512 GENERAL PHYSIOLOGY 



a nucleus. During the frequently long time that elapses between 

 the removal of the nucleus and the death of the enucleated proto- 

 plasmic mass, certain metabolic phenomena gradually disappear, 

 while many activities continue even until the last moment before 

 death. The disappearance of phenomena shows at once that by the 

 removal of the nucleus the metabolism of the protoplasm has under- 

 gone a disturbance. 



One group of phenomena that disappear relates to the treatment 

 of ingested food, and may be especially well observed in the naked 

 protoplasm of Rhizopoda. If in a Polystomella, whose delicate, 

 snail-like, calcareous shell is filled with a protoplasmic body that 

 is usually uninucleated, a piece of the shell containing non- 

 nucleated protoplasm be skilfully cut off, after some time the 

 protoplasm forms again wholly normal pseudopodia, and for some 

 days behaves like an uninjured Polystomella. Small Infusoria, which 

 serve the organism as food, are still caught by the pseudopodia, 

 which latter are covered with a delicate viscous secretion ; and 

 under certain circumstances these Infusoria can even be killed by 

 the action of the pseudopodial protoplasm surrounding them ; but 

 no digestion takes place. 1 The same observation can be made 

 readily upon large Radiolaria, like Thala&sicolla, which can with 

 ease be deprived of its central capsule containing the nucleus. 

 After this operation the large non-nucleated protoplasmic body 

 behaves like a complete Thalassicolla. The pseudopodia hold fast 

 the swimming food-Infu&oria and surround them with their proto- 

 plasm. The Infusoria are killed and sometimes even altered in 

 form, but complete digestion never takes place. 2 Hofer ('89-'90) 

 observed the same thing in large specimens of Amceba. When he 

 divided under the microscope Amcebce that had devoured Infusoria, 

 so that the latter were present in the nucleated as well as in the 

 non-nucleated half of the protoplasm, those in the latter half 

 underwent feeble digestion at first and then ceased to be affected, 

 while those in the nucleated half were completely digested, as in 

 an uninjured Amceba. It follows from all these experiments that 

 the assimilation of ingested food ceases in the protoplasm after the 

 extrusion of the nucleus. 



As with the consumption, so the production of certain substances 

 by the protoplasm ceases after removal of the nucleus. A non- 

 nucleated protoplasmic mass of Polystomella no longer excretes 

 calcium carbonate to complete its calcareous shell, while nucleated 

 pieces repair an imperfection in the shell immediately by laying 

 down new calcareous masses at the wounded place. 3 The secretion 

 of slime by the naked protoplasm of Amceba, as Hofer ('89-'90) has 

 shown, is not observed in non-nucleated masses ; hence after 

 enucleation such pieces float in the water, while nucleated pieces, 

 like uninjured Amcebce, immediately attach themselves again to 

 1 Cf. Verworn ('88). 2 Cf. Verworn ('91). 3 Cf. Verworn ('88). 





