440 REPORT — 1856. 



appearance, and the inhalant pores were distinctly visible by the aid of a 

 2-inch lens. I removed these specimens from the water and placed them in 

 a saucer; in tlie course of a few minutes the surface of the sponges lost the 

 smooth distended appearance, the pores were scarcely distinguishable by the 

 aid of the same lens, and the surface became full of corrugations. The 

 oscula gradually contracted at about a line or half a line within the outer 

 margin, and this slow contraction continued in action until the openings were 

 completely closed, and a cup-shaped depression only remained to indicate 

 the large orifices which but 10 or 15 minutes previously were steadily pouring 

 forth the ex-current streams. The thin sharp membranous edges of the 

 osculum shrunk into a fleshy obtuse margin to the basin-shaped depression 

 of these organs in their closed state. 



I let them remain without water from half-past 9 o'clock in the morn- 

 ing until half-past 1 p.m., and then replaced them in the saucer with 

 a few fronds of green fuci, and gave them fresh sea-water. In 5 or 6 

 minutes there was a manifest expansion of the oscula, and they continued 

 gradually to open ; the obtuse margins became thin, sharp, and slightly pro- 

 jecting, and the currents were poured forth vigorously and continuously 

 from each osculum. I triturated a little crude indigo in sea-water, and let 

 it glide from the small palette knife over those portions of the sponges where 

 there were no oscula ; the molecules of indigo were immediately drawn 

 forcibly down to the surface, and were retained there. I then dropped in a 

 similar manner a few drops of the water laden Avith indigo, immediately 

 over the oscula ; a few molecules remained very close to the margin of the 

 osculum, but the remainder were driven off by the powerful jet of water 

 issuing from the osculum, and were speedily dispersed and mixed with the 

 surrounding fluid. By these experiments the in-current and ex-current actions 

 were rendered strikingly apparent, and it was evident that even in the imme- 

 diate vicinity of the oscula the in- current action was in full operation. At 

 a quarter past 3 o'clock the ex-current action had entirely ceased in one 

 of the four specimens, and was very languidly continued in the others, but 

 the oscula were still fully expanded ; before an hour had elapsed, the ex- 

 current action had apparently ceased in all the specimens ; the smaller oscula 

 were closed, but the larger ones were contracted to the extent of about half 

 their greatest amount of expansion. I drained the water from these sponges 

 at half-past 11 p.m., and at 10 o'clock the next morning, June 4, I filled up 

 the saucer with fresh sea-water, but I did not detect them in action during 

 the remainder of the day. At half-past ] 1 of the 4th the water was again 

 drained from them. 



June 5th. — At aquarter past9 a.m. I put fresh water to the same group of 

 Hal. caruncula ; about five minutes after the oscula were slowly opened, and 

 the ejection of the water from one of the small oscula near the middle part 

 of the largest sponge, commenced at first slowly, and then, after the lapse 

 of a iew minutes, with such force as to produce a continued elevation of the 

 surface of the water immediately above it, about a i or f of an inch above 

 the osculum. During this action of the smaller and more simple osculum 

 near the middle of the sponge, two large compound oscula, each consisting 

 of three or four orifices, situated in depressions near each end of the sponge, 

 were languidly pouring forth streams of water. Three quarters of an hour 

 after the commencement of the projection of the ex-current streams they 

 became still more languid in their action, and at the end of an hour they 

 entirely ceased ; the oscula in each of the groups near the ends of the sponge 

 were entirely closed, and the small one, near the middle of the sponge in 

 which the action had been the most forcible, alone remained partly open. 



