308 SUMMARY OF CURRENT RESEARCHES RELATING TO 



less growth at first, then spicules were seen, in slightly fasciculated 

 lines, attached to the glass and reaching upward, then spreading out 

 fan-like and branching. Those were, of course, covered with sarcode, 

 nearly transparent at first, and through the filmy surface pores and 

 osteoles could be detected with a pocket lens. The latter were sur- 

 mounted by the so-called " chimneys " or cone-shaped extensions of 

 tho dermal film; and through the apertures at their summits effete 

 particles could almost constantly be seen, puffed out, as if thrown from 

 a volcano, and then blown off by the wind. 



These products of single gemmules did not, as time passed on, 

 greatly increase in size — possibly, because of a deficient nutriment in the 

 unchanged water of the jar — but, crawling upward along the glass to an 

 average height of an inch or less, left the naked spicules in place behind 

 them as so many ladders or stepping-stones of their dead selves by which 

 they had reached to higher things. Near the summit, one or more new 

 gemmules would sometimes be formed, after which the mother mass 

 entirely disappeared. 



So much for the amount of growth from single gemmules. Where, 

 however, they were thickly sown, or germinated in situ upon the stone, 

 so that the contents of several could mingle and flow together, tho 

 resultant sponge was very much larger. The mass, if it may be so 

 called, covered, at its best, nearly one-third the surface of the jar ; while 

 those gemmules remaining upon the stone and amongst the spicules 

 of the old sponge continued to germinate, to form abundant sarcode 

 and spicules, and, at least in one place, to throw out a long unsupported 

 branch or finger-like process that ultimately reached a length of two or 

 three inches. 



Of course it was impossible to bring the higher powers of a com- 

 pound Microscope to bear upon a sponge growing under such circum- 

 stances. A strong Coddington lens was the best that could be applied 

 to this work ; but a very fair share of success was obtained by the device 

 of scattering small squares of mica among the growing gemmules, 

 which, when covered by the young sponge, could be moved to the stage 

 of the instrument, covered with water in a compressorium and examined 

 comparatively at leisure. It was a perpetual cause of astonishment to 

 see so large a production of silicious spicules from a single gallon of 

 water, in which the chemist would probably have failed to find any 

 such constituent. It is worthy of consideration however, whether such 

 silica as composed the older spicules may not, at least when under 

 the influence of the growth force of the younger sponges, be to some 

 extent soluble. 



For the determination of species the author gives a few general 

 directions, which however he thinks will be soon modified to suit the 

 taste or ingenuity of the worker. It is assumed that the investigator 

 has already noted the general appearance of the sponge in hand ; its 

 colour, size, compactness, whether simply encrusting, or cushion-like, 

 sending out finger-like processes, &c. These indications may help an 

 experienced collector to a guess ; but there are very few species that 

 even such a one could name, with any confidence, before he had made 

 and examined microscopical preparations of the same. 



A stand, supporting a dozen or more test-tubes, say 3/4 in. in diameter 

 by 1] in. in depth ; a dropping-bottle containing nitric acid, and the usual 

 material and apparatus for mounting in balsam are all the appliances 



