OF MICR O- OR GANISMS. 93 



movements, and passes through complicated stages 

 which have been given the name of caryokinesis.* 



But these complex phenomena simply show the 

 function of the nucleus as an histological element; 

 they do not afford any disclosures as to the physiolog- 

 ical role of the nucleus in the cellule. 



Other observations have enabled naturalists to sur- 

 mise what phenomena are subject to the action of the 

 nucleus. In 1881, Balbiani called attention to indi- 

 viduals, belonging to the species Param&cium aurelia, 

 that were destitute of a nucleus and which neverthe- 

 less possessed the power of locomotion the same as 

 ordinary individuals; whence, he concluded that the 

 nuclei exerted no influence upon the phenomena of 

 individual life. Shortly afterwards, Gruber observed 

 small specimens of the Actinophrys sol which absorbed 

 nutriment, changed their position in the liquid, and 

 even fused with each other (zygosis), but which were 

 nevertheless destitute of a nucleus. f 



The idea then occurred to Gruber, and to Nuss- 

 baum likewise, to divide the Micro-organisms by ar- 

 tificial means into several fragments, of which some 

 would contain a nucleus and others not, and then to 

 watch what would come of it. Gruber, to whose ex- 

 periments the most importance attaches, chose as his 

 subject of trial the Stentor cceruleus, a ciliated Infu- 

 sory of great size, which exhibits a nucleus resembling 

 a chaplet of beads (moniliform). He afterwards con- 

 tinued his experiments upon other species, and his 

 conclusion was, that the power to regenerate lost parts 

 belonged to all Protozoans, but that this phenomenon 

 only took place when the isolated fragment contained 



* Kapvov, the nut, and nivrjci^, motion, disturbance. 



t Contributions to the Biologisches Centralblatt, 1885. p. 73. 



