Quantitative Reduction of the Tissues 



79 



is an additional factor which the writer has not found recorded 

 hitherto. 



As the stomach and intestine undergo reduction in length, 

 their walls become thicker. As pointed out by Ratner 2 , the in- 

 crease in the thickness of the several layers in the walls of these 

 organs is brought about not by active cell proliferation but by 

 rearrangement and aggregation of the elements already present. 

 During the early phases of this process many of the smaller 

 blood vessels become obliterated or constricted; consequently 

 autolysis of many of the tissue elements is initiated. The tis- 

 sues become infiltrated with leucocytes and phagocytosis, doubt- 

 less, plays a part in the removal of tissue fragments. 



During the progress of metamorphosis, the stomach and in- 

 testine become free from ingested material and masses of cel- 

 lular debris, including nuclei in which a portion of the chroma- 

 tin still reacts to the basic stain, occur in the lumen throughout 

 the stomach and small intestine. The gastric and intestinal 

 epithelium becomes increasingly irregular as metamorphic 

 changes advance. The nuclei of all the epithelial cells no longer 

 remain at approximately the same level, but many of them ap- 

 proach the free surface of the epithelium. Not infrequently the 

 nuclei of epithelial cells protrude and the cells slough into the 

 lumen. Both in the stomach and intestine, cells from the mucosa, 

 including many of the invading leucocytes, also slough into the 

 lumen. In some instances definite points may be observed at 

 which the epithelial cells have separated to permit the extrusion 

 of aggregates of cells from the deeper layers of the mucosa and 

 the submucosa; in others, only sufficient separation of epithelial 

 cells occurs to permit the displacement of individual cells from 

 the deeper layers into the lumen. The frequency with which 

 the extrusion of cells either singly or in aggregates from and 

 through the epithelium occurs and the volume of the cellular 

 debris present in the lumen of the stomach and intestine suggest 

 that a large part of the quantitative reduction of the tissues in 

 these organs is brought about by this process. 



- Ratner, T., Metamorphose des Darmes bei der Froschlarve, Dorpat, 1891. 



