink balls quickly swell, take the rotifer form, and continue their inter- rupted life activities where these were stopped. Many species may be ob- tained for study in the Uving condition from dried moss and other vegetation brought from a distance. No males are known in the Bdelloida. 26. The Seisonacea (Fig. 868) are ex- traordinary rotifers parasitic on marine Crustacea. Their relationships are un- certain, but, having two ovaries, they are usually placed near the Bdelloida. In the Seisonacea male and female are Since they are exclusively marine, these forms are omitted from the synoptic key. The studies thus far made of the rotifers of different regions seem to indicate that in general these animals may be said to be potentially cosmopohtan, any given species occurring wherever the conditions necessary to its existence occur. Whether any given rotifer shall be found in a given body of water depends mainly, not upon the locality of this body of water, but upon the precise conditions there found. Studies on the rotifers of Europe, Asia, Africa, America, and Australia show, not different faunas in these regions, but the same common rotifers found everywhere, with merely a new form here and there, and it is an extraordinary fact that when a new rotifer is described from Africa or Australia, its next occurrence is often recorded from Europe or America. In stagnant swamps all over the world appear to be found the char-. FlG. 868. Seison annulatus Claus, female, (After Glaus.) similar and of equal Please note that these images are extracted
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