OF MICR O- OR GANISMS. 95 



general the results of Gruber as to the function of the 

 nucleus in the vital phenomena of ciliated Infusoria, 

 he has endeavored to fix with more exactness a cer- 

 tain number of important points. His first experi- 

 ments, like those of Gruber, were conducted upon the 

 Stentor cceruleus, a species of which the size renders it 

 better adapted to this sort of experimenting. In an 

 observation which we shall take as a type, and which 

 is represented by the figure sent to us by M. Balbiani, 

 the body of the Stentor is cut by two transverse sec- 

 tions; three divisions are obtained, each of which con- 

 tains a fragment of the nucleus. We will remember 

 that the nucleus of the Stentor is like a long string of 

 beads; it is not at-all rare to see a fragment of a Sten- 

 tor contain one or more beads. 



Fig, 12. Artificial division of the Stentor cceruleus. 

 (After Balbiani.) 



Let us follow the phenomena presented in the 

 middle segment. This segment contains only a single 

 grain of the nuclear chaplet; directly after severance, 

 it assumed a globular shape; the day following, it had 

 lengthened, had grown a tail at the posterior extrem- 

 ity, and upon the anterior part there had appeared, 

 distinctly outlined, a crown of cilia longer than those 

 upon the body; in other words, a peristome had 



