164 Dr. M. Verworn's Biological Studies of Protista. 



experiments on Infusoria. Nussbaum found that in Oocytricha 

 only the nucleiferous fragments became regenerated into new 

 individuals, and Gruber was able by his beautiful experi- 

 ments to establish the same thing with regard to Stentor 

 ccerulens. I may mention here that I have myself repeated 

 Gruber's experiments on Stentor cceruleus with the same 

 results, and have also made the same experiments on Lacry- 

 maria olor. Lacrymaria^ of which I had great numbers of 

 individuals at my disposal, was so far a favourable object for 

 these experiments, as it was comparatively easy to detach 

 portions without any fragments of nucleus, which I found to 

 be more difficult with my Stentors. However, in Lacry- 

 maria 1 have also obtained the same results, and therefore it 

 seems to me indubitable that regenerations take ■place under 

 the influence of the nucleus and cannot he effected without it. 



In Polystomella 1 made a further observation upon the 

 non-nucleate pieces which perhaps will be of interest, I made 

 trial whether the non-nucleate portions take in nourishment 

 by placing in the water containing them numerous small 

 marine Protista which might serve them as food. In clear 

 weather the fragments had extended very abundant pseudo- 

 podia, and among these the Protista moved about. I now 

 repeatedly observed that swimming Flagellata remained 

 adherent to the pseudopodia, then made movements to escape, 

 and, when they did not succeed in tearing themselves free, 

 were slowly drawn to the shell with the pseudopodia. With 

 one fragment there were with the Flagellata many specimens 

 of Eu^lotes cliaron in the same drop of water ; but these 

 appeared to be too large to be attacked. When they came 

 near the pseudopodia they alwajs made a quick backward 

 movement which placed them out of danger again. Once, 

 however, I observed that a Euplotes which chose to run over 

 a whole bundle of pseudopodia remained attached to several 

 pseudopodia at once, and in spite of its endeavours to escape 

 was slowly drawn towards the shell. During this process its 

 movements became gradually weaker and weaker ; soon there 

 were only from time to time a few jerking movements of the 

 posterior cilia, and finally, in about twenty-five minutes, all 

 motion ceased. Some time afterwards, when the fragment 

 changed its place, the Infusorian remained behind, and, as I 

 ascertained, was really dead. I made the same observation 

 another time upon a metabolic Euglena. 



That inception of nourishment should occur in non-nucleate 

 fragments does not strike me as remarkable, as I have recog- 

 nized it to be a pure reflex action which only takes place upon 

 mechanical irritation (movement of the food-organisms &c.). 

 I could imitate it by means of artificially moved foreign 



