92 ANATOMY AND PHYSIOLOGY 



of Actinia, or of the common Starfishes, we find this 

 substance presenting the same unmistakable and peculiar 

 characters, the pellucid, semi-transparent gelatinoid appear- 

 ance, abounding in molecnles and minute vesicles always 

 more or less in a state of collapse. The mucous membranes 

 of the intestines of a mouse which was drowned in warm 

 water to preserve the tissues during examination as nearly 

 as possible in a natural condition, when examined by 

 transmitted light with a microscopical power of 666 linear, 

 presented the same characteristic appearances. Some por- 

 tions of the mucous lining of the intestine abounded more 

 in the particles than others ; they also varied considerably 

 in size, and were all more or less in a state of collapse, and 

 none had the appearance of living and fully distended 

 vesicles. These molecules were not confined to the surface 

 of the mucous or sarcodous matter, but were also embedded 

 at various depths in its substance. They varied consider- 

 ably in size and character within a small distance. At 

 one place I observed a group of them, each being of, com- 

 paratively, a considerable size, while, at a very little 

 distance, there was but very rarely a large particle to be 

 observed, and when they appeared to be of more than 

 average number and size, they were observed to be at the 

 surface of the mucous or sarcodous structure, as if they 

 had not yet been absorbed and lessened in size by the pro- 

 cess of digestion. All these circumstances are indicative of 

 the molecules being extraneous to the sarcodous structure 

 itself, and tend to induce us to believe them to be the 

 nutritive matters in course of preparation for final assimila- 

 tion with the blood after the previous preparatory portions 

 of the process of digestion in the stomach. 



These are the general characteristics of the sarcodous 

 system throughout the whole range of the animal kingdom, 

 and, as may naturally be expected, may be traced in the 

 Spongiadse, however they may differ in their structure and 

 organization. Every cavity in the interior of the animal is 

 coated with a thin stratum of sarcode, over which the incur- 

 rent and excurrent streams of water, continually passing 

 through the sponge with a greater or less degree of activity, 



