446 REPORT — 1856. 



having increased in weight one-nineteenth, or rather more than 5 per cent. 

 The difference between the first and second weighing, under similar circum- 

 stances, therefore amounted to 16 grains. It had thus lost one-ninth of its 

 original weight. 



I continued to observe daily the condition of this sponge which had previ- 

 ously afforded me such satisfactory results. It exhibited very little difference 

 in appearance until the 15th of July, when tt became somewhat paler in 

 colour; after being an hour out of the water it weighed 121 grains. I con- 

 tinued to examine it frequently from the 15th to the 20th of July, and I found 

 that the paleness that I had noticed on the former date, was occasioned by 

 a gradual dissolution or change of the dermal membrane, the remains of 

 which hung about the sponge in the form of small flocculent fragments. 



This dissolution or change of the dermal membrane produced a remarkable 

 alteration of its external features. Beneath the old dermal membrane, as I 

 before stated, there were several large superficial canals which meandered 

 irregularly over nearly every part of the sponge, with which the oscula were 

 always connected ; but after the dissolution of the membrane, the whole 

 of these closed canals were uncovered, and became simply a series of deeply 

 indented channels on the exposed surface, and no membranous oscula were 

 any longer apparent; but in the places formerly occupied by these, there 

 remained a series of large, irregular orifices only, without any membranous 

 veil whatever that was apparent. Under these circumstances, the sponge 

 presented a much more rugged and attenuated appearance than it had pre- 

 viously exhibited, and I accordingly weighed it again, under precisely the 

 former circumstances, and was surprised to find that the weight was 121 

 grains, being precisely the same as when weighed five days previously. 



From the 1st of July to the 20th I examined this sponge frequently, and 

 often endeavoured to excite it to ex-current action by pouring water over it, 

 but without success. On the 21st of July I omitted to replace it in the water 

 at night, and in the morning I found it was dead, giving forth a peculiar 

 odour that always accompanies the death of the sponge. 



Adhesion of Species. 



It has long been known to naturalists, through the valuable communi- 

 cations of Dr. Grant in the Edinburgli Philosophical Journal, vol. xiv. 

 p. 115, that individuals of the same species of sponge growing near each other, 

 united and became as one sponge, when by their natural extension they came 

 in contact ; and that individuals of different species under similar circum- 

 stances, however closely they might embrace each other, never became 

 organically united. I have frequently seen these facts verified in their natural 

 localities at Tenby, and under other circumstances. I determined therefore 

 to endeavour to ascertain, if possible, the phaenomena that were exhibited 

 under such occasions of coalescence. 



On the 4th of June, at 3 p.m., I placed nine small specimens of Hyme' 

 niacidon caruncula in a saucer-full of salt-water with a few green fuci in it, 

 and I arranged the sponges gently in contact with each other. On 

 examining them at 11 o'clock a.m. on the 5th of June, I found that five of 

 these specimens in which the contact had been complete, were firmly 

 cemented together. Two of them were one and a half inch in length, and 

 three-fourths of an inch in breadth, and the others about half that size; but 

 so strong was the adhesion, that the largest four, full of water, were readily 

 sustained out of the water by the smallest of the united group. Twenty hours 

 therefore had sufficed to unite them firmly. 



At 3 o'clock P.M. of the 5th of June, 1 placed several specimens of the 



