276 Mr. E, W. H. Holds worth on Digestive Power in the Actinise. 



being about twenty hours. Whilst in this condition, some spe- 

 cies become sufficiently transparent to enable us to discern a 

 great part of their internal structure ; and a vertical view of the 

 polype shows the stomach suspended like a single flat membrane 

 from the oral disk. On looking through the sides of the animal, 

 the food may be observed at the bottom of the great cavity — 

 usually in the centre, sometimes a little on one side — and rest- 

 ing on the edges of the converging septa. In this position it 

 stays until whatever pai^t of it is not required by the polype is 

 finally returned through the mouth. I shall presently refer to 

 the condition of the rejected portion ; but I may now inquire 

 in which part of the animal, during the above process, does the 

 mechanical operation take place that Mr. Lewes states is the 

 only one by which the food is prepared for assimilation ? It 

 cannot be in the cavity of the body, for that is fully and rigidly 

 distended with water whilst the food is within it ; so that no 

 pressure from mutual contact of the membranous septa can be 

 exerted to extract the juices of the meat. The only time when 

 such an agency can be employed is during the first passage of 

 the food through the stomach, or subsequently on its return. 

 In either case, the operation would only last for a very few mi- 

 nutes ; and undoubtedly some pressure may be exercised during 

 the process of regurgitation, as the rejected food must find its 

 way upwards from the large gastric cavity into the free open 

 extremity of the membranous stomach — a proceeding very much 

 like that of getting out of a flexible lobster-pot : the contortions 

 the polype sometimes makes whilst this is going on show the 

 difficulty it labours under; however, it is soon over, and the 

 morsel is ejected, — but in what condition ? Is it in a state that 

 can be accounted for by mechanical action only ? 



It may be here mentioned that I have various species of Ac- 

 tinice that have been in my possession for periods ranging from 

 six months to as many years; and as they are generally fed 

 once a week, and for the most part on partially cooked beef, 

 frequent opportunities are afibrded me for observing the results 

 of feeding these animals on substantial food. 



I find, then, that the remains of the meat are returned in one 

 of three conditions, viz. : 



1 . Unaltered in shape, the muscular fibre intact, but with the 

 appearance of having undergone simple maceration in sea-water, 

 and enlarged rather than contracted in size. 



2. In a rounded mass, reduced in size, not only from being 

 rolled into a ball, but also in consequence of a partial solution 

 of its substance ; the muscular striae faintly visible. 



3. In the form of minute particles, whose aggregate bulk 

 frequently does not equal one-fiftieth part of the original piece. 



