450 REPORT — 1856. 



dantly, has been long well known, but what the effects of the exertion of 

 those functions were has been little noted by naturalists; and although, 

 by the almost universal consent of zoologists, they have been received as 

 animals, they have been denied the possession of stomach, intestines, and 

 almost of every organ that constitutes aniniality, while in truth nearly the 

 whole of the interior of the animal is one large stomachal cavity, furnished 

 abundantly with mucous membranes, if I may so term them, covered with a 

 coat of sarcode, analogous in every respect to the mucous lining of the 

 intestines of the higher animals, and which performs for the sponge precisely 

 those functions that the sarcode exerts, ivovnActinophrys jSW upwards, through 

 every gradation of animal existence, to man, and the rest of the most elabo- 

 rately constructed animals. This extraordinary substance, designated, in 

 Actinophrys Sol, sarcode by KoUiker, and in the higher animals known by 

 anatomists as the mucous lining of the intestines, is apparently an organ 

 of very much more importance in the process of digestion than has been 

 generally conceived. It is never deficient in any animal, from the lowest 

 to the highest. I have examined it from living specimens microscopically in 

 Acalepha, Actinia, Radiaria, Fishes, and in the Mouse and other small 

 quadrupeds ; and in all, it presents nearly the same appearance. It is semi- 

 transparent, has an uneven corrugated surface, and in every instance in which 

 I have observed it, abounds with solid and vesicular molecules of extraneous 

 matter in a semi- digested state. Generally speaking, of the vesicular mole- 

 cules, very few indeed are in a fully distended condition, and by far the 

 greater number present every degree of collapse that can well be imagined 

 during the dissolution of such bodies by digestion. 



In the Spongiadse there is every reason to believe that the imbibition of 

 the molecules by this substance is precisely in the manner described by 

 KoUiker m Actinophrys Sol, and from ray examinations of the mucous mem- 

 branes of so many classes of animals, I feel persuaded that the mucous lining 

 of the intestines in such animals is truly the homologue of the sarcode in 

 Actinophrys Sol and in the Spongiadae. 



I will not enter at the present time fully into this subject, as I trust I shall 

 hereafter, by further investigations, be enabled to do so more completely and 

 effectively. 



In conclusion I may observe, that I have been thus particular in detailing 

 minutely the history of the actions of the specimen of Hymeniacidon carun- 

 cula that has been the subject of so great a portion of this communication, as 

 it leads us to some very interesting conclusions. We learn by the daily 

 records of its actions, that it is neither the mere stimulus of light or even the 

 presence of fresh water, or the abundance of its natural food, that will at all 

 times stimulate these animals to action, as in vegetables ; but that, on the con- 

 trary, they select or reject their food like other animals as their necessities 

 may dictate ; and not the least curious part of the history of this sponge, is 

 the power it displayed to determine what parts of its organs should be called 

 into activity, and what should be quiescent. 



During the course of these observations I have frequently observed other 

 specimens of the same species, and have tested the degree of their action or 

 repose by the application of a few drops of sea-water charged with molecules 

 of indigo ; and in almost every case where the oscula were in the slightest 

 degree open, I have found that although apparently inert, there usually re- 

 mained a very gentle ex-current action. It will be remembered also, that in 

 the course of the records of the action of the sponge which has formed the 

 principal subject of these observations, the general effect of the removal 

 of the animal from the water is the entire closing of the oscula ; but that on 



