HISTOLOGY AND DEVELOPMENT OF MYEIOTHELA PHRYGtA. 527 



the close of a digestive act. The disintegration of the prey is 

 accompanied by a great amount of solution, so that after 

 digestion has been in process for some time the enteric cavity 

 contains a number of fragments of the prey floating in a fluid 

 rich in proteids, which form a deeply-staining granular precipi- 

 tate after treatment with corrosive sublimate. The disin- 

 tegrated fragments of the meal find their way into the foot 

 and blastostyles, the somatic fluid probably being circulated 

 by the active movements of the animal, which include the ex- 

 tension and retraction of the blastostyles, and possibly by the 

 cilia, which appear to be borne here and there by the endo- 

 derm-cells. The process of digestion is therefore largely 

 extra-cellular ; but this is not all, intra-cellular digestion takes 

 place to a marked, but undoubtedly a subordinate extent, and 

 is mainly, perhaps entirely, confined to the amoeboid and 

 mobile apical cells of the villi in the tentacular region. 



If these cells be examined in an animal killed towards the 

 close of digestion they will often be found to contain the more 

 or less imperfect capsules of thread-cells or irregular frag- 

 ments of hyaline material, which recall the cuticle of a Crusta- 

 cean, and probably are fragments of that structure. 



In fig. 17 such a nematocyst is shown embedded in a turbid 

 mass of darkly-staining material, which occupies a vacuole 

 in the cell protoplasm. At n is another nematocyst, now no 

 longer lying in a vacuole, but embedded in the cell proto- 

 plasm. The digestion of the food-mass with which this nema- 

 tocyst was associated having been completed, the vacuole has 

 filled up. 



Other interesting points may be mentioned which point to 

 this intra-cellular digestion. In some cases an enclosed mass 

 may be found embedding a more or less perfect nucleus. By 

 a careful examination of different cells we may see such nuclei 

 in various stages of disintegration, until they are finally resolved 

 into chromatin granules which are scattered through a pseudo- 

 podial-like lobe of protoplasm, which appears to be thrust into 

 a vacuole as the digestion of its contents becomes complete. 



Carmine grains injected into the enteric cavity are eagerly 



