480 Dr. A. Gruber on the 



I have hitherto spoken exclusively of the regenerative 

 faculty of Stentor cceruleus, and now comes the question as to 

 how far this occurs also in other Infusoria. I have already 

 mentioned Nussbaum's experiments, which prove that 0x2/- 

 tricha behaves in the same way ; I have myself operated with 

 Stentor polymorplius and with Climacostomum virens, in both 

 of which the parts removed were replaced within twenty-four 

 hours ; in Paramcecium I also succeeded in removing the 

 anterior end, isolating the posterior end, and finding it regene- 

 rating on the next day. On the other hand, there are other 

 Infusoria which present difficulties that are frequently insur- 

 mountable. Thus Nussbaum could not keep artificially- 

 divided Opalince alive, as no cicatrization of the wounded 

 surface took place ; ciliary action continued for an hour or 

 two, but then the divided portions perished. With Loxodes 

 rostrum experiments in artificial division were equally unsuc- 

 cessful ; these Infusoria usually deliquesce immediately after 

 the section has been made, or if one succeeds in obtaining and 

 isolating divided portions, these perish before any regenera- 

 tion has taken place. 



It is remarkable that OiJalina and Loxodes in particular 

 show themselves to be so little capable of regeneration, as 

 they are both multinucleate, and, as I remarked at the 

 beginning, experiments in artificial multiplication were first 

 made successfully upon multinucleate Protozoa — Myxastrum'^ ^ 

 Protomyxa^ and Actinos'phcerium. 



I have also employed the great Holotrichous Infusorian 

 Cyrtostomum leucos in experiments, and observed that in this 

 also the regeneration does not take place so rapidly as in the 

 above-mentioned Heterotricha, Stentor and Climacostomum ; 

 although a new mouth and oesophagus are formed, the body 

 remains deformed for a long time. Even the Heterotricha do 

 not all behave alike in this point, for I never succeeded in 

 multiplying Spirostomum^ for example, artificially, as it is very 

 difficult to keep isolated in small quantities of water, and even 

 when uninjured soon perishes. Very prohably these differ- 

 ences in the regenerative capacity of the Infusoria depend only 

 on the greater or less faculty of existing under not quite natural 

 conditions, and the power of replacing lost 2)cirts is, in my 

 opinion, propter to all Protozoa, notwithstanding the above-cited 

 negative results. 



But if we inquire why the Infusoria have so high a regene- 



* Myxastrum was referred to tlie Monera by Hackel, as possessing no 

 nucleus ; but very probably the nuclei merely escaped bis notice, for by 

 tbe employment of our present methods of treatment they may easily be 

 shown in Myxastrum liguricum (see Gruber, " Die Protozoen des Hafens 

 vou Genua," in Nova Acta Acad. Leop. Carol. Bd. xlvi. 4, p. 605). 



