1889-90.] MORPHOLOGY AND PHYSIOLOGY OF THE CELL. 267 



Nothing can probably demonstrate more effectually the non-secretory 

 nature of these elements than the fact that they are present in the cubical 

 cells lining the ducts and ductlets of the gland (Figs. 1 1 b, chin and 12 rchc). 

 Nor are these bodies confined to the pancreas, for I have found them in 

 the ephithelial cells of the intestine, in the liver, the kidney and cutaneous 

 epithelium of Diemyctylus and Nectunis. ^ They indicate, however, how 

 little of a tissue is normally lost to itself and how it husbands its waste 

 material. It is, of course, on first view, surprising that the pancreatic cells 

 should exhibit amoeboid properties, but it is less so when we remember 

 that the hepatic cells, which in sections have a definite and apparently 

 fixed form, manifest in the teased out scrapings from the cut surface of 

 the fresh liver amceboid movements. 



3. Migrated or Extruded Plasmosomata. 



Platner denies that the nuclear plasmosomata migrate, and, at first, I 

 was inclined to this view. It is easy to see in well hardened sections of 

 the pancreas plasmosomata driven by the knife from the periphery of the 

 nucleus into the cell, the nuclear membrane torn, and the cavity pre- 

 viously occupied by the plasmosoma empty. This occurs chiefly when 

 the plasmosomata are large and placed next to the nuclear membrane. 

 The apparent protrusion of the nuclear membrane, in some cases, is really 

 due to a shrinking of the same at every part, except opposite the plas- 

 mosoma, which offers a resistance. I found, however, as the investigation 

 proceeded that there were phenomena which could not be so explained. 

 For example, in the pancreas of a young Aniblystoma^ about one-fourth 

 of the nuclei showed plasmosomata which were fixed in the act of passing 

 from the nucleus to the cell. I saw plasmosomata of dumb-bell form half 

 outside and half within the nucleus and some were embedded in the cell 

 protoplasm. I saw this condition, moreover, but less marked, in the pan- 

 creas of a specimen of Diemyctylus removed twenty hours after the injection 

 of pilocarpin. Though the evidence was unmistakeable, I cannot but think 

 that if the phenomena are constant or normal, they should be observed 

 oftener. In any case the migration or extrusion has, from all that I see, 

 no connection with the processes of secretion. If it is a case of extrusion, 

 one might imagine it to occur readily in the pancreas of any specimen of 

 Diemyctylus, unless one were to suppose that in certain stages of cell ac- 

 tivity the nucleus is more contractile. My attempts to establish the 

 correctness of such a supposition resulted unsuccessfully. 



That the extrusion or migration is not a normal phenomenon appears 

 to be borne out in the history of the extranuclear plasmosomata. They 

 either disintegrate and form granules like that of zymogen in size and 



