OF MICR O- OR GANISMS. 



21 



terior extremity. The edge of its peristome is covered 

 by a belt of vibratile cilia disposed about a spiral 

 line. The mouth occupies the most sunken part of 

 the peristome. 



The body of the animal is striated with longitudi- 

 nal bands; at the plane of the peristome, these bands 

 take a different direction: they become transversal and 

 spiral. In the interior of the protoplasm can be ob- 

 served a contractile vacuole and a nucleus like a string 

 of beads, made up of a large number of grains. This 

 Infusory, like all the Ciliates, mul- 

 tiplies by fission; a contraction is 

 seen to take place in the middle of 

 the body; the segment below the 

 contraction generates a peristome 

 similar to that of the upper seg- 

 ment; then a second contractile vac- 

 uole is formed, and soon the two 

 segments represent two complete 

 animals which possess all their or- 

 gans. Nevertheless,* the two Sten- 

 tors continue to be united for a cer- 

 tain length of time by a bridge of 

 matter, located even with the point 

 where the contraction took place; 

 this bridge of matter gradually 

 grows thinner and thinner and be- 

 comes as fine as a thread. (See 

 fig. 5.) Now, Gruber has observed 

 that the two Stentors united by this F '- 

 bridge of protoplasm exhibit perfect 

 harmony in their movements; they always sway in the 

 same direction at the same time; and this harmony is 

 necessary, because the least contrariety of motion 



Stentor in pro- 

 cess of division. 



