444 REPORT — 185C. 



and poured fresh sea-water slowly over the sponge, and positioned it again 

 for observation, and found that it was again in full action, having the three 

 oscula distended to the fullest extent of their capability. At half-past 4; 

 when I returned, they were perfectly quiescent, and the oscula had resumed 

 the appearance I have described above, with the very minute orifice in the 

 centre. I left them in that condition, and at 7 o'clock examined them again, 

 when I found them still quiescent ; but one of the two large groups of oscula 

 and the new one were entirely closed, while the other osculum at the largest 

 end of the sponge had opened to the extent of about one-third of its diameter, 

 and the membrane presented the appearance of a series of lines or corrugations 

 radiating from the centre to the circumference. I have since frequently 

 observed the same appearance when the oscula have been in a half-closed 

 condition. 



I observed today that three new oscula had been opened about midway 

 between the large group at the largest end of the sponge and the base of 

 the sponge ; these new organs entered upon their function with as much vigour 

 as the older ones, ejecting their streams with an equal degree of force. The 

 new osculum, formerly described as having been opened beneath the central 

 osculum, was increased in diameter; and the central one, formerly so energetic 

 in its action, remained completely closed. 



June 11, 12, and 13. — I continued to watch closely the action of this 

 interesting and active specimen. It continued to exhibit results very similar 

 to those already recorded. The three new oscula beneath the group at the 

 large end increased somewhat in diameter and acted with much force. The 

 central osculum, up to June 13, continued completely closed, and not the 

 slightest indication of its former existence could be discerned. Considerable 

 alteration had also taken place in the two large groups of oscula. At an 

 early period of my observations I sketched each of these groups carefully, 

 that I might be under no subsequent mistake regarding them ; and I was 

 induced to do so from having observed that even during the same day the 

 oscula in the same group varied in the relative degree of their diameter when 

 in full action ; and I have since frequently observed that sometimes the whole 

 were fully expanded and in vigorous action, while at other times the largest 

 osculum of the group would be very active, while the lesser ones were par- 

 tially closed and very languidly in action ; thus while from the large one the 

 molecules were ejected with great force and rapidity, those from the minor 

 ones seemed to float gently from their orifices until they came under the 

 influence of the forcible stream flowing from the large and active osculum. 



Some of the smaller oscula in each group have become apparently perma- 

 nently closed, while others have assumed greater dimensions : thus the confi- 

 guration of each of these large groups had become greatly modified, and the 

 sketch of them in their former condition was anything but a faithful portrait 

 of their present appearance. 



These variations in the position and diameter of the oscula are very inter- 

 esting, but are not so surprising as they may appear at the first blush. If we 

 examine the surface of the sponge in its most distended condition while in 

 full action, we see that immediately beneath the dermal membrane there is 

 a complicated system of large ex-current canals, inosculating with each other 

 in every possible direction, and forming a wide but irregular cloacal network. 

 At any point therefore in the course of these canals oscula may be generated 

 in accordance with the necessities of the animal, and new ones having been 

 thus generated, a portion of the older organs becomes more or less useless, 

 and during the cessation of action their membranous lip becomes firmly and 

 permanently closed. 



