The Intracellular Digestion of Thymus Nucleoprotein in Triclad Flatworms

Studies on Feeding, Digestion, and Food Storage in Free-Living Flatworms (Platyhelminthes: Turbellaria)

“…In Polycclis the food is very finely divided by the pharynx and the particles taken in by phagocytosis for intracellular digestion. No evidence of intraluminar digestion was found in this species, either of mixed food or of the three food elements fed separately, in agreement with Willier, Hyman and Rifenburgh (1925) and Kelley (1931) ; the contrary opinion of Arnold (1910) was based on the erroneous supposition that the "sphere cells" of the gut were glandular and discharged into the lumen. Some evidence of intracellular digestion in mesenchyme cells was observed, of food apparently received indirectly from the endoderm cells.…”

“…The natural food was used, whenever possible, to determine the site and course of digestion, but in forms with a phagocytic gastrodermis (especially the triclad) both this and the soft foods used by previous investigators (Arnold, 1909;Willier, Hyman and Rifenburgh, 1925;Kelley, 1931) disintegrated during ingestion and it could not be ascertained whether any intraluminar break-up preceded the phagocytosis and intracellular digestion, nor whether the separate constituents of the food (proteins, carbohydrates and fats) were dealt with differentially. Hence the flatworms were fed either on food which reached the gut in a visibly recognizable condition, or on homogeneous food substances whose digestion could be detected by simple chemical tests.…”

Observations on the Nutrition of the Land Planarian Orthodemus Terrestris (O. F. Müller)

“…reveals only very small amounts of glycogen which occur as tiny irregular granules scattered through the mesenchyme and columnar gut cells. 1925;Kelley, 1931;Jennings, 1957). The typical triclad feeding mechanism, with the pharynx functioning as a suctorial tube which penetrates the prey to withdraw the body contents piecemeal, has apparently proved adequate to the needs of a terrestrial life and is retained unmodified.…”

“…The Turbellaria as a class are carnivorous and previous investigations have shown that the range of prey available to these relatively simple animals has been greatly increased through the development of efficient feeding mechanisms in the form of progressive elaborations in the structure and use of the pharynx (Jennings, 1957). The Tricladida in particular, with the protrusible cylindrical type of plicate pharynx, are active and successful predators and the nutrition of the aquatic forms has already received much attention (Willier, Hyman and Rifenburgh, 1925;Kelley, 1931;Jennings, 1957). Little is known, however, of feeding and digestion in those triclads of terrestrial habit and hence a representative of this group, Orthodemus tcrrestris (O. F. Muller), has been examined to gain some measure of the influence of a land existence upon the typical pattern of triclad nutrition.…”

Intracellular Digestion and Hydrolytic Enzymes in the Phagocytes of Planarians

“…A number of investigators have observed the disintegration of ingested food particles within these cells (Arnold, 1909;Saint-Hilaire, 1910;Jacek, 1917;von Levitzow, 1943), but the methods they employed did not permit elucidation of the mechanisms involved except in a most general way. Kelley (1931), studying the intracelular digestion of nucleoprotein in D. dorotocephala by means of the Feulgen reaction with and without acid hydrolysis, showed that the ingested material was hydrolyzed within the first two hours.To our knowledge, no previous study has characterized the hydrolytic enzymes in the phagocytes of planarians. The present report considers the relationship of three such enzymes to current concepts of intracellular digestion.…”