Collected scientific papers of Sir William Bate Hardy.

  • William Bate Hardy
Date:
1936
Catalogue details

Licence: In copyright

Credit: Collected scientific papers of Sir William Bate Hardy. Source: Wellcome Collection.

    33/978 (page 15)
    almost exclusively composed of vacuolate cells. A few gland cells lie scattered in the proximal third of each blastostyle. Taking the most general view of the structure of the epithelium lining the enteric space of Myriothela as described in the preceding pages, we see that it may be divided into different regions. These are (1) An oral region characterised by the presence of sense cells and cilia in its upper part, and of numerous glandular cells, the goblet cells, in its lower part. (2) A middle zone comprising the middle region of the entire animal, and characterised by the presence of numerous gland cells. (3) The blastostyles and the foot region, where the endoderm is almost exclusively composed of vacuolate cells, usually loaded to the full with stored nutritive material in the form of nutritive spheres. Of the function of the goblet cells I can say little. From their position I had supposed that their stored material was discharged when the food was first received, and that they were concerned in the elaboration of a digestive ferment or ferments. But I have found them apparently unaltered in animals which have just taken in their prey (a crustacean). The glairy, sticky appearance of the contents of the expanded portion of the goblet, however, suggests the idea that they form a strongly adhesive surface to what may be called the prehensile portion of the endoderm. The gland cells, on the other hand, present no especial difficulties. Fig. 18 a represents one shrunken and discharged as seen in an animal at the close of a digestive act, that is with merely the detritus of a meal in its enteric cavity. Fig. 18 shows one taken from a fasting animal. It is fully loaded with granules. Fig. 18 6 represents an intermediate condition. The granules are large and coarse, and appear to be formed in the deeper portions of the cell. Their discharge is characteristic, and may be witnessed in preparations from an animal which has just ingested its prey. The granules are extruded, apparently un¬ changed, into the somatic fluid, there to be dissolved. That is to say, they do not break down to form the digestive enzymes until they are free from the cell in which they were formed (fig. 21). The process of digestion. For a long time I was unable to determine the natural food of Myriothela, while at the same time all endeavours to induce it to ingest pieces of raw meat or fragments of Molluscs and Crustacea conpffetely failed. I therefore, in the meantime, turned my attention to carmine and sodium sulphindigotate, and with a fine pipette, inserted through the mouth, injected a drop of sea water containing the one in suspension or the other in solution. Later, however, I wTas more fortunate, and succeeded in obtaining specimens with food in the enteric cavity. In one case the prey was a Crustacean of some considerable size, so that it produced a very obvious bulging of the animal. I did not witness the capture and ingestion of the prey, but the specimen was killed before the