1889-90.] MORPHOLOGY AND PHYSIOLOGY OF THE CELL. 261 



3. Plasmosomata, migrated, or extruded from the nucleus into the 

 cell protoplasm. 



I. Parasites. 



These are, as already said, usually, but'not always, placed between the 

 membrana propria and the nucleus of the cell. They vary in size, measur- 

 ing in their extreme limits I/a and 9/x, and their shape, usually oval, may 

 also be oblong, spherical, elongated, club-like, or crescentic in section. 

 They are not very sharply separated from the protoplasm of the cell and 

 if the latter is dense, their outlines are distinguished with difficulty. 

 Their structure varies also, but there are certain features in this 

 respect which are tolerably constant for the great majority of these 

 forms. These are the central cavity and the fibrillated appearance, 

 the fibrillae, as a rule, appearing as if wound around the central 

 cavity. The central cavity may contain from one to several zymogen- 

 like granules. The fibrillae do not appear as if wound tightly, but are 

 more or less tortuous in their course and the outermost ones may appear 

 ragged, or project loosely into the surrounding protoplasm. This fibril- 

 lated arrangement is best seen in Flemming's Fluid preparations from 

 freshly captured Diemyctyli^ and, especially, in those on which the reagent 

 has been allowed to act for twenty-four hours. The osmic acid and the 

 haematoxylin in such give these bodies a dark brown stain, which deeply 

 contrasts with the lightly or non-stained, surrounding protoplasm. In 

 corrosive sublimate preparations, on the other hand, the fibrillation usually 

 does not appear so distinct except under high powers when it readily be- 

 comes manifest, and hrimatoxylin gives it a faint reddish violet stain. 

 Zymogen granules are entangled in the peripheral fibrillae, often so abun- 

 dantly, that they obscure the presence of the organism in question. 



This stage is the most common, but in order to understand its na- 

 ture, it will be necessary to consider the characters of the other forms 

 found even in the same sections. These present more the appearance 

 of Plasmodia, are usually much smaller, and they take a deeper and more 

 uniform stain with eosin. In the protoplasm of these, one can, at times, 

 see concentric laminated slits, which are apparently an indication of a ten- 

 dency to form fibrillae, but which may also indicate that these plasmodia- 

 like masses are derived by the fusion of the protoplasm of a coiled 

 thread. Such coiled threads are rarely seen in ordinary preparations, 

 but very frequently in sections from the pancreas of some Dientyctyli^ 

 which have fasted for about two months (Fig. 8). These coils have 

 been, now and again, found to be dense in sections from the pancreas 

 removed fifty to sixty hours from the animal after the injection of p lo- 



