105 



loosing itself in its upper part into the capillary 

 point, which is often very long, and has very thin 

 articulations. When a filament has left by creeping 

 the mother's body (as in fig. 72), this content (b.) 

 forms a point, often similar to a drop, which grows 

 gradually longer, till it acquires the form of an arti- 

 culated filament; and in this manner the process 

 already described is successively performed. 



Other Os cillatoriae (such as the Oscillatorta ele- 

 gans Ag. fig. 73 74) creep in turning and bending 

 the pointed extremity of their head (a.), from up- 

 wards downwards, or from right to left, as the 

 movement requires. 



If, during this movement, filaments or other exi- 

 guous bodies present themselves on its way, the 

 animalcule feels them with the point of the head, till 

 it has gone round or over them. Does it meet larger 

 bodies, it adheres to them or ascends over them, but 

 it very soon puts aside the smaller ones, or, as the 

 Naviculae do, drives them along with itself. 



The Frustuliae move in less than a minute, upon 

 a surface of one line. The Oscillatoriae, in four and 

 twenty hours, move from one to four inches. 



Our Diatomeae, found in rivers, are almost motion- 

 less; those which inhabit the sea move quicker. 

 Many animalcules of this class move only during the 

 night. I have seen the Closterium costatum (fig. 61.) 

 and the Closterium didymotocum (fig. 64.) ascend, 

 during that time, from the bottom of a glass cylinder, 

 from 4 30 lines, upon the inside of the glass, whilst, 



