Plumatella javanica.
The following forms flourish mainly during the "rains":—
Spongilla lacustris subsp. reticulata.
Trochospongilla latouchiana.
Trochospongilla phillottiana.
Stolella indica.
The following flourish throughout the year:—
Spongilla proliferens.
Hislopia lacustris.
It is particularly interesting to note that three of the species that flourish in the mild winter of Bengal, namely Hydra vulgaris, Plumatella emarginata, and P. fruticosa, are identical with species that in Europe perish in winter. There is evidence, moreover, that the statoblasts of the genus to which two of them belong burst more readily, and thus give rise to new colonies, after being subjected to a considerable amount of cold. In Bengal they only burst after being subjected to the heat of the hot weather. Does extreme heat have a similar effect on aquatic organisms as extreme cold? There is some evidence that it has.