96 Mr. H.J. Carter on the Freshwater Sponges of Bombay. 
comes based on a mass of them, the lowermost of which merely 
consist of the refuse of those which have fulfilled the purpose for 
which they were originally destined*. 
Connected with the growth of Spongilla is also the following 
fact, which presented itself to me and which is interesting, inas- 
much as it seems to point out, that germs or full-developed cells 
of it abound in the water of the tanks, independently of those 
which exist imbedded in their natural structure: viz. one day I 
observed a few fresh straws floating together on the surface of 
the water of a tank which abounded with several species of Spon- 
gilla; they had been accidentally thrown there, but before they 
began to change colour from putrescence, and therefore but a 
few days after they had been in the water, a growth of Spongilla 
alba took place around each straw separately, which soon in- 
creased to the thickness of half an inch. I do not remember to 
have seen another instance of such rapid growth, and the fresh- 
ness of the straw proved this rapidity, for in this country it 
changes colour after a very few days’ immersion. 
Although I was perfectly aware that Spongilla might be unco- 
vered by water for many months in the year and still retain its 
vitality, yet I wished to see if this would be the case after the 
interval of more than a year. I therefore placed some portions, 
which I had kept for this purpose, in tanks supported on bits 
of cork, and others on stones from which they had been unde- 
tached ; but from some cause or other, whether from the partial 
putrescence which its dry fleshy substance subsequently under- 
went, or from this bemg present in a larger quantity in sponges 
taken out of the water in their living state and carefully pre- 
served, than in those exposed to the sun and winds on the dry 
rocks throughout the greater part of the year, or from both com- 
bined, the shrimps and crabs were attracted towards the former 
and devoured them with rapacity, while they left the latter un- 
touched ; so that I was at last compelled to enclose a portion in a 
gauze-wire case, which was kept 3 or 4 feet beneath the sur- 
face of the water for several months. This portion was fixed on a 
stone, in the position in which it had grown, and when the case 
was taken up it was found to have exceeded by many times its ori- 
ginal bulk, was covered with its natural pellicle, and in the active 
performance of all its vital functions. 
Colour.—This in all, excepting cinerea, appears to be yellow. 
* Dutrochet has noticed the fact, that in a piece of Spongilla which he 
kept in water for some months, and which contained seed-like bodies, all 
the soft parts died, became putrid, and dissolved away during the winter, 
and that in the following spring the fleshy substance became renewed.— 
Mémoires pour servir &l'Hist. Anat. et Physiol. des Végétaux et des Ani- 
maux, t. ii. p. 436. 
